Greetings all,
This is my first post, so I thank you in advance for helping me out.

Ok I have a 1994 850 Turbo Wagon and my problem is the heater. Here's what happened.

A while back the heater was a little fidgety and once and a while the fan would stop working for short periods of time. It mostly happened if I had the fan on high, or automatic, which would take it up to high.

One day the fan just stopped working entirely. High, low, auto, nothing. Then about a month later, it started working again. Only this time it wouldn't shut off! The fan would blow at high speed constantly, whether the control was set high or low, off or on auto. I couldn't let the fan drain the battery so I pulled the fuse and forgot it.

Now a few months later, after I'm out of grad school and can afford to do some repairs on the poor old gal I've noticed one other weird thing. When I turn the dash lights all the way up, the instruments and radio light up but the climate controls dim all the way off. When I dim the lights down the opposite happens. Instruments and radio lights off, climate control off.

So I took this repair to a dealer to diagnose. They explained that the Climate control unit is faulty for sure, but it might not be all the problem. The $900 price tag for this dissuaded me to try this but then I also have a hunch its not the whole story.

Ok summing up soon. So I went to a boneyard and found another 850, the victim of a run in with some other less safe car I'm sure, and took out the Climate control unit. Considering it cost me 20 bucks, I figured a good gamble, and the chances that this climate control was shot too were worth that 20 bucks. I think its possible it could be shot too, but I think it unlikely to have the exact same problems that the old one had, and think it could be something else.

So I switched out the climate control units and all of the above things still happen. Now I wonder if there might be other causes for these problems. I understand there is another part that commonly fails, the blower resistor, could this be the problem, and would replacing it with a new part be a likely solution?

Any thoughts or possible solutions would be great.

 

Blower resistor (power stage) for sure. The lighting issue is a strange one - does it still do that when you have you fan fuse back in?

...Lee

 

Hmm. I don't think I've checked that but I will tonight and see what happens.

I suspected the resistor was the problem as it seemed to pop up on the forums here and elsewhere as a common problem.

I'll report my results after I fix it in the coming week.

 

https://volvoforums.com/forum/volvo-850-16/strange-heater-issue-29104/

I saw this thread just posted too, and I remember that my blower squealed a lot before it stopped working. I would think that the blower seized but like I said before, it does blow 100% now when the fuse is in. Replace the blower too maybe?

 

The blower on my Platinum started to squeak a bit but I was able to pull it apart and lubricate the bearings. The bottom bearing is easy, the top one is tough unless you pull the squirrel cage off. I just drowned it with WD 40, and ran it backwards and forward (once the blower is out of its mount the connector can be put on upside down to get it to run backwards) until it didn't squeak anymore. The blower assemblies cost somewhere around $185.00 and just the motor is nearly $100.00.

Even when the blower is just squeaking it is drawing a lot more current and it will ultimately take out the power stage.

...Lee

 

I tested the light issue tonight. I plugged in a fuse, the fan ran 100% as usual even in the off position. The lights function normally, all on at the same time, all off at the same time.

Does this help to diagnose any? Does this make it clear it's the blower resistor?

I'll be ordering one later this week, so I'll let you know if that does the trick.

 

Yes.

...Lee

 

So I just replaced my Resistor today on my '93. I also took out my blower motor to lube up the bearings and pretty much did what Lee said to do and just drowned it in WD-40 lol. I did notice something strange though that you seemed to have symptoms of. There are plugs all kind of "attached" to the blower motor housing, but they're just wires plugging into other wires, not going directly to the blower motor. I tried testing the whole thing out after replacing it, and I had the lights issue that you did, when the dash lights were off/dim, the ECC were on, but when the dash lights were on, the ECC lights went off.

Ended up being one of those plugs that is attached to the blower motor housing that I forgot to plug back in. As soon as I plugged it back in, it lit up like normal, and everything works well again.


Best of luck to you with your blower motor/resistor.

 

Well I finally got around to finding a new resistor motor. Instead of forking out the $140 for a new one, I tried my luck with one from a wrecking yard for replacement parts. Its a gamble yes, but I think given the resistor was only $10, I thought it worth it.

Anyway, I replaced the blower from another 850, and found an identical (I think) resistor from an 1998 S70.

So replacing all these parts, along with a used climate control unit the fan nearly works.

With all the stuff hooked up, all the fuses in and everything here's what happens: When I turn on the car, the blower starts turning for about 1-2 seconds and then turns back off. Testing it with the old fan it does the exact same thing.

So far I've not taken it out for a long drive to see if it comes on after a while or not.

Before this I had heat going, and if I turned the heat up or down on the climate control unit, the car would get heat or no heat correspondingly.
On some occasions the AC off light and off lights (right next to the lower right switches) on the climate unit would blink for a while when I turned the car on.

My question is, do you think this is the blower resistor still or could this climate control unit be faulty as well?

BTW whoever mentioned that the fan had problems was right, pulling the old fan I found it barely moved, compared to the replacement which turned just fine.

Any help would be great, as its starting to get cold out here!