Fresh airCooled airHeated airVentilated airRecycled airWaste air

BOVA Futurair

Janu

ary 2

000

- GB

2322

57

Futurair 1

Index

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Assembly drawing of heating, ventilation and airco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Roof unit assembly drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Operation of BOVA FUTURAIR system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Explanation to control unit push-buttons and selectors . . . . . . . . . . . . . . . . . . . . . 5System description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Automatic control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Emergency on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

General remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Trouble-shooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Control unit error codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Explanation to error codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11WABCO diagnostic controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Maintenance and repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14R134a gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Operational mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15PWM motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Water valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Roof unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Water baffle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Dust filter or cara filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Relays and fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Order numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Annex 1: Complete circuit diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Annex 2: Operational form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Annex 3: Operational graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Annex 4: Temperature sensor resistances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Version 3, from chassisnumber 6003370 Oktober 1997

Futurair 2

Introduction

The BOVA is equipped with the BOVA Futurair system, which is a fully automatical heating,ventilation and airco(nditioning) system for the passenger seat room. The heating and ventilation ofthe driver's seat is regulated manually using the front heater. If the airco is integrated, grids in thefront ceiling section blow cool air on to the driver's seat.

In coaches not equipped with the airco the operation of the system as a whole remains identical.Any differences between ventilation model and airco model will be pointed out.

Futurair 3

Assembly drawing of heating, ventilation and airco

1 front heater2 fan3 (manual) water cock4 underfloor heater 15 underfloor heater 26 underfloor heater 37 underfloor heater 48 front water valve 9 rear water valve10 roof heater water valve11 preheater12 preheater water pump13 stop cocks (3)14 roof units (2)

15 condenser16 drier17 liquid vessel sight glass18 condenser fans (4)19 magnetic coupling20 high-pressure pressostat21 low-pressure pressostat22 compressor (with sight glass to rear)23 spare dynamo (not for Mercedes)25 PWM-driven fans (4) for underfloor heaters

Futurair 4

Roof unit assembly drawing

24 PWM (Pulse Wide Modulation)-driven fans (6) for roof unit26 heating and evaporation units (2)27 air valves (2)28 defrosting thermostat (to the left)29 expansion valves (2)30 dust filters (2), with as optional item two cara filter types, with or without carbon coatings

(8, 4 on each side)31 locks (4)32 adjusting motor for left-hand and right-hand air valves34 ventilation nipples (2)35 roof unit water baffles (2)

Futurair 5

Operation of BOVA FUTURAIR system

Control unit

Explanation to control unit push-buttons and selectors

Selection of required coach interior temperature in range from about 18NC to 28NC.This range varies along with the outside air temperature. With the selector in itscentral position, the setpoint may range from about 23NC to 27NC. This setpoint iscalled the comfort value.

Manual raise or reduction (max. 2NC) in AVS-channel temperature set by controlunit.

Manual raise (max. 15%) or reduction (max. 10% ) in flow rate, set by control unit,of exhaust air from the nozzles.

-8

Futurair 6

a) Inquiry after outside air temperature; is displayed for 3 seconds.

b) Depression for over 3 seconds and simultaneous depression of button 5results in appearance of 0 on display. Depression of button 4 (-) enables thetemperature in the coach interior rear to be set lower than that in the coachinterior front. The longer it is pressed, the higher thedifference between rear and front (max. reduction is2NC). Each time the button is pressed, a higherfigure appears, preceded by a - sign, and one moreblock is added on the display. The highest figurepossible and the highest number of blocks is 8. Oncontact disengagement followed by re-engagementthe front and rear temperatures are reset to the same value (0).

a) Inquiry after coach interior temperature; first that in the front (8) isdisplayed and, some two seconds later, that in the rear (9).

b) Depression for over 3 seconds and simultaneous depression of button 4results in appearance of 0 on display. Depression of button 5 (+) enablesthe temperature in the coach interior rear to be set lower than that in thecoach interior front. The longer it is pressed, the higher the differencebetween rear and front (max. rise is 2NC). Each time the button is pressed, ahigher figure appears, and one more block is added on the display. Thehighest figure possible and the highest number of blocks is 8. On contactdisengagement followed by re-engagement the front and rear temperaturesare reset to the same value (0).

