Hey guys I'm having trouble with my heater blowing cold air sometimes. It will blow hot air and then randomly blow cold air. This happened not to long ago but when it did it my car started over heating, so I put some more coolant in it and burped the system. I'm not sure what is going on now though or where to start troubleshooting. I haven't found any coolant leaks, but I'm not counting that out either.:shrug

i'd also watch for signs of a blown head gasket. Not saying that anything you said makes me think theres a high chance there it is a blown head gasket, I'm jsut sayin watch. Whenever something wierd starts to happen with coolant and engine temps i always watch for signs of a blown head gasket.

How old is your thermostat?

Were you or had in the last 24 hours raced/beat on the car when this happened?

try these:

flush/fill your coolant system
check ur heater hoses
thermostat may be opening up before its supposed to

I was thinking it could be the thermostat since i don't believe I replaced it when i rebuilt the motor about 6k miles ago. However when I put coolant in the tank and I check it again sometime later there isn't any in there. I'm not real sure what is going on there.

looks like you have some work to do then. report back w/ results.

Originally posted by 420agreenvilleSC
looks like you have some work to do then. report back w/ results.

So check the stat, check the lines for leaking or any damage, and if worst comes to worse take the head off?

just start small, isolate the problem. removing the head isn't necessary unless you torqued ur headbolts w/ no sequence and random torque loads

Originally posted by 420agreenvilleSC
just start small, isolate the problem. removing the head isn't necessary unless you torqued ur headbolts w/ no sequence and random torque loads

I put the head on doing everything correct so that wouldn't be a cause. But i'll start troubleshooting everything else and get back to you.

Usually with a blown HG, you have no heat at an idle or low range. I bet its a tstat, or a plugged heater core.

Originally posted by eclipse982nrRST
Usually with a blown HG, you have no heat at an idle or low range. I bet its a tstat, or a plugged heater core.

I thought maybe it could be something wrong with the heater core but i couldn't find any information on it.

Originally posted by thormx353

Originally posted by eclipse982nrRST Usually with a blown HG, you have no heat at an idle or low range. I bet its a tstat, or a plugged heater core.

I thought maybe it could be something wrong with the heater core but i couldn't find any information on it.

Try pulling both heater core hoses and flushing the shit out of it with a garden hose. Also, before you do that, let the car get hot by driving it for awhile, come back, let it idle, and feel both heater core hoses...see if both of them are equally hot to each other.

i hate the damn heater core hose connections. an absolute bitch to get to while the engine is in...

Run the engine for 10 minutes with the radiator cap off, and he heater on full blast. That should get any air bubbles out of the system. If the coolant level drops while you are doing this, just keep adding more.