Temp Control Valve

[BillWms01]

My '00 Yukon XL's front air conditioning is not as cool as it should be.  The A/C is working fine (rear blows real cold), so I suspect the temperature control valve that lets hot water circulate through the HVAC is not shutting off completely.  As a matter of fact, it tried to stick once, and not cut the water off at all.

 

Can someone give me some guidance as to how to get to the valve?  I've pulled some of the lower dash cover, but can't see the valve.  I can hear the servo motor running when you turn the dial.

 

TIA

 

BillWms01

[toddgotfish]

Bill

i'm looking at the haynes manual and i don't see a valve to cut off the water flow at all to the heater core

and after i ran my a/c today i got out to check those heater core lines(hot as all get out)

i think they simply use a damper to float between the heat core and a/c coil which as far as i know is adjustable

hope this helps

Todd  :thumb:

[BillWms01]

That's interesting...

 

I'll look around and see if I can see a damper actuator, instead of a water valve actuator.

 

Thanks.

[BillWms01]

Todd,

 

Man, I've got to get me a Haynes manual!  You were exactly right.  There's a servo actuator that moves the damper just as you described.  This morning, I removed the black plastic cover at the bottom of the HVAC unit (what you feet hit), and there's the actuator.  Very easy to get to.  I pulled it and stroked it back and forth, and then it just quit (on the heat end of the stroke).  Wouldn't budge any more with moving the dial from hot to cold (red to blue!).  It did this the other day also, letting super-hot air come out the vents.  After awhile then, it finally went back to only "warm".  

 

I pulled the actuator off the unit, and without it, there appears to be no hot air bypass.  So, it's either the actuator or the dial on the dash (would that be a potentiometer?).  I'll try replacing the actuator first, I guess.

 

Thanks for you help, and hopefully this thread will help someone else in the future.

 

BillWms01