# 2002 Chevy S10 Pickup Heater Control Vacume Leak



## myanchar (Nov 10, 2008)

I have a 2002 Chevy S10 pick up ZR2. 4.3 L automatic with air and heated mirrors. The problem is i hear a vacume leak at the heater controls, on/off temperature control. The leak seems to go away when I accelerate and then comes back as I coast. The real problem is that the heat stays at the vents, it will not go to defrost or go to heat by your feet. I replaced the complete control assembly from a junk yard and it went away for awhile, maybe 3 months. I'm not sure if it really went away or not as I was not driving this vehicle much during this time. Also it was summer then. Before I invest in another control I wanted to make sure it wasn't because of lack of vacume, the truck has 170,000 miles on it.


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## octaneman (May 13, 2009)

Hi myanchar


Internal vacuum leaks can only come from the vacuum actuators, what you will need to do is open the bottom panels and attempt to isolate where the vacuum leak is coming from. While your checking for leaks, play with the knobs and switches on the control assembly and see if the cables or vent tubes are kinked or disconnected. Focus on the air box, pay close attention to the trap doors opening/closing while listening for leaks. 



post back your findings.


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## Raylo (Feb 12, 2006)

On my older S10 4.3 (1994) the vacuum line for the HVAC system came in through the firewall up near/behind the distributor. It was connected to a tee back there. That line can get brittle, then crack and leak... or just get bumped and disconnected. Maybe worth a quick look if you don't find anything inside.


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## kjms1 (Jun 4, 2010)

find the vacuum leak and you will fix your A/C heater problem


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## myanchar (Nov 10, 2008)

Yes, but it sounds like it is coming from the controls. Is this model known to have a problem with the control leaking vacuum. There are about 5 vacuum hoses going to the selection switch, the one that controls if it's defrost, vent, foot, and air. It sounds like this is where the vacuum noise is coming from.
Thx,
Mike


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## octaneman (May 13, 2009)

Use silicon spray or sealer where the hoses and coupler meet that go to the selector switch and see if it makes a difference. Sometimes the far side of the coupler where the hoses are inserted becomes dry creating a gap.


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## kjms1 (Jun 4, 2010)

*I replaced the complete control assembly from a junk yard* 
that was your first mistake 

if you got a spare piece of hose place it to your ear and move the other end around the control unit when the hose is right in line with the vacuum leak you will hear it for sure extremely loud


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## schimmy (Apr 19, 2011)

Myanchar- I have the same exact problem and I have a 2002 Chevy S10 LS crew cab. Were you able to resolve the issue?


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