CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

1999 Chevrolet S-10 - Cold heat

Heater dont biow hpt air

There are a couple of possibilities. Does the temperature gauge show in the normal range? If not, the thermostat could be bad. Have you checked the coolant level? There could be air in the heater core. Or the heater valve could be bad or stuck. You need someone with hands on to do a proper diagnosis.

speaking from experience . . .

If the coolant level is correct and the engine’s reaching proper operating temperature . . . most likely the heater core is plugged

If this is in fact the case . . . you verify this by getting the engine up to proper operating temperature and feeling both heater hoses with your bare hands; one will be hot, whereas the other will be much cooler to the touch . . . you can often improve or even fix the situation by flushing out the heater core with a hose. A lot of crud will probably shoot out, so be aware, and have a tub underneath the truck, ready to catch any crud and/or coolant

1 Like

When my car would not blow hot air last winter, I first removed and dismantled the heater water valve. Looked fine inside. Then I blew through the hoses and found the heater core was plugged up.
I disconnected all the hoses so I was flushing the heater core independently of the rest of the cooling system so I would not have to worry about having corrosive chemicals all through the engine.
Tried Prestone flush and boiling hot water. I forced a little through but did not clear the problem. Then I tried IronTite Flush. That is serious stuff. Don’t leave it in more than 10 minutes and flush it out thoroughly. It worked great.

1 Like