heater issue and overheating

[pathology knight]

a while back my heater only worked for about 30-45 minutes, and then would start blowing cold air (probably from outside (not "a/c" air)).

a couple weeks back, while driving for about 45 minutes with the heater controls on, the car overheated. i pulled over for a few minutes to let it cool, added some water to the bottle, and drove off with the heater OFF. the temp was back to normal. it drove fine for a few days with the heater off.

i haven't driven it since. obviously something is up. any ideas?
i was thinking maybe the heater core needs replaced? the coolant system was flushed just before the winter, but i think it might need it again. they didn't do a very good job, and the fluid in the bottle (that i can see) is gunked up and brown again.

[FIREBIRDV6RAGE]

Re: heater issue and overheating

when you use your heater does you coolant level go down?

[2.8 Bird]

Re: heater issue and overheating

I'm guessing your core may need to be changed.

I think our cars came with a horrible core, but I would try flushing and changing the fluid first and see what happens.

[pathology knight]

Re: heater issue and overheating

with the heater on, i don't notice anything with the coolant level.

of course, i don't really know how to check it. i don't think there's a gauge for it... is there? (if there is, i'm going to sound like an idiot (again)).

[Docta]

Re: heater issue and overheating

Grab a water hose, like to water your grass, seal it up to the heater core lines, turn it on high, see what comes out the other end. Just make sure both ends are disconnected. If it's just clogged, that'll have more pressure than your engine to push some **** out.

[GaryDoug]

Re: heater issue and overheating

The heater being on had nothing to do with the overheating. It was most likely a low coolant level that caused both symptoms. There are no valves that control coolant flow to the heater core; the coolant is normally flowing through the heater core at all times. Only the fan and vent valves are controlled by the HVAC control panel. I have my heater core flow blocked most of the year with a manual cutoff valve and experience no overheating issues. Learn how to read the coolant level in the reservoir like normal, and to read the coolant level in the radiator (when the engine is cold). It is always possible the level in the system is low and the reservoir is ok because of a defective radiator cap or plugged hose to the reservoir, so I recommend checking both levels occasionally.

And btw, make sure the coolant is a good mix of antifreeze/summer coolant and water (maybe 50% each) or you will get frequent boil-overs and coolant loss.

[FIREBIRDV6RAGE]

Re: heater issue and overheating

i would just buy some coolant flush and read the instructions on the back and follow them. after that's done flush it just with water while the car is running and have the butter fly screw open from the radiator, as the car is running water will go out and fill the radiator as needed, do this until you see water as clear as the water you put in . this is the way i did it.(mine had a bunch of gunk) then get some new coolant and put the right amount in as suggested from gm. then mix its with water , make sure its a 50/50 mix just as garydough said. after all that is done i would let the car warm up to a normal tempature . and bleed the system from any air trapped in it. the way you do this is just open the screw from the thermostat housing and let it stay open until only coolant comes out then close it. and your done. after that see if you still over heat