Dramatic loss of Power with AC on

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dubfreaks

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My 5.3 feels like a 4 cylinder when my a.c. is on, it's hot out, and the clutch fan is engaging. I've read that some notice a loss of about 10-20hp and then others notice no loss at all. Is there a common issue that can cause this and doesn't anyone know of any fix?

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M1Gunner

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My 5.3 feels like a 4 cylinder when my a.c. is on, it's hot out, and the clutch fan is engaging. I've read that some notice a loss of about 10-20hp and then others notice no loss at all. Is there a common issue that can cause this and doesn't anyone know of any fix?

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First do a quick check of your Throttle Body. It may be time for a cleaning.
 

mizzouguy

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On my 04 you can definitely "feel" when the ac clutch engages and disengages going down the road. It's noticeable but not enough to be considered abnormal. And yeah I have a severe duty fan clutch dragging things down as well. Unless the compressor is locking up, just drive it.
 

M1Gunner

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It's a pretty common thing for our 5.3's when the throttle body gets nasty, running the AC will cause it to run like junk but it seems fine when the AC is off.

It may not be in your case but I've seen guys replace compressors, thinking they were starting to lock up, even after suggesting to them to take 5 minutes and try a throttle bottle cleaning. And it biting them in the rear.

Again, just a suggestion.
 

CTUBS8732

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Did your issue ever get resolved? I'm having the same problem. Just replaced my compressorand tahoe Doesn't down shift anymore. Even with the pedal floored.
 

DJPoertsch

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I have the same problem on my 2007 Tahoe. I lose a lot of power when my compressor switches on. I have already changed new spark plugs, ignition cables and the ignition coils. As soon as the compressor is switched on it feels like it is running on 4 cylinders. But only when it turns on. Three days ago I carried out a professional air conditioning service with an extraction leak test and refilling. Could it be that the air conditioning compressor is defective?
 

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