Preheater programming. Three different times can be programmed in 24 hours. Thepreheating period is limited to 60 minutes. On depression of button 6 a 1, 2 or 3appears on the left-hand display section. Depression of buttons 4 and 5 enables therequired engagement period to be set. Once set, the required time can be activatedby the user waiting until the display returns to its regular time display mode (thistakes about 20 sec.). If programmed, the LED inside the button remains on, whichmeans that only one time can be activated. On depression of the button theactivated program is displayed. Continued activation of this time requires another20 sec. waiting time. Program deletion is possible on depression of button 6 untilthe LED inside the button goes out.

Setting of digital clock, which normally appears on the display, by continueddepression of button and simultaneous depression of button 4 (-) or 5 (+).

Manual preheater (dis)engagement. Normally, it is the electronic control unit thatautomatically (dis)engages the preheater. Depression of this button results indisengagement of the automatic preheater control unit. Operations remain manualuntil contact disengagement followed by re-engagement.

Airco compressor disengagement. On contact engagement the LED inside thebutton lights up. If required, the compressor can be engaged by the electroniccontrol unit. It is engaged the moment bar 'AC' on the display lights up. Ondepression of this button the LED goes out, and compressor engagement by theelectronic control unit is no longer possible. If the electronic control unit considersthe use of the airco necessary, the bar lights up to show that the use of the airco isrequired for reaching the desired temperature.

Futurair 7

Change-over from inside-to-outside air ratio determined by control unit to 100%inside air, within a fixed period of about 10 minutes. After this period the controlunit resumes valve positioning. This feature is applied in such environments astunnels and car wash lines.Redepression of this button within the same 10 minutes results in a return toautomatical positioning.

Display:a) 1-2-3: programmed preheater reaction time.b) 'HEAT' bar lights up on activation of underfloor heaters.c) 'AC' bar lights up on activation of the airco or whenever the

use of the airco is required for reaching or retaining thetemperature setpoint.

d) Whenever the outside air temperature drops below + 3NC, a red barappears, the outside air temperature is displayed and an acoustic alarmsignal sounds for about 5 seconds (warning against 'slippery road').

e) Display of current time.

Remarks on ventilated coaches:

1) Ventilated coaches are non-airco coaches.2) Under specific conditions it is impossible to reach the temperatures specified in item

1.3) Button 9 (AC) is irrelevant for these coaches.

heating

and

ventilation

0: auto

1: off

2: emergency

Futurair 8

System description

The purpose of the Futurair system is to reach and retain a preset temperature. The AVS channelcontinuously supplies sufficient outside air for ventilation. The system comprises three autonomousunits, which combine to create the required climate:

# heating# ventilation# airco.

The airco is optional. In coaches not equipped with the airco the operation of the system as a wholeremains identical.

There are three operation modes:

# automatic control of heating, ventilation and airco# off# emergency on

These modes are set by activation of the switch on the centralconsole.Each unit will be discussed separately, although, as stated earlier, in practice they never functionindividually but invariably combined with one or two other units.

Automatic control

Heating

For automatical operation of the whole system the switch is set to 0. The desired temperature is setwith selector (1) on the control unit. If this temperature is higher than the current coach interiortemperature, the heating unit is activated automatically, depending on coach interior temperature,outside air temperature and water temperature. The heat is supplied from both the roof heatingunit and the underfloor heaters.The underfloor heaters work on 100% recycled coach interior air, which is taken in through theskirting in the floor. Since the interior temperatures of front and rear are regulated separately, twowater valves are mounted, one for the two front underfloor heaters and one for the two rear ones.These valves are not activated until the water temperature is 50NC or more. They are opened moreor less wide according to the coach interior temperature. If the temperature in the coach interiorfront is too low, the front water valve is opened wider. Consequently more hot water is supplied tothe two front underfloor heaters, which results in a rise in temperature in the coach interior front.The roof heating unit water valve is permanently active, for prevention of a complete circuit shut-off. The roof heating unit works on a mixture of interior and exterior air. The interior air is taken inthrough two grids in the rear central ceiling strip.

