I think it overheated due to being low on coolant. Just a guess. And pissibly the thermostat was bad. So I replaced that. It is still blowing cold air out of the vents. The waterpump is not leaking, nor is the heatercore. I am trying to fix this myself, being a singlefemale I dont know what else it is. Help!!!!

 

I would assume you topped it off from being low? Is it still overheating? i would look at a clogged heater core or a bad water pump. I would guess more towards a clogged heater core....

 

Yes, i topped it off and it is not overheating. I let it idle in the garage for roughly 1/2 hr . Holding the gas at 2500 rpms it blows out some warm air, idling at 600 rpms, back to cold.

 

In that case i would flush/back flush the heater core... In the past, i personally pulled both hoses off at the front of the engine and plugged one end and put a funnel on the other... then i filled the heater core with CLR and let it sit for like a half hr. next i hooked it up to the garden hose and flushed it with fresh water for a good 20 mins.

Keep in mind if you have a failing heater core putting any type of chemical into it could cause it to finish it to full failure.

 

i would venture a guess you have an air bubble stuck in the heater core, but anything restricting flow could cause this

 

Which engine?

I have a 4.7L that started with an overheat and no cold air. I topped off the coolant, would run the truck.....let it cool for a day and open the radiator cap and there would be no coolant in the upper hose.

That can be a symptom that there is a leak in the collant system somewhere, and when the hot coolant cools and contracts it is pulling air into the system rather than coolant from the overflow bottle.

 

I am going to try flushing it out with a garden hose tomorrow. Its the 5.2 motor. Hopefully this works and it doesn't need to go to the shop for a new heatercore. I can only imagine the cost of having that done...

 

It still could be the Water pump. I just had that issue recently. Low fluid level, blowing cold air. Refilled resevior still cold air. New thermo...no joy. Bled the system, back flushed heater core. Did the spin test on the fan for the water pump looked like it checked out within specs. But i decided if I had it apart, drained and in the shop might as well check it. Found the Impeller for the pump sitting inside the housing it had ''sheared'' off the shaft. I use that loosely becauce there were no wear marks on it. It looks to have just fallen off. Guess thats what happens when you have press on impellers.
My 2cents would be to change the H2O pump before tearing into the heater core. Less time and effort....And money if you take it into the shop