Issues with HEAT today. Please help.

[Wolvereen]

Hi all, new to the forums obviously. :-)

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Anyways, I was hoping that I might get a little help from som members here before I have to take my car in (which is hard because of my job hours).

I have a 1999 Pontiac Grand Am GT 2 door.

All through out the day, I noticed this issue. My temperature gadge would get to about 180 to 200 (straight up and down) and I would turn on the heater. No heat would come out at all. I tried turning the heat all the way up to 5, no luck still cool air (wasn't COLD air though).

Everyonce in a while my temperature gadge would creep up high to about 220. THen when I turned the fan back up to 5, it would creep back down to 200. I had a blast of hot air at this time, then it would go back to cool air again. Today, coming home from work though, it seemed warm for the most part (not as warm as normal, but at least putting out some warm air).

The problem doesn't seem to match anything I searched for in the forums. Can somebody lend me a hand?

Thanks!!



Oh, also, just out of curiosity. Am I the only one whose Pontiac has begun to just nickle and dime them to death? For a '99 that I haven't driven hard (keep quite good care of it actually) and there is 78K on it, it just seems like something goes wrong with it almost every other month.

[GTP Dad]

Change the thermostat make sure the fluid is a proper mix. It sounds like the thermostat is stuck in the open position. Usually it is the other way around. You may also want to check to make sure the fans aren't running all the time if they are look for a malfunctioning temperature sensor.

[Slade901]

To me, that's a sign of a failing Water Pump. It happened to our vehicle and for about 1 week of noticing that the temp gauge would go to 220 degrees, I've check the coolant level and it was close to the level but I suspected water pump. I've idled the vehicle and shine a light directly at the water pump weep hole and sure enough after idling for 10 minutes or so, water was dripping at the weep hole. Replaced the water pump and temp gauge is fine and back to normal.

[Wolvereen]

Would that cause no heat to come out though?

Thanks by the way for the reply, I appreciate it!

[Slade901]

You heat/cold selector is probably have a problem as well. Is your heat/cold selector a manual knob where you turn left to right to select cold or hot?
OR
Is your heat/cold selector is a push button type?

Heat/cold selector that uses a knob could have it's inside stem cracked and not turning the heat/cold selector the way it should to the proper setting.

Heat/cold select that uses a push button type is usually controlled by a vacuum and hoses. Some of those vacuum hoses that control the heat/cold selector is also link to the cruise control vacuum hose. If the vacuum hose shared by cruise control and heat/cold selector is broken somewhere, then the heat/cold selector would not operate properly and will be stuck at cold position to let cold air close to 99%. You can test if the cruise control is working or not by using the cruise control while drive and if it works then the vacuum hose is fine. If the cruise control is not working then you know the vacuum hose has problem.

[Wolvereen]

Originally Posted by Slade901

You heat/cold selector is probably have a problem as well. Is your heat/cold selector a manual knob where you turn left to right to select cold or hot?
OR
Is your heat/cold selector is a push button type?

Heat/cold selector that uses a knob could have it's inside stem cracked and not turning the heat/cold selector the way it should to the proper setting.

It's a knob that controls it. The knob cracked about 6 months ago and I replaced it. I definately feel SLIGHTLY warmer air when I turn to hot, but nowhere near where it was before. This morning on my way into work it finally got warm as my engine hit 210 degrees or so. Normally I feel warm air at 150 degrees....

[Chameleon-kat]

One other possiblilty is low coolant level, that can cause temperature flucuations as well as heat/no-heat conditions. If level is low, and given its a '99' 3.x engine, might want to consider the infamous intake manifold gaskets.

[Wolvereen]

Just had a minor update..

I was driving home for lunch and noticed something.

When at a complete stop (stoplight) I turned my selector knob from MaxAC (recycled air) to Upper Vent (1st position to 2nd position) to experiment. I heard a sound like a flap shutting, followed by a vibrating noise for jsut a split second (as if something were rubbing).

Does that sound familiar to anyone?

Thanks again for all the help!