Hey guys....well it's so damn cold out (Michigan), and I must get my heat working properly or I'll be a damn icicle soon.

Okay well ever since I bought the car, and I start it cold.....the guage gradually goes up to about 220 then as soon as it hits that point, it very quickly moves down to the normal (160) mark. Is this even normal?

I had my T-Stat replaced about a year ago....and that definitely helped my old heat problem. I'm thinking this may be the reason? I had my heater core looked over a couple months ago, and it was said to look fine. My coolant level is always normal, and I never overheat (<3 air dam lol). But everytime I buy a new t-stat from Autozone, it's faulty. What temperature T-Stat should I buy for the winter?

judging from all this, what do you guys think?

Thanks a lot

 

Are you also having either problems with the vacuum flapper doors for the HVAC system or with engine idle? It sounds to me like you have either a lack of or too much vacuum at the heater control valve, or maybe it is stuck. They are cheap to replace (got mine for $16 and change including NYS sales tax) and the vacuum lines are cheaper to replace.

 

If everything checks out ok, then I would ask what T-stat did you put in the car. A 160* or 170* T-stat would not produce hot air, only moderately warm air for the passenger compartment. I have that problem out here in AZ becasue of my 160* T-stat.

It's actually not much of a problem in AZ.

 

I forgot he mentioned that, however, I doubt that the heater core for the '93 Cavalier is much different than the one in an F-body, and the one in that car works pretty good with the coolant temp being around 130*. But I must say that a 160 thermostat is a little too cool for the ECM... that is right at the border where the ECM enters/exits closed loop (gas saving) mode. And as for the temp drop, that is normal if your cooling fan(s) are working as they should.

 

what temp t-stat are you using?

 

Well I had a shop install it last year back when I knew 0 about my car. I'm guessing it's a 160* cuz my normal operating temp is 160.

And yes, I've been having problems with my car idling way too low in drive/park.

This Heater Control Valve, I'm not familiar with it. Where's it located exactly, and what does it do?

thanks!

 

There should be three or four small-diameter coolant lines running near it, with three of them connected to it. It is hooked in between the intake manifold and the heater core and is just above the line running to the core from the water pump. It looks like a round T-like object with three hoses running into it...

 

Well this weekend I replaced my HCV and *195 thermostat ( what a mess ) It seems a bit warmer.....but still not as hot as it should be. One thing I forgot to mention in my previous posts is that when I put on my heat on the front defroster, the drivers side is always warmer than the passenger. It's still the same. What could this be a sign of? Thanks

 

Sounds like you need a diagram for the vacuum hoses. On the TGO main page, go to Tech Articles/Electrical. There, you will find a link to "86 Fbody wiring diagrams". When you get to the site, scroll down the page until you find a section on Air Conditioning, and at the bottom of that section is the link to where you will find vacuum hose data.

It sounds as though you have a clogged hose, be it in the HVAC intake hose, or somewhere in the plumbing along the line. There are two vacuum hoses in the engine compartment for the HVAC system. Both are black in color. The intake one is located near the wiper motor and the one for the HCV, well, you know where that is. They join the main wire loom that enters the pass comaprtment behind the pass fender that is also for the ECM and a bunch of other items, and they tend to look like the other wires due to their size and color.

And don't forget to drain the coolant the next time you need to open the system... It saves a lot of mess...

 

thanks maverick,

a few questions:

What exactly could this hose be clogged with?

What can I look for to see which hose is clogged?

Once/if I find this hose, what's the best way to unclog it?


I appreciate it dude :hail:

 

O crap, after looking at that diagram....it makes me think. My "hot and cold" lever gets stuck when I move it to the hot zone. Everytime I switch it to the far right, it has major tension and it takes me 5 minutes to get it to stay there without pullin back to the left. I eventually get it stuck on the right, but this makes me wonder......hmmmm :|

 

Pull the hoses from the connectors while the engine is running. Simple as that. If you don't feel a strong vacuum, then you have a partially clogged hose, and if there is no vacuum, then there is a clogged hose or that hose has not been activated by the vacuum switch on the control panel. As for what can clog the hoses, I have no idea. Also take and check each hose carefully for breaks, cracks, melting, etc. any or all of the above can mean less vacuum for the engine and that can spell trouble on the highway.

And as for the temperature selector lever, pull the pass side hush panel (the large black one at the bottom). Right in front of you there will be a large black box, which is where the heater core is located. At the bottom of this box is the temp door lever, which is operated by STEEL CABLING (highlighted because this is the only function NOT vacuum driven) similar to that used for bicycle brakes. Check both levers to see if they move freely and then check to see if either end of the cable is rusted to the outside of the casing end, which is also steel, I believe. You can use a penetrating oil to free the cable, but do NOT use the oil on the levers themselves. You may want to find a way to unhook the temp door end of the cable and see if the door can be moved by hand. If it can't, then go to the trouble of removing items until you can open the heater compartment (this is well documented by many) so you can possibly clear the leaves and whatever else is in the ducting out because it is blocking the door and the heater core. I have known this to happen.

That is about all I can help you with for right now based on the info I have been given. I will continue to help until I have nothing else to give.

Oh, and you will want to lube the temp select levers with white lithium grease (oil is not good for plastic).