850 climate control in auto not working

tasatterly · Post by **tasatterly** » 14 Jan 2007, 20:50

My 93 850 ECC works when the car is running except for when the fan switch is placed in the auto position. Fan works fine in manual, but when I turn to auto, the fan stops. Here is the interesting part. When I turn the engine off and turn my ignition on, the ECC works with fan switch in the auto mode, but if I start my engine, the fan stop blowing, and both indicator flashing for 10-15 sec.

Any help would be much appreciated!

thanks,

Post by **Ozark Lee** » 15 Jan 2007, 07:09

Dump the codes from socket B-1 and post them. Once we have the codes we can likely figure out what is wrong.

...Lee

tasatterly · Post by **tasatterly** » 15 Jan 2007, 18:06

Lee,

Thanks for the prompt reply. Unfortunately I'm new to the Volvo diagnostics world, I don't have a clue where to start with socket B-1 and downloading codes. Any additional guidance would be much appreciated. Are you referring to an OBD procedure? I don't own an OBD device but now may be the time to purchase one, again recommendations would be welcome. I did download the free 95 850 manual from matthew's site and am reading up on the ECC. I also saw a forum article that referred to trouble codes (DTCs?) that could be read from the two flashing lights on the front of the ECC (the REC and A/C lights I think). I'll try this also.

Look forward to hearing back on this topic.

Post by **Ozark Lee** » 15 Jan 2007, 18:44

Actually, since you have a '93, you do have OBD device. You just don't know it!

At the top of this page there is a "for free" service manual and it describes how to pull codes on your car. The sockets are located under covers marked A & B directly next to your windshield washer fluid filler.

Back to 24,

...Lee

tasatterly · Post by **tasatterly** » 16 Jan 2007, 21:00

Lee,

Only one DTC, 1-3-5. Any thoughts why this allows the ECC to run fan in AUT when the engine is not running but the ignition switch turn to ACC position? The fan still runs fine in manual mode with the engine running.

thanks,

Post by **Ozark Lee** » 17 Jan 2007, 07:02

The 1-3-5 code is for no signal from engine coolant temperature sensor. The automatic fan speed is determined by, amongst other things, the coolant temperature. It doesn't want the fan to come on and blow cold air in your face when you first start the car. Absent that temperature signal it disables itself.

Does your temperature gauge on the instrument cluster work? If so there is either a loose connection or a broken wire between the instrument cluster and the ECC. The wire is Green/Grey and goes From pin A-26 on the instrument cluster and pin A-23 on the ECC unit. Assuming that no one has been messing with the wiring I think I would start by pulling the ECC head unit and then spray all of the connectors with a good contact cleaner.

If your temperature gauge on the instrument cluster doesn't register then the problem is likely the coolant temperature sensor itself.

...Lee