An alternative is to adapt the automatically set temperature manually as follows:1 Raise or reduce the temperature of the air from the AVS channels by max. 2NC, using

selector (2). The underfloor heater air temperature remains unchanged.2 Slightly raise or reduce the rotation speed of the roof fans, using selector (3).3 Set temperature in coach interior rear max. 2NC higher or lower than that in the front, using

buttons (4) and (5).

PreheaterWhenever the cooling water temperature is not high enough to heat the coach interior, thepreheater is automatically engaged by the control unit, on the basis of data from the varioussensors and of the temperature setpoint. The moment the motor has heated the cooling water to78NC, the preheater disengages itself. The moment the desired interior temperature has beenreached, it is disengaged by the electronic control unit. An alternative is manual preheaterdisengagement. In this mode operations remain manual until the contact has been disengaged. Attemperatures over 10NC the preheater is no longer engaged by the electronic control unit. Besides,airco unit engagement results in preheater disengagement.

Futurair 9

Ventilation

The ventilation unit works on the same system as the heating unit. With the switch set to (0), thecontrol unit regulates the ventilation fully automatically (in combination with heating unit or aircoor both), according to temperature setpoint, water temperature, coach interior temperature andoutside air temperature. Ventilation is provided by the roof fans, which inject outside air only or anair mixture, according to these temperatures.With the roof unit air valves pointing up, only recycled interior air is being injected. With the valvespointing down, only outside air is being injected into the AVS channels. Since the valves are usuallyin an intermediate position, both interior air and outside air are taken in. Only with the smogbutton pressed, do the air valves point up.

Airco

The airco is accommodated in the roof unit. Whenever the airco is used, the preheater is off.The airco is active only with the switch set to (0), which means in the automatical mode. If required,it is engaged automatically. It can be disengaged with selector (9) on the control unit.The relays activate the magnetic coupling and the condenser fans. These fans remain active.Whenever the roof unit evaporators threaten to freeze, the magnetic coupling is disengaged. Undernormal conditions this must be out of the question because it is impossible to set the exhaust airtemperature in the AVS channel lower than 4NC. The defrosting thermostat is engaged at 1NC anddisengaged at 4.5NC. Another reason for magnetic coupling disengagement is system overpressureor underpressure.

Off

With the switch set to (1) the system is off. The wire for the underfloor heater fan speed signal isconnected to earth, for the fans to stop running. The two underfloor heater water valves are shut.Preheater and water pump are disengaged, with only the front heater remaining operable.

Emergency on

With the switch set to (2), the heating unit changes over to the emergency mode. The only occasionfor its activation is when the temperature in the passenger seat room is no longer under control. The underfloor heater speed signal is disconnected from the system, with the heaters starting torotate at full speed. The underfloor heater water valves are opened. The roof fans can be setrotating by disconnection of the blue plug behind the ashtray. Then the fans start rotating at fullspeed. If the plug is beyond the reach of the ashtray, removethe control element using the hooks delivered with thesystem. The wire colours are violet and white.The roof heater water valve is in the position it was in ondisengagement. If heating through the roof channel is notrequired, the stop valves (D) in the roof unit channel may beshut.If, in an emergency, only the roof fans need to be activated(with floor heating off), pull out the plug behind the ashtrayand set the switch to (1) (off).After system repair, remember to reset the switch to (0)(automatical mode) and plug the system in.

General remarks

The moment the last swing door is closed, the underfloor heater fans are disengaged and the rooffans start rotating at a very low speed. This is to reduce the overpressure inside the coach and tomake the door close more tightly.With the motor off, the speeds of the various fans are low, which results in power saving.

