Heater Cores and Blower Fans
Car Heaters
1982-1994 Chevy Cavaliers

What causes a heater to blow hot air as soon as you turn it on but then to blow cold air?

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Answer

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Wiki User
05/28/2011

If the car is setting in the sun.Heat builds up in the ducts.

With my car, it was Heater matrix clogged with radiator sealant. The workshop cleaned it and it's start working fine!