No REC OR AC lights on ecc. 1996 Volvo 850

Jsadler · Post by **Jsadler** » 22 Dec 2024, 23:34

I’m struggling finding a problem with my ecc. I have a 1996 Volvo 850 and the terminals were hooked up backwards when jumping the car. The ecc unit blew and I thought the blower resistor did too. I first bought the ecc unit and plugged it into. The new one the lights turned on except the REC and AC lights. So I went down to the blower resistor. I replaced that’s as well and it did not resolve the problem. I’m not sure what it could be at this point so any help would be appreciated. The blower motor is good and that is also a new part. I was thinking relay but I took that apart and nothing seems to be wrong or blown.

Post by **jreed** » 23 Dec 2024, 05:33

There are several different revisions of the ECC unit... just checking to be sure you've got one that is compatible with your model year/wiring harness.
Some background info on ECC versions/revisions: viewtopic.php?t=83674

Jsadler · Post by **Jsadler** » 24 Dec 2024, 10:52

Do you know how I would check to see which specific one I need?

Post by **jreed** » 24 Dec 2024, 16:13

I would guess that the best bet is to replace with the identical part number. If you don't have the original, since your car is a 1996 it's a good bet that control module 9166550-5 is correct:

: Screenshot 2024-12-24 at 18.09.54.png (182.99 KiB) Viewed 203 times

Jsadler · Post by **Jsadler** » 31 Dec 2024, 18:57

I checked and the sticker on it says 9166550 W627K. The unit did also come with its own harness plugs. I don’t think those would do anything switching them out. I did order this part off eBay from someone with good reviews. There are returns available as well. It says it was tested. Not sure what to do from there.

Post by **jreed** » 01 Jan 2025, 07:00

Does the system work OK except for the orange indicator lights on the AC and REC switches?

Jsadler · Post by **Jsadler** » 01 Jan 2025, 14:06

Yes the heat works if I plug in the power to the unit into the blower motor. Just those lights don’t turn on and there is no power coming from the red and blue wire to the blower motor. Would it be a problem with the MOFSET? Just those two lights don’t turn on.

Jsadler · Post by **Jsadler** » 01 Jan 2025, 14:09

I bought the car with working heat and a/c controls. I don’t have the old ecc unit because it was thrown away. It was noticeably blown and shorted out to me and I’m not an electrician. I did replace the clutch and had to unplug lots of wires and drop the engine about half a foot so that may have caused something. It was jumped incorrectly before the clutch was replaced.