Futurair 10

Trouble-shooting

The control unit accommodates a failure analysis facility for easier trouble-shooting. It checks if thevarious components function properly. If they do not, the display shows an error code (see listbelow). The coach driver can delete this code by pressing buttons + and - simultaneously. Oncontact disengagement followed by re-engagement the error code reappears on the display, butonly if the failure persists. Error codes for failures that have been eliminated are stored in the unitmemory. They can be read from and deleted by the WABCO diagnostic controller (see section onWABCO).

Control unit error codes

0 Test error in control unit parameter memory 1 Interruption or short-circuit between outlet air sensor and control unit 2 Interruption or short-circuit between outside air temperature sensor and control unit 3 Tacho signal 5 Preheater feedback 6 Feedback from engaged water pump 7 Water pump outlet short-circuit

8 Short-circuit between water valve and control unit 9 Contact (+/-) between water valve and control unit10 Short-circuit in right-hand air valve motor11 Contact (+/-) in right-hand air valve motor12 Short-circuit in left-hand air valve motor13 Contact (+/-) in left-hand air valve motor14 Short-circuit at preheater outlet15 Short-circuit at outlet of preheater in ECON mode

16 Short-circuit at anti-freeze unit outlet18 Water pump interruption20 Water valve interruption21 Right-hand air valve drive interruption22 Left-hand air valve drive interruption

24 Left-hand air valve fails to move to required position25 Right-hand air valve fails to move to required position

48 Subelectronic control unit fails to respond49 Test error in subelectronic control unit parameter memory50 Interruption or short-circuit in front interior temperature sensor51 Interruption or short-circuit in rear interior temperature sensor52 No or hardly any contact or short-circuit between magnetic coupling and condenser fans53 Interruption or short-circuit in water temperature sensor55 Subelectronic control unit output stage interruption

56 Interruption or short-circuit in outlet air temperature sensor of front underfloor heater57 No or hardly any contact or short-circuit in water valve of front underfloor heaters60 Interruption or short-circuit in outlet air temperature sensor of rear underfloor heater61 No or hardly any contact or short-circuit in water valve of rear underfloor heaters

Note that the functioning of the components with error codes 18, 20, 21 and 22 is checked only oncontact engagement.

Futurair 11

Warning!

Turn off main switch before unplugging control unit orsubelectronic control unit, in order to avoid damage.

If the control unit does not take any action, first check fuses 37 and 38 for power supply to controlunit and subelectronic control unit. If these fuses are intact, check if the control unit is plugged in.

Explanation to error codes

0... Inspection of control unit interior has revealed error. Control unit is due for replacement.

1... Inspect outlet air sensor in AVS channel. It is accommodated to the right-hand rear andconnected to terminals 28 and 35 of the control unit. See annex 4 for resistances of thissensor.

2... Inspect outside air temperature sensor, which is accommodated behind the right-handheadlamp corner and connected to terminals 28 and 34 of the control unit. See annex 4 forresistances of this sensor.

3... Check if tacho is connected properly. If so, check if disc is mounted tightly and if tachoworks to satisfaction.

5... First check if preheater is working. If so, inspect wire between terminal 13 of control unitand lead 30 of relay 6. Terminal 13 should be energized with 24 V. If the preheater fails,inspect fuse 17 and relay 6.

6... Check if relay 5 is activated on preheater engagement and if the pump is working. If so,check if lead 15 on the control unit plug is being energized (leave plug in when preheater isengaged).

7... Check if lead 26 is connected to earth. If so, inspect lead as far as water pump.

8... Check if lead 24 or 25 or both contact earth. If so, inspect lead as far as roof unit watervalve.

9... Leads 24 and 25 contact somewhere. Check if they do near plug on control unit and nearroof unit water valve.

10.. Check if lead 5 or 6 or both contact earth. If so, inspect lead as far as right-hand air valvemotor.

