This just started tonight! I have a 2000 chevy tahoe 5.3 v-8 new body style. I noticed my heater does not work as well as it did before and when I am a stand still heater starts to blow cold air. Any ideas what that could be? I drove around after i noticed it and it kinda worked better but not to what it supposed to be! Any ideas or suggestions would be great!

 

It could be something as simple as being low on anti-freeze or a faulty thermostat or radiator cap or a bad control unit or diverter door mechanism.

 

I am having the same problem with my 2000 Tahoe, new body. The day that I had the cabin air filters changed during lube service, the heater began blowing cold air even after the engine temp was up. This continues until at some later point, it just gets warm accompanied by a hot smell. The system then functions normally. It could just be a coincidence that this began the same day that the cabin air filters were changed, but the filters had not been changed in ten years! I didn't even know that they were there.

I was hoping to get some ideas on the Forum. I'm leaning towards getting the coolant system flushed. There are little screens on the heater core lines that can become clogged requiring reverse flushing.

 

Reserve tank was empty the other day so I filled to line with green 50/50 water antifreeze
didnt know there was a special kind for chevys. Heater started blowing cold today. Can't flush or buy the proper antifreeze till Friday.

is it all gonna jack up my radiator?? 😭

 

Welcome to the forum.

From what I've heard over the years since GM started using the pink/orange antifreeze, mixing that with the old green antifreeze would cause the coolant to gel. If that's true, then you probably would have to get the heater core and radiator flushed. If that's not possible then you will have to replace both of them.

 

Did you notice if on the jug of the green antifreeze you used, if it said can be mixed with Dexcool? If it did than you should be ok. You may have a partially clogged heater core. When mine was clogged, reverse flushing didn't help. I had to use my air compressor to blow it out.