1994 850 Heat Has slowly ceased blowing. Heater Core? Or...?

JamesDinCT · Post by **JamesDinCT** » 01 Jan 2019, 19:53

I have owned my 94’ 850 for at least five years now. I think from just about the start my heat didn’t really blow on the 1st of the 4 heat fan settings. 1 being the lowest and 4 being the highest heat setting. At some point last year my heat stopped blowing on the 2nd setting. I’ve had to have it blowing on 3 or 4 to get heat. This was loud and annoying but I had heat. When on the first two settings just a tiny bit of hot air would sneak out of the vents. You could feel it if you put your hand to the vent but not otherwise. In the past few weeks when I put the heat on 3 or 4 I could hear squealing and noises coming from the passenger side vent areas, usually just when I turned the heat on but sometimes randomly. A week or so ago the third setting stopped working and I was stuck with just the 4th option. More noise and squealing until last night the 4th setting stopped blowing as well. Now I have no heat other than just the tiny amount that leaks out of the vents. Now some other info. It hasn’t happened in a while but I used to have little bits of fabric blow through the vents. I think it’s from the firewall. I looked recently and my car had no cabin air filter at all. Just a big hole with a bunch of the fabric, leaves, and dirt around it that anything can fall into. Guessing maybe mice made a nest at some point? Wondering if it could possibly just be clogged up somewhere? Other thing is recently my coolant warning light had been coming on sometimes. I topped off my coolant tank and it still comes on for a short time when I start the car, then turns off usually. Lastly over the summer I noticed that there was a ton of water in my passenger floor mat and below it. I’m a smoker and have the passenger window open even during the rain sometimes to vent the smoke so I thought I just had an unusual amount of rain come in maybe. I usually have a ton of stuff in the passenger seat and on the floor in that area so maybe this has been happening ever since and I just didn’t notice. Last week I noticed it again for the first time since the summer. More water on mat and below it. Again thought maybe rain but realized this could also be pointing to a problem. Did a google search and realized this is a symptom of a heater core leak. Does this sound like its 100% a heater core leak or is it possible I have a different issue? It sounds like the heater core is a not easy or cheap to replace so really hoping it may be a less expensive fix. It’s pretty damn cold here near Boston in the winter and I can’t go without heat too long. I don’t smell coolant which I guess is another symptom of a heater core leak so that’s good but concerned about the warning light and losing coolant without knowing it. Any help or suggestions would be appreciated. I have virtually no ability or knowledge as a mechanic so layman’s terms and instructions will be necessary if anyone has any help to offer. Oh also my crank shaft sensor is faulty and causing stalling. I assume this is totally unrelated but figured I would mention just in case. If anyone is near East Boston and can help diagnose that would be awesome too. Thanks!!!

Sommerfeldt · Post by **Sommerfeldt** » 02 Jan 2019, 04:47

So, you have 2 issues.

1: The heater core won't make noise, squeal or blow things through the vent. That's your fan and fan motor, which have seized. Replacing the fan motor (either with fan as an assembly, or just the motor if the fan is still OK) is not a big deal. Remove kick panel on passenger side, remove wiring loom from the housing, 3 torx-screws and it's out. Reverse order for assembly, as usual.

2: Losing coolant and wet carpets usually only means one thing - heater core needs replacing. That's a bigger job, but not at all impossible if you take your time, are careful and have a relatively temperate place to tinker on your car. There's a few write-ups and threads on heater core replacement around, so take a peek in the repair database.

Oh, and get a cabin air filter and holder, and get them on that hole with the mice in it.

Even genuine blue box holder and filter aren't expensive.

- S

JamesDinCT · Post by **JamesDinCT** » 02 Jan 2019, 13:19

Thanks so much for the reply!!! Would you say you’re 100% sure it’s the blower motor? I’m going to order one if so and try doing it on my own. All the ones I can find have the wheel assembly attached. The fan itself is separate right?

As far as the heater core I’m not so sure I can do that. Theoretically can I not fix that for now and just replace the blower motor and at least have heat for the time being? Not sure how much $$$ I want to put into the car right now.

The housing/holder for the air filter seems to be there from what I can tell which makes it crazy that the filter is missing. I never imagined there might not be a filter in the car or I would have checked a long time ago. I’ll grab one of those! Unfortunately no temperature controlled space to work in. Just the side of the road

!

Thanks again.

Sommerfeldt · Post by **Sommerfeldt** » 02 Jan 2019, 13:32

Well, I'm as sure as I can get without actually being there.

Squealing, noise, and no air coming out of the vents, is the blower motor. You need a new one. It's easy to replace, and if you want to go cheap, you can get the whole assembly for about $50 on eBay. Cheaper from a junkyard, I'm sure.

Also, you can't have heat without a functioning heater core. If you don't replace it, you'll keep leaking coolant. So you'll have a wet, cold car with a danger of overheating the engine if you lose too much coolant. Changing the blower motor will get you air, and changing the heater core will let you heat that air.

A heater core from Swedish Car Parts (not the best stuff, but better than broken) is $30, so even cheaper than the blower assembly. It's more work, but you can get both of these things done for $100 if you do the work yourself. Plus another $10-15 for the cabin air filter.

- S

Sommerfeldt · Post by **Sommerfeldt** » 02 Jan 2019, 13:53

I should clarify - changing the heater core isn't hard. It's a little fiddly, and you have to pop back and forth between the driver and passenger side to remove 4 -5 torx screws, and clamp some heater hoses shut. Anyone can do it with a T25, a T15 and some patience.

- S

dj_v70 · Post by **dj_v70** » 02 Jan 2019, 15:39

I don’t know this specific model, however, in my experience:
a) squealing heater is the heater motor itself
b) most models have a heater fan resistor for changing fan speed. The fan speed issue is the resistor in that case. It probably died due to dying motor that was drawing excess current. Resistor generally controls all fan speeds except position 4.

crlande · Post by **crlande** » 02 Jan 2019, 18:08

You should get inside the blower compartment and clean the debris out first. The debris maybe causing some of the screeching. Then look at the blower motor resistor and/ or the blower motor.

JamesDinCT · Post by **JamesDinCT** » 02 Jan 2019, 18:35

Thanks for all the help guys. So as a mechanic, and taking things apart and putting them back together in general I would give myself an F. Im pretty bad. How do I get into the blower compartment? Is that found where the heater core and motor are under the dash I assume?

I believe the 850 has the resistor. It sounds like if this is bad it would be because of the motor being bad as well? So I’m looking at replacing the core, motor, and resistor.

Post by **abscate** » 02 Jan 2019, 19:34

The path to Nirvana is found in watching the videos by Mr Volvo - aka Robert Spinner, user name here rspi

He will have a video on blower replacement on his You Tube channel for P80 - your model

crlande · Post by **crlande** » 02 Jan 2019, 19:53

You can pull the carpet back and remove plastic shields on either side to view the core which is behind the radio. This is easy to do and you will see wetness indicating replacement. Resistor and blower motor are under and behind glove box and knee bolster. Then make your decisions.