You need to go to a car parts store, and get a repair manual for your car. They cost about $16.00 Or, go to a Public Library.
Detach the screw that attaches the heater duct on a Chevy Cavalier and remove the heater core. Once this is done you can replace the faulty heater core with a functional one.
Try this link it even has photos http://www.v6z24.com/howto/heatercore
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There are heater-resistance wires in the glass of the back windshield.
The Front-Passenger-Side Cylinder
Probably around $500 or more if you have AC.
Remove the water supply hose from your 1988 Chevy Cavalier thermostat housing. Remove the thermostat housing bolts. Lift the old thermostat out and drop in the new thermostat.
Here is a link with pictures, tools needed and everything to do the job. http://www.v6z24.com/howto/heatercore
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i have a 1997 chevy cavalier the wipers and radio work when turn the key swich back