Lack of Heat C900

My 85' C900 Turbo had a problem with the heater control valve being stuck. I replaced this unit with a new one, and was expecting hot air when I turned the switch to hot, and the car was able to warm up a bit. Unfortunately, I'm getting sort of a luke-warm kind of air, and was wondering why that may be. There is no shortage of air flow (although the air stops flowing when the selector is in some positions) Also, the coolant is heating up to temp, the thermo is opening up(and I'm pretty sure the air is bled out of the system too)

Does anyone have an idea what this is? I personally think this could be a problem with the heater core. If it's not, what else should I check? I had a problem like this with my full size GMC van last year and it turned out to be a low coolant level.(but the coolant is filled in this one)

Also.. can someone tell me why the fan motor runs in some air distribution positions and not in others?

I'd like to get these things fixed asap before winter is upon me, and I'm w/o my SAAB!

Thank you much!

-Larry

Reply to
LC
Loading thread data ...

Did you get a kink in the hose anywhere? Also are you sure the connecting rod from the heater knob to the valve behind the dash is connected?

Reply to
James Sweet

Why are you sure? What did you do to bleed air out of the heater core?

Most likely air in the heater core.

It is meant to do that.

Reply to
Grunff

Did you get the linkage rod back onto the valve? You can check through the left speaker grille in the dash.

Reply to
Dave Hinz

Dave

Yeah, I put it on there myself, and turned it up and down a good number of times to make sure I had it on right. The selector on the new ones is pretty much idiot proof. It attaches to the control valve one way, and 1 way only...

To answer Grunff and James's questions

A kink in the hose?

I'm pretty sure I didn't get that. I've got pretty decent air flow coming out of the vents.

Why are you sure? What did you do to bleed air out of the heater core?

I'm not sure. I've never had to bleed air out of a coolant system before. Is bleeding air out of the heater core different than bleeding air out of the coolant system at the thermostat housing?

What I did was open up the valve before the thermostat opened, and closed it once i saw some antifreeze flowing out. Initially, I had figured that filling up the coolant system completely would fix my issue, but that hasn't worked either.

Most likely air in the heater core.

If that's all it is, wonderful! I just wish I were more in tune with how to fix these things! I can fix computers, build networks, architect email systems, peoplesoft environments, etc. But with cars, I'm semi-adept at best.

Reply to
LC

If the valve is definitely open, and you have the correct thermostat, then I'd say it's an air-lock.

You can usually fix by revving the engine with the valve on max. If that doesn't do it, then you may need to force beeld the core. You do this by disconnecing both hoses, and connecting a garden hose to the core. Flush it through with plenty of water at high flow, then reconnect the hoses.

Reply to
Grunff

I drove it about 10 miles last night, and was driving steadily at about

50-60mph. most of the trip, and that didn't fix anything. I'll try opening the bleeder valve and revving it. The pain is that most of these things take 2 ppl to do.
Reply to
LC

Grunff;

Would a coolant flush & Fill @ my local SAAB dealer take care of this problem?

-LC

Reply to
LC

The fan should be running in all posistions except 0. In it goes on a "4th" speed.

Reply to
SmaartAasSaabr

So what would make the fan stop in positions other than ?

Reply to
LC

Possibly, but it really depends what the problem is - you need to investigate further. If the revving doesn't work, then you really need to hook up a garden hose to the heater core and flow water through it; this will tell you if the valve is stuck or there is a blockage.

Reply to
Grunff

Grunff,

Considering that I just replaced the valve with a brand new one, that's why I initially thought that it most likely might be the heater core.

So I think I'll try your test. What will a clear(non-blocked) result look like, and what might one that has some degree(even heavy) blockage look like?

Thanks!

-LC

Reply to
LC

Yes, I realise that, but it really could be one of a number of things. The new valve could be blocked. The core itself could have a blockage.

If it's clear, it'll flow very well. If there's much of a blockage, you will get reduced flow.

With the water running, turn the heat up + down. The flow should increase and decrease accordingly.

Let us know the results.

Reply to
Grunff

a blown resistor for speed 1 2 or 3 I would think. However, the fan is very quiet at speed 1 and to a lesser extent 2. If you move the fan speed control higher you should see a difference, except in the big which is always a speed "4". see if you feel air moving in when the car is stationary in speed 1.

Reply to
SmaartAasSaabr

I tried this... looks to be pretty clear. The core was in near pristine condition when I took it out the other day. Once I put the water on, there was about a 2-3 second delay till I saw fluid coming out of the bottom port. After that, it took about 30 seconds to clear all the antifreeze out of the core, and flowed well throughout the test, and I put the hose up to both ports, and water flowed well going either direction.

I think I got it bled correctly now.. I shut the screw when the fans were running.

We'll see on the temperature of the cabin air tonight once the ambient temp outside goes down.

I didn't turn the heat up and down.. It was set to full heat the whole test.

Reply to
LC

Well, sounds like your core is clear, and full of water. I'd hook it back up, run the engine for a while and see what happens - if you still don't get heat, then I'd start looking at the thermostat.

Reply to
Grunff

Okay.. I'll have to try that tonight and get back with you. As far as the thermostat goes.. the engine isn't overheating, it's opening up properly, etc. Is there a saab-specific reason you think this could be the culprit?

Reply to
LC

Yes, your engine uses a magical 3 position 'stat.

Cold: coolant circulates through block + heater core, not rad. Hot: coolant circulates through block, heater core + rad Too hot: coolant circulates through block + rad

The idea being if the engine is too hot, you don't waste precious time circulating the coolant through the heater core.

When your engine is at working temp, do the core in/out hoses get hot? As hot as the rad top hose?

Reply to
Grunff

Other possibility is the water pump.

If the pump is deteriorated (and they do sometimes), the flow will be enough to maintain circulation through the engine, but outposts like the heater matrix suffer from reduced water flow.

Not sure how you can test it, but they're not that expensive to replace.

Steve

Reply to
Steve Shuttleworth

Yes, both the top and bottom hoses get hot. Are they as hot as the top radiator hose, of that I am not sure.. I'll have to check on that one. Is it possible that it's only working on the cold and too hot positions, and not the hot?

Reply to
LC

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.