Overheating when idling with A/C on

Tiny
MRBLAZIER
  • MEMBER
  • 2001 CHEVROLET TAHOE
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 169,000 MILES
My Tahoe starts to overheat when idling with the a/c on, but its fine when the a/c is off or while driving. When idling with a/c on and it starts to overheat I can rev the engine to 1000 rpm or more and it will cool back down. I have replaced the thermostat and coolant but still no luck. HELP!
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Thursday, August 7th, 2014 AT 10:15 PM

10 Replies

Tiny
WRENCHTECH
  • EXPERT
First, make sure the coolant is remaining full and pressure test the system if it is losing any.

If no coolant loss, I would suspect and issue with the fan clutch.
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Friday, August 8th, 2014 AT 2:41 AM
Tiny
MRBLAZIER
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Replaced fan clutch dident help. No coolant leaks either
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Monday, August 18th, 2014 AT 5:12 PM
Tiny
WRENCHTECH
  • EXPERT
How hot is it actually getting?
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Monday, August 18th, 2014 AT 5:15 PM
Tiny
MRBLAZIER
  • MEMBER
The gauge usually is right in the middle but I, ve only let it go to the 3/4 mark which I believe is 235
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Monday, August 18th, 2014 AT 5:21 PM
Tiny
WRENCHTECH
  • EXPERT
No, 3/4 won't be that hot. 235 would be in the red.

If it only overheats at idle, it has to be either an issue with the fan or possibly the water pump but that would be rare.
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Monday, August 18th, 2014 AT 5:26 PM
Tiny
MRBLAZIER
  • MEMBER
Well in the middle is 210 and the gauge only goes up to 260. Since I've already replaced the fan clutch and the fan is in good condition guess I have to replace the water pump.
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Monday, August 18th, 2014 AT 5:32 PM
Tiny
WRENCHTECH
  • EXPERT
We generally do some testing before throwing parts at it. There are way to determine if you are getting circulation.
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Monday, August 18th, 2014 AT 5:37 PM
Tiny
MRBLAZIER
  • MEMBER
How do I test for proper circulation? What other testing do I need to do?
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Monday, August 18th, 2014 AT 5:42 PM
Tiny
WRENCHTECH
  • EXPERT
Sometimes you can see into the radiator cap and see irt flowing out of the tubes or you can rig up some type of clear section for the radiator hose.
You can disconnect the upper hose and run the engine to see it flow but you have to keep the radiator full and the cold water will tend to close the T-stat.
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Monday, August 18th, 2014 AT 5:47 PM
Tiny
MRBLAZIER
  • MEMBER
Ok will try that.
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Monday, August 18th, 2014 AT 5:49 PM

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