Heat Problem, Please help me!!!

[nedelinkata]

Hi, I have a 2001 Gmc Jimmy and my heat does not work. The temp. is at 200 and it blows hot air for only 20-30 sec, then it goes back to cold. My engine temperature goes up at that time and then it goes down. What could be the problem?

[DJDAudio]

This would be good info for a potential buyer to know.

[nedelinkata]

no, dude I will fix it before selling
I take care of my truck
I just want to know if it is something small or not

[DJDAudio]

Its cool man,

Just pulling your chain,

My jimmy had the same problem,

I would flush your cooling system. Clogged heater core will cause this problem as well.

Is the temperature gauge steady?

[nedelinkata]

not when I turn the heat on...

[DJDAudio]

Does the temp gauge drop? when you put the heat on?

[nedelinkata]

no, it goes up for 30 sec, and right when the cold air start blowing again it goes back to normal
very weird

[DJDAudio]

Hmm the temperature gauge should remain normal as in never change.

The gauge will go past 210 the thermostat will open and it will drop back to just left of that line. and stay there.

Cheap first step is to replace the thermostat and check coolant level.

[nedelinkata]

ok...will try that tomorrow... what if it is not that???

[nedelinkata]

tststs...low on cooland