big500

The aircon isnt working on my UK Wagon , The sysyem is fully charged and the solenoid / temp sensor on the compressor work ok.
There is an aircon relay mounted in the relay box behind the battery and on testing I find that the ground connection to operate this relay is not present. On following the wiring diagram back it goes through an "AIR COND RELAY" and then back to the ECU. Does anyone know where the relay is located ? or has anyone any experience of this problem ??

Many Thanks

Steve

Ian D

Steve

Fitted an aircon kit to my 98MY turbo 2 weeks ago and the kit included 3 relays, all mounted in the relay box you mentioned just behind the battery. I remember one of the relays is the air cond relay.

Also check the low pressure switch on top of the receiver drier is ok, unplug it and short the 2 terminals out and see if that helps.

Other than that check the obvious fuse, but if the aircon light comes on it is probably not that.

Ian

big500

Thanks for the advice Ian but I have already eliminated the pressure switch , temp sensor (mounted on the side of compressor), solenoid and the 3 relays which you mention.I think 2 of the 3 control the radiator fans and the 3rd one operates the engage solenoid on the aircon compressor. If I remove the 3rd relay and test the wiring I get the fused 12v supply for both the load ( compressor) and the relay coil. If I short the 12v feed to the load ( as the relay would do when it operates) the aircon works and the temp goes sub zero! However the earth connection on the relay ( which it needs to operate)is not present.. It appears that this 12-ve feed goes through yet another relay contact and then to the ECU ?? I can only assume that when you fitted yours the wiring to the relay box was present on the car and fortunately the 12-ve supply is fine on your car.I have removed all 3 relays and tested them with a 12v supply and a 5A load ( main beam element of a headlamp bulb 60W rated )

Can anyone else offer any advice

Huxley

There used to be a Relay on the drivers side bulkhead on some of the early scoobs might be worth a check.



Huxley

StephenPope

This might seem very obvious, however when I got my MY98 uk 4 door, I thought mine was not working as the green light was not coming on some times. I then switched the fan up to setting number two and it came on. I switched it back to setting one and realised that you have to be careful that it is actually propertly in the middle of setting one (or slightly towards setting two!) Hope this makes sense and good luck!!!

big500

Thanks Huxley , I am taking the dash out in a couple of weeks to change the heater matrix so I will check the relays on the bulkhead when I do.This sounds like the relay I may be looking for can anyone help with its identification or specific location please ??

Thanks again

Steve

big500

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scoobyboy

been there with a similar problem on a my98 it to had lost the earth traced it all the way back to either the ecu or the temp cut out sensor in the aircon matrix in the air box. it did unfortunatly turn out to be the ecu not giving it the ground. i have since then had two more in with exactly the same problem the ecu at fault.
if you can see if you can borrow an ecu from someone because whilst probing we did manage to blow up the temp cut out sensor!! it seems it's not keen on having a probe up it's jacksy to find the earth!!!!!

big500

Thanks Scoobyboy your reply was exactly what I was thinking ( but didnt want to believe !) I will test for the earth output directly at the ecu. If its not there then presumably its a transistor , ic ,or feed at fault ?? Does anyone know if the ecu can be faulted / repaired down to board level , or is it a "disposable" item ??

fortunately winter coming soon !!!!


Steve