I just bought a '96 850 T5, and noticed that the A/C compressor is on at all times. The car is equipped with electronic climate control. I pulled the A/C relay out but the compressor clutch still engages any time the ignition is on, even if the engine is not running. Any ideas on how to find the problem?

 

Does someone have it direct wired with another relay?

 

I looked for any hacked-up wiring, but I didn't notice anything. Anywhere in particular I should look? The A/C relay seems to function normal. When the A/C switch on the ECC is turned to "AUTO", the relay clicks.

I hooked up the Volvo System Tester, and in the data stream the A/C relay is always "on" even if the switch on the ECC is in the off position. There are seven DTC's stored in the ECC, but they are all for damper motor operation and interior temp sensors.

 

Is the ECC set to defrost?
If so that may be why.
If not then the ECC module might be bad.

 

It stays on no matter what mode is selected. I think Im going to take apart some of the dash and look through the wiring. I hope there is nothing wrong with the ECC module, those are expensive!

 

Sounds like you are on the right track. I'm betting on wiring or a bad ECC. HOpefully it is a simple wiring issue. Good luck!

 

I figured it out. There were two wires under the dash going to the A/C relay that were melted together. This consequently bypassed the relay and would engage the A/C clutch anytime the ignition was in position 1 or 2. The previous owner had the evaporator and compressor replaced, so I think the melted wires could have been related to the compressor failure. Everything works great now, and the car is faster now that the compressor shuts off at full throttle.

 

SWEET [sm=signs007.gif]

 

Good job troubleshooting!

 

Glad you found the problem.

 

Yipee!

I have finally found a person who cannot switch their A/C off.

I have the same problems though I am sure the cause is different. I cannot isolate a 12v supply that appears on both sides (should be only one side) of the low pressure switch connector after the electrical connector is removed from the pressure switch.

Therefore, I am getting ready to change the ECC to see if that is the problem - and I will have my fingers tightly crossed that a faulty ECC is the problem.

 

I will keep my fingers crossed for you.

 

Thanks Tech,

Much appreciated.