Grand Am Heater Problems

[Huskie]

I have a 2001 Grand Am. I will be driving along with the heater working fine, and then the heater will start blowing out cold air all of a sudden or if i change the fan speed it will blow cold air. Sometimes the heat will come back on its own, however, usually after I turn the heat knob down to cold and back up to hot it will come back on or if I turn the fan off and then back on it will heat again. Could this be a wiring problem? Or a heating core problem? Any ideas would be greatly appreciated. Thanks in advance.

[Macgyver55]

What engine and how many miles? This sounds like it could be a low coolant problem. Check the level of the radiator, not the coolant reservoir. Make sure the engine is cool when you do it and if it is low, refill it. There is a bleeding procedure you have to do to get any trapped air out of the system. Once you do that and warm it up, you should have heat.

Now, assuming it was low....now you may have a new problem....where did it go? A pressure test will quickly tell you if it is an internal or external leak. This time of year with cool mornings its common for hoses and clamps to leak, so hope for that, because if its internal its more likely an intake manifold gasket. The 3.1 V6 motors are fairly common for leaky intake gaskets.

[Jeremy airjer W]

That year came with a 2.4 liter 4 cylinder or a 3.4 liter 6 cylinder. The 3.4 Is also prone to the famous GM intake gasket problems but throws in another interesting twist. We have found this motor to have head gasket failures in a lot of the GM minivans for some reason. I don't recall seing this in a passenger car yet but would not rule it out.

if it is a 3.4 and the coolant is low, which it more than likely is. Take a peak around the area under the trottler body where the trans and the motor bolt together. Trails or puddles of coolant will probably be visible. If so the intake gasket has gone bad! if its severe enough it will start to leak coolant into the oil. Pull of the oil cap and check for a chocolate milk looking substance covering everything. If the oil on the dipstick looks the same then you may have some bigger problems. These motors and especially the 3.1's do not like any coolant in the oil for any length of time.

[Huskie]

It is the V6, dipstick looked fine when we checked the oil, will take a look at the cap next. That model doesn't have a cap on the radiator, unless it has been changed out, only on the overflow resevoir. I did add a little to that as well. Toward the end of the summer the air conditioning went out also, wondering if it was a Katrina car or just need work, has 76000 miles.

[Macgyver55]

What you describe with your heater is one of the classic symptoms of a low coolant problem. So, assuming that it is low, adding to the reservoir alone isn't enough on these engines. It MUST be bled to remove all trapped air in the system. As you are looking at the engine, on your left side (towards the front) of the engine there is a black tube that stands in a verticle position. It has a small brass screw in the top of it and a heater hose coming out of the side of the tube. This screw needs to be opened until only coolant comes out. I usually run the the car with the heater on and open the screw a few times after it is warm to assure it is completely purged of air. There may be another bleeder at the thermostat housing where you can also bleed. If there is, bleed at both places. If there is air in the system this should correct the heater problem but you still need to find out where the coolant went.

[slick814]

If it isn't a low coolant problem, you may have the problem I had with an older Grand Am.

The heater core had some gunk in it, and needed to be blown out to remove the sludge (for lack of better term). You may also want to flush & fill the radiator, as it might be something in the cooling system.

Possibly a stick thermostat could cause the problem too, if it sticks wide open and then closes again.

[BIG DS]

Well, check the coolant level as mentioned. However it sounds like there could be a problem in the heat control module or the blend door actuator. I would strongly recommend taking it to a professional and pay the small fee that they charge to give you the right answer and an estimate.

[Jeremy airjer W]

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Possibly a stick thermostat could cause the problem too, if it sticks wide open and then closes again.

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Newer vehicles will usually flag a check engine light if the coolant temp never reaches full opperating temp (t-stat stuck open or operating incorrectly). We see quite a few GM's with these codes.

[Huskie]

The check engine light just came on, why doesn't the low coolant light warning like come on? Bringing it in this week.

[Jeremy airjer W]

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why doesn't the low coolant light warning like come on?

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Is the coolant low?

These sensors are located in the coolant bottle. They are well known to stick so that the light is always on. A couple of light taps with a rubber mallet will usually solve this problem. In theary I suppose it would not be impossible for it to stick the other way so that the light doesn't come on. Or maybe its unplugged?