Help with Air Con Problem please?

[Robos Landy]

I have a 2003 Td4. I noticed that the air conditioning did not cut in when I press the switch, a garage checked the system and said the pressure was spot on. I have changed the relay in the engine fusebox, checked all the fuses, changed the fan control unit from another vehicle, (where it worked) checked the fans are free spinning,and still nothing! This is really staring to get to me now:banging:. Can anyone help with any advice?

[dann]

There's a pressure sensor/switch screwed into the aircon pipework just below the battery tray, check the connection is clean and secure.

With engine running and aircon switched on you should find a 12v feed to the aircon compressor clutch:

if so then switch off and check resistance of the clutch windings as they may have become open circuit.

If no 12v feed to clutch then the operating system will need to be checked again.

[odonnellkevin]

check the switch on the dash, might just need a clean. Mine is dodgy and I have to switch it several times before it will work. Or move up here to scotland and you will never need it.

[Robos Landy]

There's a pressure sensor/switch screwed into the aircon pipework just below the battery tray, check the connection is clean and secure.

With engine running and aircon switched on you should find a 12v feed to the aircon compressor clutch:

if so then switch off and check resistance of the clutch windings as they may have become open circuit.

If no 12v feed to clutch then the operating system will need to be checked again.
Where can I find the compressor clutch? Is it actually on the compressor?

[dann]

The compressor clutch is electro-magnetic and is located at the drive belt end of the compressor just behind the drive pulley. You need to take off the under panel and look underneath, take care with rotating components.

[saltireblue]

Or move up here to scotland and you will never need it.

:D:D

[Robos Landy]

Booked the car into Air Con Specialist. He has checked all circuits and everything is fine aprt from the main ECU is not responding!! This is now being checked, lets hope it a simple re-program and not a new ECU required. Thanks for your advice. Rob

[dann]

OK. Good luck.

[happyhippo]

I had a similar problem. Aircon just stopped working. A specialist diagnosed that the thermostat had failed. Apparently this is located behind the dash and required stripping out. Difficult to argue with so I just had to swallow the cost which included the new part. At the same time I asked for the receiver/drier to be renewed. It all works well now.

[Robos Landy]

I wiil make sure that they have checked this. Thanks

[Robos Landy]

I have a 2003 Td4. I noticed that the air conditioning did not cut in when I press the switch, a garage checked the system and said the pressure was spot on. I have changed the relay in the engine fusebox, checked all the fuses, changed the fan control unit from another vehicle, (where it worked) checked the fans are free spinning,and still nothing! This is really staring to get to me now:banging:. Can anyone help with any advice?
Well it has been away for a week now to an expert!!!! He has checked all sensors, connections and had the ECU tested and re-programmed. Guess what? It still doesn't work. Just have to keep the windows open now. Is there a second ECU behind the instrument pack? On the Disco TD5 its called a BCU body control unit. Is this on the Freelanders?

HELP!!!!!:eek:

[Chaser]

you haven't said if the clutch on the compressor is engaging?

[Robos Landy]

The power has been checked to switch, sensors, clutch, relays, fans and all work. If you connect a direct supply to the compressor it activates. I am at a loss as to what is wrong. This is why I ask if there is a second ecu behind instruments. I have looked in Rave and printed circuit diagrams and it states a CAN-BUS connection between instruments and ECU. Surely this must mean there is something there. Also, what is a Can-Bus connection?



Robos Landy

[dann]

'Rave' page 581 gives a description of the link between AC operation and instrument pack processor unit. CAN-BUS is a simple low cost method of moving systems data between ECUs around the vehicle, easily recognised as a pair of thin cables twisted together.

For AC to operate the engine management ECU must provide two earth paths 1. To compressor clutch relay and 2. To the cooling fan controller.

I would carefully remove the instrument pack and check that the two multiplugs are securely plugged in to the processor.

[Robos Landy]

Well, here we are with fully working Air-con. Having sent it to a Specialist Vehicle Electrician he fully tested by computer all of the system. The result NO CAN-BUS output from the instrument pack!!
Apparently this unit connects with every ECU fitted within the vehicle and its failing is a common fault. Usually leading to ABS faults, but sometimes, as in my case the Aircon.
Well happy now, just the bank balance suffering as £600 to fix!!!!!

Thanks for all your suggestions as to cause.

Rob:)