Hi all, I have a 1993 850 GLT with the automatic climate system. I have good heat being emitted from the heater core, and the blower motor seems to work just fine. The system seems stuck on defrosting the windshield and I cannot adjust to the footwell area.

I pulled the codes and got 231 and 233, which refers to the Ventillation Damper motor and the Floor/Defrost damper motor. It seems awefully strange that both of these motors have gone, though I guess it's not impossible. I have been surfing a number of forums reading about the ECC and similar problems.I have a few questions...

1. Is it likely that it's the ECC unit itself and I should go ahead and locate a new ECC?

2. Is there a way to diagnose the ECC unit?

3. Should I just be going ahead and removing these motors for further testing?

 

Hi Maxbaby,

Greetings from Yokohama.

The ECC unit on 850s are noted for problems, most of which are due to fickle system performance. Before replacing the ECC unit, I would try resetting the codes and see if the system works normally. As for each question:

1. Is it likely that it's the ECC unit itself and I should go ahead and locate a new ECC?
If the system still wants to stay in defrost, even after resetting the codes & double checking the fuses/damper motors, you may want to locate a used unit at junkyards, on-line vendors, etc...

2. Is there a way to diagnose the ECC unit?
This one I am not sure. Haynes manual does not specify testing the ECC itself. But generally, if the ECC itself is shot, it should throw a code for "Faulty ECU". But self-diagnostic are not very reliable sometimes, and I assume onlyVolvo dealers/original manufacturer can test the ECC, with an exception of electronics geeks. Or, if you can locate Volvo factory manual, you may be able to diagnose it though the manuals are pricey.

3. Should I just be going ahead and removing these motors for further testing?
If the same codes come back after resetting the codes, it may be the damper motors. But as you say, it is highly unlikely that the 2 motors are shot, unless they were in close proximity and got watered, or somehow sharing the same wire, etc...

Also, it may be worth taking the ECC out of the dash, take the front panel and clean as much as you can with air duster/moist cloth, as well as re-connecting the electrical connectors. You'll be surprised how cheap it looks/feels, once you take it out of the dash. I also replaced the bulbs for illumination when I took mine off.

Wait until other guys reply to get better perspective, as this is my subjective opinion. My replies tend to be lengthy and end up confusing people rather than helping. Moderator Tech usually solves problems with mere few sentences.

Good luck,


JPN

 

Hi JPN

Thanks for the reply... funny how things work but before I sat down to read your reply, I had just finished pulling the ECC from the dash (thought maybe a disconnected wire??). So I did pull it apart and run some compressed air over the circuit boards and confirmed that the connectors to the circuit board were all still solidly connected, and then reassembled it and plugged it back into the dash...

... no luck... still doesn't work. I haven't reset the codes again, but I'd still bet it's gonna flash the 231, 233. I am leaning towards trying to locate another ECC, and if possible, the damper motors, and then plug everything in to see what happens...

... anyone with more information?... gladly appreciated.

 

Hello again,

Should you go for another ECC unit, make sure to keep the original. I once had to buy a switch **** for A/C, and had to pay $10 for that little piece of plastic[8D]. Many dash items are dealer-only parts, unless you can find one at a junkyard. I would still tryclearing the codes before spending $ on new ECC, unless you've already cleared them once. I would also check the damper motors for electrical connectors, and maytap them to see if they wake up. Visual inspection for the motors may reveal something.

I hope others jump in as well, as any opinion helps.


JPN

 

Hi, I just wonder whether it would throw a code if there was something stopping the motors from doing their job, maybe siezed/worn linkages or some internal obstruction? Try and find if they work when removed before paying for replacements.