2009 PT Cruiser overheats only if the defroster is off… checked the water pump, replaced radiator cap, thinking it could be thermostat…what are your thoughts?
Did you check if the electric radiator fan(s) function?
Tester
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Definitely sounds like the fan isn’t responding to high engine temperature. When your defroster is on, the A/C is on, and that has a separate trigger for the fan, regardless of engine temperature.
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