11.. Leads 5 and 6 contact somewhere. Check if they do near plug on control unit, near right-hand air valve motor and near wiring.

12.. Check if lead 3 or 4 or both contact earth. If so, inspect lead as far as left-hand air valvemotor.

13.. Leads 3 and 4 contact somewhere. Check if they do near plug on control unit, near left-hand air valve motor and near wiring.

14.. Output 20 of control unit short-circuits earth. Check if relay 6 is intact.

15.. Output 21 of control unit short-circuits earth. Inspect wiring from control unit to preheater.

Futurair 12

16.. Output 2 of control unit short-circuits earth. Inspect wiring to buzzer behind centralconsole.

18.. Inspect wiring, from output 26 of control unit to water pump, for contact interruptions.Check if water pump works properly.

20.. Inspect wiring, from outputs 24 and 25 of control unit to roof heater water valve, forcontact interruptions. Check if water valve works properly.

21.. Inspect wiring, from outputs 5 and 6 of control unit to switch box in right-hand roof unit,for contact interruptions.

22.. Inspect wiring, from outputs 3 and 4 of control unit to switch box in left-hand roof unit, forcontact interruptions.

24.. Check if the air valve moves up and down, by pressing the SMOG button first to make it goall the way up, and next to make it return to its original position. If the valve fails to move,inspect the control motor and check if the valve can really move freely. If the valve doesmove up and down, check if the left-hand potentiometer in the roof unit is plugged in.Check if potentiometers are properly earthed.

25.. See 24.

48.. Inspect lead 29 of control unit and 6 of subelectronic control unit. Check if wire is intact,and if leads 1 and 20 of the subelectronic control unit are energized and leads 7, 14 and 19are earthed. If any one of these leads is not or poorly connected, the subelectronic controlunit is either not supplied with power or incorrectly addressed (see section on WABCOdiagnostic controller).

49.. An inspection of the subelectronic control unit interior has revealed a failure. It is due forreplacement.

50.. Inspect leads 13 and 10 of subelectronic control unit and wiring to front interiortemperature sensor. Check if sensor is in working order. See annex 4 for resistances of thissensor.

51.. Inspect leads 24 and 10 of subelectronic control unit and wiring to rear interiortemperature sensor. Check if sensor is in working order. See annex 4 for resistances of thissensor.

52.. Check if condenser fans and magnetic coupling are running. Pay special attention to thefans, for a defective fan keeps rotating, owing to the air pressure, although in the wrongdirection. The best plan is to have an operator engage the airco and, at the same time,check if all the fans start rotating. A defective fan starts rotating later, counter to the otherfans. If one or various fans fail to rotate, check if relays 208, 209, 210 and 211 areenergized and activated. Check if wiring and leads from the relay to terminal 2 of thesubelectronic control unit are intact. If the magnetic coupling is not engaged, inspectwiring, pressure sensors on compressor, defrosting thermostat and leads on relay 207 andon terminal 2 of subelectronic control unit.

53.. Inspect leads 23 and 10 of subelectronic control unit and wiring to water temperaturesensor. Check if sensor is in working order. See annex 4 for resistances of this sensor.

55.. Subelectronic control unit is out of order and is due for replacement.

56.. Inspect leads 25 and 10 of subelectronic control unit and wiring to outlet air temperaturesensor of front underfloor heater. Check if sensor is in working order. See annex 4 forresistances of this sensor.

Futurair 13

57.. Inspect wires and leads between terminals 17 and 5 of subelectronic control unit and watervalve of front underfloor heaters. Check if relays 10 and 11 are set so that subelectroniccontrol unit and water valve are interconnected.

60.. Inspect leads 12 and 10 of subelectronic control unit and wiring to outlet air temperaturesensor of rear underfloor heater. Check if sensor is in working order. See annex 4 forresistances of this sensor.

61.. Inspect wires and leads between terminals 16 and 4 of subelectronic control unit and watervalve of rear underfloor heaters. Check if relays 8 and 9 are set so that subelectronic controlunit and water valve are interconnected.

