Heater Core Question?

[wma4553]

1999 Tahoe. Is water supposed to be circulating through the heater core when the AC is on?

 

[JenneK]

Yeah. Depends on what the temp is set at though. There is a shut valve on the heater hoses that will prevent hot coolant from circulating through the core if heat isn't called for. That valve could be defective and still allow coolant to flow through. If so, the cooling performance is reduced.

What's goin on with yours?

 

[wma4553]

Mine circulates all the time, I replaced the valve you mentioned but no change. The valve is vacuum operated so I think that may be my problem because the rubber hose has some vacuum but it dosen't seem like enough to close the valve. May be a problem with whatever controls the vacuum to the hose. The hose looks good but I guess it could be clogged internally.

 

[SunlitComet]

there is a solenoid on top and right of engine that controls the vacuum for it. follow the hose.

 

[wma4553]

I decided to quit throwing parts and money at it and put a $15.00 manual shut off valve on it. Someone told me that it is supposed to always circulate through the core so you can mix a little warm air with the AC if you get too cold (I never do, I live in Mississippi). It seems a little counter-productive to have that hot box sitting next to the AC coils, hopefully my AC will get a little colder now.

 

[_Dylan_]

A/C working better?

I think mine might be doing the same thing. My A/C isn't very cold and I occasionally hear a gurgling sound with the A/C on. I think its coming from the heater core.

 

[SunlitComet]

if it is high pitched hissing gurgling then that is a/c and generally normal but you could still have the wrong charge tho. a pouring water gurgle sound is air in the heater core.

 

[_Dylan_]

Yeah it makes a hissing sound too. I think I have a pressure gauge somewhere...