Heater warm air only

[ice_it_06]

1986 Caddi Deville 4.1 liter

Heater has been pushing out only warm air. Enough to defrost the windows enough to drive, but heat is minimul and car cold below freezing.

I put in a new stat today and in the process siphoned everything out of the radiator/upper house first. (replaced with new coolant 1 1/2 gallons)

No change, nothing in the heat degree increased.

Any suggestions greatly appreciated.

I have good fan, all ducts working, hoses good and hard, temp will drop to cool on the electronic cooling system these things have, but only to "warm" on the upside.

No signs of a leaking core, heater lines on fire wall/corner are impossible to reach as I was thinking of a flush.

** any thermostat I have previously replaced I found coolant under the stat in the block. This one was dry under neath and nothing but clean aluminum block was seen.** Car has 52,000 on it.

[Cliff Wagenbach]

You replaced the thermostat so I would have to guess that your heater core is plugged.Or you got a bad new thermostat!

Cliff

[ice_it_06]

Cliff:

I think it is something other then the stat. The OEM I took out looked in good shape,not gummed up or anything and good spring.

The new one is definitely a "cheapo" as the OEM looks heavy duty compared to the NAPA stat I got. Probably give GM their $20 I guess for another OEM.

Maybe I can cut the hoses leading to the core farther up line of it's connection and try to flush it out and reconnect with some hose connectors.

Time to get under the dash I guess and start tearing things up if that fails.

[HaywardBound]

I had the same problem with an '89 Deville. Replaced stat, flushed, did not help. I never did find the problem, but someone at GM said it could be a costly repair? Mine had something to do with the climate control.

Sorry I can't help, but let us know what you find out.

[ripstick]

Who knows who made GM OEM they change all the time. When is the last time you had it completley flushed. I would try that. Might be able to tell if core is pluged.

[Scott K]

I would check to see if the heater hoses that go into the car are hot, and if the return from the heater core is hot.

Heater core could be plugged, water pump impellars fall apart. If the car is heating good, check the vacuum valve on the heater hose for the heater core.

[Down2Earth]

here is what I have done on two of my vehicles in the past with this same problem. From underneath the car disconnect the 2 hoses going into the core. (Be careful not to grip the hose to tight on the end because you don't want to deform where the hoses are connected) Then take a garden hose and flush it with water for a good 5 minutes to flush out the core. Hook the hoses back up and you will have heat pumping again.

[upnorth]

This was a ways back, but we had a 1980 Park Avenue with the same issue. Sorry to say it wound up being the electronic climate control system. I found one at the junk yard pretty reasonable, new was dang pricey.

You may have something plugged, but don't rule out the climate control.

[BIG DS]

Could be the climate control, blend door issue, heater control valve under the hood. The blend door is what controls the heat in the vehicle. If it is stuck or the actuater is dead, it may be letting cool air in along with your heated air leaving you with luke warm air. If so, you will end up with someone taking out the HVAC box to repair it. Good luck with it.

[ice_it_06]

I have a "87" duplicate car sitting 30 feet from the one with issues. It's a parts car so if it's the electronic control I pull that one out.

Will attack the matter after Christmas, don't want to ruin my holiday over this car or interfear with my fishing. I'll forward what I find out, gonna store it for the winter anyway.

Appreciate all the advise believe me