Thread: heater/ ac problem 3.8

heat worked last winter, now it doesnt. ive been told it could be a bad heater core or that i may just need to flush the system. then i also noticed my grand prix with get up past 220 temp before it cools down??

many many many things can cuase this.

Let's start simple - do you have the proper amount of coolant?

yes i do i just filled it up whith my oil change 1500 miles ago

Is the system bled? Air in your coolant will cause temp spikes.

If it's bled, turn on your heater (with the car warmed up), pop the hood, and feel your heater hoses. If they're hot and firm but your heater is not working, then you have blend door problem or a clogged heater core.

one tube was reallly hot, and the other was just warm, possibly from the engine heat. when the heat is on i also hear the air being sucked in from the vent by the windsheild washers.. is that normal for heat?

Both are normal and what you should expect.

The heater core is nothing more than a radiator in reverse - hence the reason that one tube is hot and the other one warm. The heat lost is that lost in the core itself (transferred to the air across its fins).

It sounds to me like your blend door is the problem. The blend door is a door that mixes the hot/cold air in the cabin. You need to take apart your dash to fix it.

oh boy, sounds fun aha.. -_-

Also - a clogged core will cause the same issue. The supply hose will be hot and the return one warm/cool. If you engine is warm - both hoses should be hot with one slightly (very slightly) cooler than the other. If one is hot and the other one cool, then you have a clogged core.

so if they hoses are working properly, then its the blend door?

For all intents and purposes, the hoses should be about the same temperature. The return hose will be SLIGHTLY cooler than the supply hose if the core is working right. This heat is lost to ambient via the core itself.

If one hose is substantially (>10%) cooler than the other, then you have a clogged core.

If you have the OE dexcool in your system (the red coolant), it will turn to sludgee if exposed to air. So, if you have any leaks in your system and have the OE coolant, you very likely have a heater core filled with dex-sludge.

Of the two possibilities (both of which could cause your problem), the clogged core is more likely. Look at your coolant reservoir - if it's filled with globs of sludge, then so is your core.

What year is your car? How low were you on coolant? Reason I ask is that if it's a mid '05 and down then you could have leaking LIM gaskets loosing coolant and exposing the system to air as mentioned, which will turn the orange Dexcool into sludge, among other things. If you're loosing coolant all the time you need to find the reason and fix it. Leaking LIM gaskets can cause bearing failure if left alone long enough. If the system is really low and you refill it you could have air trapped in it causing a spike in temps due to air pockets. Bleeding the system via the vent on top of the thermostat housing should fix this.

If you pull the oil dipstick and see what looks like a chocolate milkshake on it, then you are eating coolant and need to fix it asap before you spin a bearing and toast the motor. If not, then look elsewhere for leaks. Worst case pay a shop to pressure test the cooling system to pinpoint the leak. Could be a few things.

the oil is fine, i just think im going to start by flushing the system and bleeding it. its a 1999 gt, 3800 non supercharged, and would u happen to know of any common ac issues

i see, well ill focus on the heat first i was just wondering.