WABCO diagnostic controller

For thorough trouble-shooting the WABCO diagnostic controller can be used. It is the same cabinetas the one used for testing WABCO ABS/ASR. The test card for the Futurair system is available viaBOVA.

Whenever the diagnostic controller is used the front heater should be on, because, during testing ofthe heating unit, the preheater pump is occasionally engaged with the water valves shut.

For details see enclosed diagnostic controller documentation.

Futurair 14

IMPORTANT NOTE

Maintenance and repair

General

Whenever subjecting a coach to maintenance or repair, check thoroughly if the requiredcomponents, oil, gas and other items are available. If these are not used, the system may get badlydamaged.Fill the airco only with R134a gas combined with an ester oil.When replacing components, leave seals fixed until component connection. Components aredelivered with a slight excess pressure. This means that the escape of air on seal removal should beaudible (but not near the hoses) If it is not, return the component for inspection. For smootherassembly of screwed joints lubrication is permitted, although only with an ester oil.On heating system repair the only coolant to be used for refills is the one prescribed by BOVA.

R134a gas

A system equipped with Airco is filled with R134a gas, which replaces the formerly used R12. On noaccount use these two gases indiscriminately. Inside the system use only components speciallyadapted for R134a gas. The same applies to hoses and seals. Hoses must not be bent because oneof the materials they are made of is a rigid plastic against leakage.Since R134a has a high water-absorbing capacity, it is vital for all components to remain sealed aslong as possible. This is to avoid penetration of humid air, and consequent damage.Since R134a does not mix with mineral oils, the only oil type permitted is an ester oil.

Compressor

The compressor is a BOCK FKX4-467 one, to be used only with R134a and an ester oil. It is deliveredas standard item with 2.5 to 2.7 l of ester oil (ISO 55). The reason for the use of ester oil is thatmineral oil does not mix with R134a. If a mineral oil is used all the same, it will slowly but definitelybe carried along by the gas from the compressor, to accumulate somewhere in the system. In thelong run the compressor will start running dry and the system get clogged. The consequence maybe serious damage. When renewing ester oil, check if the new oil has been stored sealed againstpenetration of water.When installing a new compressor, always check, from the type plate, if it is the right one, adaptedfor R134a gas and ester oil.A new compressor has a run-in period of about 200 hours, during which it will exude a bit of oilfrom the sealing rings. Check the compressor oil level through the sight glass at the compressorrear.

Drier

The drier is accommodated next to the condenser. The air flows bottom up. When mounting a newdrier, mind the flow direction, which is indicated by an arrow. If this arrow is absent, install thedrier long side up. Replace the drier whenever opening the system, or else at least once every year.

Relative Absolute

Absolute zero point-1 0

10

10 11

Atmospheric

Overpressure

Underpressure

pressure (bar) pressure (bar)

pressure

Futurair 15

Operational mode

The control unit is equipped for airco testing, which is called the operational mode. On coachdelivery this test has already been performed by BOVA. Check if the airco works to perfection byverifying the data against the curves in the graph in annex 3. These data are:

# high compressor pressure# low compressor pressure# outside air temperature# outlet air temperature in roof channel.

Pre-test conditions:

# Make sure that the coach has been shaded against the sunlight for quite some time inadvance.# Open all the air nozzles.# Shut doors, windows and roof shutters.# Make sure there is no one in the coach.# Ensure that the outside air temperature is 18NC or more.# Equip the compressor with one gauge to the high-pressure end and one to the low-pressure end.# Read the outside air temperature from the control unit.

Start the coach. Set operational mode by pressing buttons 4, 5 and 9 (-, + and AC) simultaneouslyand turning the switch from 1 (off) to 0 (automatical mode). The outlet air temperature appears onthe display. Keep the buttons pressed until the display starts flashing. Let the motor run at1250 rpm (DAF and MAN) or 1200 rpm (Mercedes), which equals a compressor rate of 1500 rpm.Allow the system to stabilize at this speed (this takes a few minutes). Read high and low pressuresand outlet air temperature (with speed unchanged) and note these values plus the outside airtemperature on the operational form shown in annex 2. Verify the data against the curves on thegraph in annex 3 (Attention! The pressures measured are relative pressures. The pressures in thegraph are absolute pressures).

