Heating/cooling not working properly

2001 PONTIAC GRAND AM
200,000 MILES • 3.4L • 6 CYL • 2WD • AUTOMATIC
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MECHRAY
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  • 2 POSTS
The overflow is full, but driving down the Highway, the heater blows hot. Then all of a sudden it blows cold for a few minutes then it's back too hot. It happened several times. Does this mean there is air in the system, and it should be bled?
Mar 8, 2022 at 11:44 PM
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JACOBANDNICKOLAS
  • CAR REPAIR CONTRIBUTOR
  • 110,190 POSTS
Hi,

If the system works on and off and the coolant is full, it's likely an issue with the blend air door. However, when the engine is cold, you may want to confirm the radiator is full.

Next, if the system hasn't been opened, there shouldn't be air in it. Has anything been done recently to the cooling system?

If not, have you ever noticed a clicking sound from under the dash? If so, that is likely related to the blend air door. The actuator has a small plastic gear in it that is known to fail.

Under the dash on the passenger side, locate the actuator. See if anything is loose at the connection or if there is any evident damage to the wiring or connector pins.

Let me know.

Joe

See pic below.
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Mar 9, 2022 at 3:00 PM
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MECHRAY
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Possibly. I take a looksey. FYI, only cooling system work was a water pump 6 months ago and he did bleed the system at that time.
Mar 9, 2022 at 3:09 PM
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JACOBANDNICKOLAS
  • CAR REPAIR CONTRIBUTOR
  • 110,190 POSTS
Hi,

Sounds good. Let me know what you find or if you have other questions.

Take care,

Joe
Mar 9, 2022 at 4:14 PM
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