Heat and A/C stop when accelerating?

Tiny
CARL SMILEY HINZ
  • MEMBER
  • 2013 CHEVROLET EXPRESS
  • 2.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 50,000 MILES
I have the vehicle listed above 3500 van when I accelerate the heater turns cold and when I let off the gas it works again. It did the same with the A/C.
Tuesday, May 20th, 2025 AT 6:17 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,615 POSTS
So this happens when the engine vacuum goes low under load. There is a vacuum storage tank (ball) under the hood I would make sure the vacuum lines do not have any holes/cracks. Also, the van may have a vacuum pump that is not working as well. I would turn the key on to see if the vacuum pump comes on. Also, near the vacuum storage tank there will be an inline vacuum check valve. If you remove it, you should be able to only blow through it one way, if both ways work the valve is no good. Check out the images (below). Let us know how it goes.
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Thursday, May 22nd, 2025 AT 10:45 AM

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