24V

0V

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PWM motors

PWM (Pulse Wide Modulation) means that the motors are driven at infinitely variable speeds, viapulses. The PWM signal may vary between 0 and 60%, which corresponds with a speed from 0 to100%.

Sensors

For control and regulation the Futurair system uses

# outside air temperature sensor# front interior temperature sensor# rear interior temperature sensor# sensors for outlet air temperature in : - left-hand front underfloor heater

- left-hand rear underfloor heater- right-hand rear of AVS channel

# water temperature sensor# defrosting thermostat# sensors for : - compressor outlet pressure (max)

- compressor inlet pressure (min)# two potentiometers for air valve positions.

Outside air temperature sensor:The outside air temperature sensor is accommodated behind the left-hand head lamp corner. It isvital for interior coach temperature adjustment. Besides, it warns the driver against road surfacefreezing ('slippery road'), although only once. Whenever the temperature drops below 3NC, a signalis produced and the outside air temperature shown on the display. On contact disengagementfollowed by re-engagement the warning against frost reappears. Whenever the sensor fails, adefault value is assumed according to the temperature selector position. With the selector turned toits leftmost position, this value is +30NC, and to its rightmost position it is -10NC. The display showsthe default value with 'NC' flashing.

Interior temperature sensors:The two interior temperature sensors measure and adjust the temperatures in the front and the rearof the coach. Whenever either fails, the temperature measured by the other is taken as defaultvalue. If both should fail, a default value is taken and displayed with the 'NC' flashing.

Outlet air temperature sensors:The three outlet air temperature sensors measure the outlet temperatures of the fans. One isaccommodated to the right-hand rear of the AVS channel, to measure the roof fan temperatures.The two other ones are accommodated in the two left-hand underfloor heaters, to measure thetemperatures of the front and rear heating system circuits. If any of the sensors fails, thetemperature recorded last is taken as default value.

Water temperature sensor:The water temperature sensor is accommodated in the cooling water system right ahead of thepreheater. Whenever it fails, 70NC is taken as default value.

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Defrosting thermostat:The defrosting thermostat is an additional safety unit against system damage. It is accommodatedin the left-hand roof unit, to measure the combiblock temperature. The moment the combiblocktemperature reaches 1N, the thermostat, and consequently the magnetic coupling, are disengaged.At 4.5NC the thermostat is re-engaged. Under normal conditions this situation must be excluded,for the roof fan exhaust temperature is kept higher than 4NC.

Pressure sensors:The pressure sensors on the compressor measure the pressures to the compression (outlet) end andthe suction (inlet) end, to protect the system. The moment the outlet end pressure exceeds 22 bar(absolute value), the magnetic coupling is disengaged. This situation may occur when the system isclogged up. The moment the inlet end pressure drops below 1.35 bar (absolute value), themagnetic coupling is disengaged. This situation may occur in the event of system leakages.

Potentiometers:The potentiometers are integrated in the valve motors, to check if the required air valve positionsagree with the setpoints.

Water valves

The Futurair system uses three water valves, two for the underfloor heaters and one for the roofheater. They consist of a DC-motor, actuated by the electronic control unit, and a valve.

Emergency control:If any DC-motor breaks down, the valve can be opened or shut with a screwdriver, but only afterdetachment of the motor from the valve.

Roof unit

The roof unit accommodates components for airco, heating and ventilation. It is accessible via theroof. The two service traps are opened via two fasteners. The valves bear rods to keep them open.When shutting them, make sure that the water baffles fit in their proper places. The best plan is topull them out and shut the valve. After shutting check if the water baffle covers the coach roof allover its length.The roof units also accommodate the heating system vent nipples.

