2001 Chevy Blazer heater core / thermostate

Tiny
ZIGGY61
  • MEMBER
  • 2001 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 86,500 MILES
I replaced the thermostate on sunday. Had heat yesterday. Today no heat. Could the core need flushing or the heater control valve be stuck? I have no leaks nor is there a smell of coolant.
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Tuesday, February 16th, 2010 AT 1:47 PM

4 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Try this test. With the engine on, hot, and the heater on high, are both heater core hoses hot? Also, is the engine running at a normal operating temo?

Let me know.
Joe
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Wednesday, February 17th, 2010 AT 10:06 AM
Tiny
ZIGGY61
  • MEMBER
Both hoses were hot. One more so than the other, I think the outbound side ( left ). The engine temp is running normal as well.

Today I let it run for 20 min prior to your suggestion & there was heat.
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Thursday, February 18th, 2010 AT 5:50 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
THe reason I aske that you do that was to determine if the heater core is plugged. If both hoses were hot, it isn't. That is a good thing.

WHat is left is the blend door. It is located near the heater core. Its job is to do the following:

WHen you want heat, closes on one direction to force the fan to blow over the (hot) heater core. When you want AC, closes the other direction to block the heat and allow AC to enter. If it isn't closing fully, it will block all or some of the air going to the heater core. As a result, you don't get much heat if any at all. Again, the heater core is good; therefore, the blend door must not be working properly.

Have that checked and let me know what you find.

Joe
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Thursday, February 18th, 2010 AT 7:43 PM
Tiny
ZIGGY61
  • MEMBER
The blend door works fine as well. I still get warm to moderate hot air one day andcold the next. I'm going with the heatercore is somewhat blocked.
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Monday, March 1st, 2010 AT 9:27 PM

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