Heater blowing warm air then cold air

[maxim1157]

Last night I had stopped at a friends house and left my car running, when I came out car was overheated. I let it cool off and added some water to get it home. I found that the 20amp fuse blew for the fan. It threw out coolant when it overheated, I refilled the coolant tank and made sure that the fan was working. This morning driving into work I noticed that it was kinda warm air blowing from heater, when I turned fan on high it started to cool down and blow cold air, then a few minutes it would heat up and blow warm air again. Is it possible that it's just air in the system from losing coolant and then adding again?

[Thud Slamrod]

Its possible, you'll have to let the car sit and run with the cap off of the tank and the heat on until coolant starts circulating through the radiator to work all of the air out of the system.

[xintersecty]

It's very very possible your T-stat died. I would replace that and make you sure you have a metal housing.

[petrified.rabbit]

It's very very possible your T-stat died. I would replace that and make you sure you have a metal housing.

i agree.. your issue is not that you replaced the coolant, it is that it overheated in the first place.

[maxim1157]

I replaced the thermostat last fall before winter set in..
I tried leaving the cap off while running the engine to circulate the coolant and get the air from the system, this seemed to work but now I have an issue with the coolant boiling out of the overflow tank if I bring the coolant up to the middle of the tank. Looking closely at the cap it looks like it has a crack almost 75% around it ..hoping it's the cap and not the head gasket from overheating it.