Water baffle

The water baffle holds back the water from the roof and serves as coarse prefilter. Check it atleast once a month and clean it, if required. Remove it by unscrewing the four nuts.

Dust filter or cara filter

This filter is accommodated in the roof unit. Check it at least once a month, and clean it, ifrequired. Remove it by unscrewing the two screws in the roof unit.

Relays and fuses

Annex 1 presents a complete circuit diagram for heating, ventilation and airco. See wiring diagramon page 6 for positions of fuses, relays and plugs.

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Order numbers

Electric components

Control unit for system with airco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219592Control unit for system without airco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219593Subelectronic control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219594Buzzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B190179Water valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219107Preheater Webasto . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B207444Preheater water pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B500091PWM motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B511488Air valve motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L: B511498, R: B511499Defrosting thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B511502Magnetic coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219595High-pressure thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B511045Low-pressure thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B511044Water temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B221475Outlet air temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219526Interior temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219526Outside air temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219511

Heating

Front heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B193759Underfloor heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219512Roof unit combiblock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L: B511494, R: B511495Heating block (if airco is absent) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L: B511496, R: B511497Webasto . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B207444Preheater pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B500091

Airco

Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219520Roof unit combiblock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L: B511494, R: B511495Expansion valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B511491Condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219510Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219518Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B219523

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Annex 1: Complete circuit diagram

The plugs are numberd by a character and a number. The character indicates the lokation of theplug in the coach. These lokations are:

A: Located behind the middle dashboard sector in front of the coach.B: Mainloom, left in the front fusebox.C: Below the dashboard for the direction indicator switch.D: In the middle of the coach in the sleepingcompartment.

This fuse/relay panel exists out of 2 panels. The toppart is used for the electronics of ABS,ASR, AVS and integrated retarder.

E: In the connectorbox above the engine.F: On the panel above the batteries.G: In the AVS channel, right and left in front of roofunits.H: In the AVS channel, right and left behind the roofunits.J: In the interior light covers near the digital clock.K: Near the preheater.L: Near the airconditioning condensorM: In the luggagecompartmentN: In the luggage compartment, behind the toilet.P: Extra luggagecompartment (rear right)R: Serveral in gearbox compartment

Z: Fuses on panel B, D, F, N.R: Relays on panel B, D, F, N.

Fuses and relays 000 upto 199: panel B.Fuses and relays 200 upto 259: panel D.Fuses and relays 260 upto 299: panel N.Fuses and relays 300 upto 399: panel F.

RD = RedWT = WhiteBN = BrownGN = GreenGS = GreyGL = YellowOE = OrangeZT = BlackBW = BleuPS = PurpelRE = Pink

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Wiring survey

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Annex 2: Operational form

Coach number ................

Motor brand ................

Motor speed ................ rpm

Date ................

Form filled in by ........................................................

measured addition reference valuevalue for graph

inlet pressure .......... 1 .......... bar abs.

outlet pressure .......... 1 .......... bar abs.

outside air temp. .......... NC

exhaust temp. .......... NC

front interior temp. .......... NC

rear interior temp. .......... NC

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Annex 3: Operational graph

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Annex 4: Temperature sensor resistances

Temperature in NC Resistance in Kohm

-40 328,40-35 237,70-30 173,90-25 128,50-20 95,890 -15 72,230 -10 54,890 -5 42,070 0 32,510 5 25,310 10 19,860 15 15,690 20 12,490 25 10,000 30 8,0600 35 6,5360 40 5,3310 45 4,3730 50 3,6060 55 2,9890 60 2,4900 65 2,0850 70 1,7530 75 1,4810 80 1,2560 85 1,0700 90 0,9155 95 0,7861 100 0,6775 105 0,5860 110 0,5086 115 0,4429 120 0,3870 125 0,3392 130 0,2982 135 0,2629 140 0,2324 145 0,2061 150 0,1832

Resistance tolerance limit: 3%