1999 Other Saturn Models Heater blows cold air

HEATHERG0170

MEMBER
1999 SATURN

Heater problem
1999 Other Saturn Models 4 cyl Wheel Drive Type unknown Manual 100, 00 miles

The heater in my car has been progressively getting worse where it used to heat great to now it does not heat at all. The air blows fine in all settings, the temp. Gauge indicates the car in heating but no hot air. I also noticed that my rear window is suddenly not defrosting either (not sure if related). Should I just replace the thermostat or bring it in for a more thorough look?

2 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Ry warming the Vehicle, then carefully feel the heater hoses, are they both hot? If one is cooler than the other, You need to flush the core, or do a replacement job on the heater core. Also if the system has a heat control valve on the heater hose, make sure it is working! Also check the thermostat, and the temperature blend door, thats under the dash, in the heater plenum. You can flush this yourself, buy the prestone flush kit and install the tee in the heater return line. Disconnect the heater hose at the waterpump, clamp the hose in back of the tee you installed and back flush till it runs clear.20 mins or so.
Thermostat could be weak as well.

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Monday, January 14th, 2008 AT 11:56 AM

PHOENYIX

MEMBER
13 POSTS

If you're not comfortable working on it yourself take it in but here is a few things to look at first. I'm not sure what model you have so I'm guessing a little here. First check the temp gauge to see just how warm the engine is getting, it should get to at least the 1/4 line. If not the thermostat may be bad. Second move the temp knob from cold to hot and see if it moves way too freely if so the cable between the switch and the flap to adjust how much heat is let in may have broken or come off. Third after the car has warmed up pop the hood and feel the hoses going to the heater core (near firewall) feel if the hoses are getting warm, if one is warm and the other is not you may have a blocked heater core, if both are warm then heat is getting into the car and that could indicate that the flap isn't working.

The rear window is totally separate. You may have a bad grid (the little copper lines on the window) or the electricity isn't getting to the grid itself an ohm meter can tell you that.

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Monday, January 14th, 2008 AT 12:11 PM