hvac fan causes engine to stumble

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Jul 23, 2006 | 06:26 PM

'89 Iroc

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Joined: Jun 2006

Posts: 41

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hvac fan causes engine to stumble

Recently when i turn my fan on high my engine will start missing but it only does it on high. any ideas?

Jul 23, 2006 | 09:43 PM

rgarcia63

Supreme Member

Joined: Jan 2003

Posts: 2,133

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From: Houston, Texas

Car: 88' IROCZ

Engine: 388 TPI Motown 350 Race block

Transmission: 700R4

Axle/Gears: 2.77

Quote:

Originally Posted by '89 Iroc

Recently when i turn my fan on high my engine will start missing but it only does it on high. any ideas?

ECM is programmed to increase the fuel supply to compensated for the extra load from the A/C (also seen as a voltage drop.)
ANy thing that depends on the voltage being 12v, or regulated 5v will be affected although the ECM tries to compensate, might test your battery and alternator even if they're fairly new.