1996 850 climate control non functional

[dosbricks]

Gentlemen,
My 1996 wagon had sudden onset of no control of heater or A/C. It's stuck with blower motor running fast and heater is on. No response from any controls including A/C not cycling. I have been searching the forum and the consensus seems to be that when all control is lost it usually means the ECC is shot. This is the full automatic ECC with the green plugs on the back--part# 9166550.

I had blinking code lights about six months ago but I blew out the temp sensors above the grab handles and it seemed to pretty much alleviate that. I have removed the ECC and opened it up and removed the circuit boards to examine them for burns/overheating but everything looks normal.

So should I just proceed to ebay and order a used ECC? or do you have further suggestions?--BTW, I'm a bit elderly and somewhat electrically challenged but I do have a digital multimeter. Thanks.

dosbricks

[Ben850]

I will be delving into my 1996 Turbo wagon for an anomaly that showed itself when it became cold.
I had learned that this recent owner I had purchased the car from had hard wired a switch to the blower motor last winter.

The motor itself had a bad bearing. Sending direct unfiltered current to it was not helping.
I had swapped the ECC unit and power stage resistor after removing the hard wired switch and after clearing a check engine code, things were working again for a bit.

Things have failed again, in that I have no indication of any power to my ECC unit. No lights, flashing or otherwise.

I have three power stage units on standby that are the correct part #9134192. I will check the parts with a multi-meter this weekend for problematic indications.

I will post back anything that may be of help to your situation, as well as to my maintenance thread.
Wish us luck.

[jreed]

Dosbricks-- Does your ECC still give blinking lights? If so, you might want to build a little LED reader and see what error codes the ECC has stored. It may be that the ECC is dead. It could also be that the blower motor power transistor is shorted.

[Ben850]

Dosbricks-- Does your ECC still give blinking lights? If so, you might want to build a little LED reader and see what error codes the ECC has stored. It may be that the ECC is dead. It could also be that the blower motor power transistor is shorted.

No. No blinking lights.
I had mentioned in another thread that the ECC unit came back to life. It had come back without blinking, only the normal indication lighting of AUT and REC, respectively when switched.

I know my system has been altered by a self proclaimed fixer. I have to find the depth of his fixing. there are other indications of rerouted 12 volt fuse-able links that are subject.

Updates to come.

By the way, I had done all of these things for my '93 sedan two years ago. The ECC unit was in need of replacement for sure.
The codes I had read from the OBD-I indicated a bad passengers side temperature indicator.
The fan worked, but was noisy so I had replaced it as well.
Everything works in the sedan to this day, almost two years later. Including the A/C which only needed a charge.
I am driving the sedan at this point this winter. I had forgot how much I like it as well.

All will be fixed. I will not allow it any other way. (Let us hope my exuberance is helpful to me.).

[dosbricks]

jreed, there are no blinking lights. To avoid confusion with Ben850, my system has not been altered in any way.

Would a shorted blower power transistor cause loss of all ECC controls? Does this transistor fail because of aging blower with resultant worn bearings? I have 160k on this wagon, so I'm sure the blower has seen better days. It's presently stuck running at pretty high speed. No abnormal noise from it.

On a side note, my wagon looks just like yours, white, cherry condition , always garaged, but NA not turbo.

[Ben850]

"

On a side note, my wagon looks just like yours, white, cherry condition

I like 'em too.

"jreed" and myself have nice white wagons. I was fortunate to get this buy.
Here
https://www.matthewsvolvosite.com/forums ... 35&t=56550

I haven't taken any photos lately, but there will be shortly. I had wanted a Turbo wagon, but white sealed the deal.

[dosbricks]

Nice cars Ben. To all other readers--sorry I got this thread off topic. I would still like to hear whether I should approach my problem by replacing the ECC or approach from a different angle. Thanks.

dos

[Ben850]

Nice cars Ben. To all other readers--sorry I got this thread off topic. I would still like to hear whether I should approach my problem by replacing the ECC or approach from a different angle. Thanks.

dos

Sorry to go off topic. I will post what I can this weekend.

[jreed]

DosBricks-- Hopefully Ozark Lee will weigh in with his opinion... he's seen it all. It could be that the ECC has failed, although your inspection of the inside didn't reveal burned semiconductors or exploded / leaky capacitors, so the diagnosis can't be conclusive. At the 160K mileage on your car, it is possible that the blower motor would be worn out (at least, the blower on my '97 855 was squeaky and pulling excessive current at ~100k miles), which may also have caused the blower motor power transistor to have shorted. One approach would be to replace the ECC with a known good unit and see if the system comes back to life.

[dosbricks]

DosBricks-- One approach would be to replace the ECC with a known good unit and see if the system comes back to life.

Just to follow up, I did as suggested--purchased a used ECC from ebay--and the entire system returned to full functionality. A tip of the hat to jreed and all those other posters whose opinions I read while searching past threads on this. My thanks to all.

dos