My Heater Blows Cold Air...WTH?????????
 

2000 Silverado Reg Cab V6 blows cold air when temp control is set to hot. The beauty is I am staying cool in the 90 degree Oklahoma Heat, but one day it will be cold outside and need some toasties.

What do I replace? Help a brother troubleshoot. I just bought this truck from a used car dealer last Saturday and figured out this problem. I guess that's what I get for selling my 2007 Tacoma.

Any help would be much appreciated.

Is your anti-freeze filled to the proper level??:)

Clogged heater core or bypassed???

Sounds like a bypassed heater core.

What is a "bypassed" heater core. What do I do bout it?? I hear it is a biznich to replace.

A bypassed heater core is not going to blow cold air in 90 degree heat. It will blow the temp of the outside air. I would check the control head to make sure it is actually switching to heat and that the compressor is off when on heat. Do you have the "A/C" button off?

What is the best way to test the control unit? I don't hear any change when I switch from A/C to heat and back. I should hear it click on and off right?

BTW coolant is new and topped off.