Heat not working please advise..........thanks

[demarpaint]

I have a 95 Caprice and the heat blows luke warm after about 30 minutes driving. The engine seems a little slow to warm up but does reach normal operating temperature after about 20 minutes of normal driving.

No over heating issues no blockages. How do I check Heater Control Valve and Thermostat? We are expecting snow and I am dead in the water w/o the heat. The problem started a few days ago.

Thanks!!!

Frank D

 

[TimVipond]

If you've never replaced your thermostat, you are probably past due. If it fails in the open position, it will be harder for your engine to reach optimal high temperature. This would be the place I would start.

Also, your heater core might be slightly plugged, so it will be harder to get proper flow thru it and may not dissipate the heat as readily.

I am just an amateur shade tree mechanic and could be off base on this. Hopefully an expert will chime in.

 

[Quest]

TimVipond got it right! (thx!)

yes, replace the faulty thermostat with a brand-spanking new one (for domestics, it really doesn't matter if you go with Stant or Robertshaw or OE GM replacements, so long as the temperature is correct).

2nd, flush the cooling system to ensure you do not have any blockage and then refill with quality antifreeze coolant.

3rd, make sure you do not have any airpockets inside your cooling system (there should be a purging instructions in your library or elsewhere on the internet for your caprice).

 

[demarpaint]

Thanks

The Thermostat was changed about 3 years ago with the water pump, they are easy enough to do. I will try that first. What confused me was the temp guage still reads the same as it did when the heat was working.

Looks like tomorrows project.

Thanks again!
Frank D

 

[alreadygone]

Gauge or light? If gauge, does it ever get up to normal operating zone? Is radiator full? Cap in good working order without corrosion or torn seals? Sometimes low on coolant will continue to run without overheating (especially in winter)but won't supply hot water to heater. Is there a water flow controll valve in heater hose under hood? If so, can you watch it open/close as an assistant moves temp selector from hot to cool? If no controll valve, can you hear doors/ductwork open and close as you move selector from cool to hot? MANY items to trouble shoot, but simple thermostat and cap change certainly won't hurt as a starting point.

Bob

 

[AcuraTech]

Good advice by those that have posted allready. Generally when a car does not blow hot air out of the vents it means a couple of things.

1. Thermostat is stuck open slightly.

2. Coolant level is low or there is air in the system. Both usually go hand in hand and indicate a leak somewhere in the system.

3. Heater core blockage. Possibility, but the first two are much more likely.

 

[demarpaint]

Quote:

---

Gauge or light? If gauge, does it ever get up to normal operating zone? Is radiator full? Cap in good working order without corrosion or torn seals? Sometimes low on coolant will continue to run without overheating (especially in winter)but won't supply hot water to heater. Is there a water flow controll valve in heater hose under hood? If so, can you watch it open/close as an assistant moves temp selector from hot to cool? If no controll valve, can you hear doors/ductwork open and close as you move selector from cool to hot? MANY items to trouble shoot, but simple thermostat and cap change certainly won't hurt as a starting point.

Bob

---

The car has a factory temp guage. It gets to the normal operating zone after about 20 miles of highway driving. Once at "normal" temp its still blowing luke warm air from the heater.

Thanks
Frank D

 

[demarpaint]

Coolant is full and in good condition, cap is good belts hoses are good, and I can hear the flap move when going from the blue to red zone, and changing from vent, to floor to defrost.

Frank D

 

[AcuraTech]

I would replace that thermostat. Get an OEM version. I always had problems with aftermarket when I used to have a Taurus.

Besides, its a thermostat. OEM costs what, like 5 dollars more, maybe? Worth it IMO. Compare an OEM to aftermarket sometime. If the aftermarket has 2 spring coils and the OEM has 5, then you know which one is better.

 

[demarpaint]

That's what I thought, just wanted to check with the pros. I'll be doing it outside in 18* weather and want to do it once if possible.

Thanks

 

[9c1]

Your Caprice has a reverse flow cooling system -- that is the cooler fluid from the radiator goes to the top of the engine, the opposite of most cars. GM put sealing tabs -- similar to Bars Leak -- in the cars when new. This and other accumulated debris tends to clog a flow restricter that GM installed in the heater lines (a black plastic tube with an arrow on it).
It is quite common for these cars to plug at that flow restricter. Drain the cooling system and disconnect both heater hoses -- one at the water pump connection and the other at the T-connection near the coolant reservoir. Use a garden hose to flush the heater hoses and heater core both directions several times. Then flush the rest of the system.
On refilling the system you will find it difficult to get the trapped air out. One has to bleed the air out as much as possible from the bleeder screw on the thermostat housing. Be careful to minimize the coolant you get on the distributor. It is located behind and below the water pump and coolant from the bleed valve will drip on it unless you place a shop towel under the thermostat housing. One will then need to operate the car through several heating and cooling cycles to get the remainder of the trapped air out. This can take several days.
Why not join the Impala and Caprice owners over on www.impalassforum.com? You will find a lot of folks who are knowledgeable about 1994-1996 B and D bodied GM cars over there.

 

[brianl703]

Had a similar problem with a 1991 Ford Escort..it turned out that there was something (probably a pencil or a pen that fell in the vent) jammed in the blend door, which got un-jammed when I switched it from hot to cold and vice-vers several times quickly.

 

[demarpaint]

Thanks Terry, I just replaced the theromstat, and the heat is still not working, will now flush out the heater core and work from there as you mentioned.



Frank D

 

[demarpaint]

Ran out to try the flush, and forgot to post the above post. Problem solved I flushed out the heater core.

I opened the bleeder and refilled the system until I saw a steady stream. Anything else I need to do?

Thanks again!
Frank D

 

[9c1]

So long as you added the requisite quantity of coolant to keep it from freezing you are good to go. Over the next couple of days check the coolant level in the reservoir -- coolant level should be at the seam around the reservoir -- the coolant level will likely go down as some more air comes out of the system.
Check out that web forum I gave you. I have two 1995 Caprice former police cars. They are great driving cars. Just a few idiosyncracies, like the reverse flow cooling system, to keep one on ones toes.

 

[demarpaint]

Thanks Terry, will check that site out!

Frank D