I have a 2007 pontiac G6 with the 3.5L V6 engine, and for the most part it’s a great car. I love that I can get 30mpg on the highway in a car that puts out over 200hp and only uses 4 quarts of oil. However, in the winter, it has this annoying problem where at a stoplight, or whenever idling, the heater stops putting out heat. This can be remedied, for a short time, by putting the car into neutral and revving the engine slightly, but wtf is with this? Is it by design, or os this some sort of flaw that only happens with mine?
It is a common problem. It is almost certainly the engine thermostat. The good news is that it tends to be a fairly cheap repair:
http://www.automedia.com/Keep_Your_Eye_on_the_Thermostat/ccr20041201th/1
My frist thought would’ve been a vacume leak.
I don’t think it’s the thermostat. The coolant temperature seems to be controlled just fine. It gets to about the middle of the temp gauge and stays there, and I get heat while the engine is under load (ie, while I am driving). It is only when the car comes to a stop/idle that the heat goes away. I’ve had cars with bad thermostats before, and the problem was the complete opposite. If you were stopped, with no airflow over the radiator, they got warm and provided heat, but when you were driving, the constant flow of air over the radiator along with the open loop on the coolant would mean you get no heat.
So, if you can explain why a bad thermostat would cause my problem, I’ll head to the dealer and get a replacement, otherwise I am sticking with the idea that it’s something else.
Have you checked your coolant level? My first guess would be that you are low and have air in the system (suggesting a leak). If the water pump can’t keep fluid everywhere and your heater core just fills with air at a stoplight, your heater isn’t going to work.
Check the radiator level, fill it up when you see that it is dry, and voila.
I vote for fluid levels and/or air in the cooling system. Everything is working fine from a parts standpoint.
Revs at idle bring back the heat? That’s the smoking gun right there. Having the cooling system set up right.
Also, listen to the water pump. If the pump has worn out, or gotten congested with crud, it may not be circulating as well as it should. If nothing else turns out to be the problem.
I’ll add, I vote for checking fluid level first.
I sure hope it’s not the water pump, this thing only has 19K miles on it. I’ll check the coolant level, thanks for the suggestions.
Does the air blow out cold, or does it stop blowing? If it stops blowing, can you still hear the fan running?
If the fan’s running but you stop feeling the air come out, you have a bad vacuum line somewhere.
Otherwise, follow everyone else’s advice and check the coolant level.
The heater requires circulating fluid to work. the faster the engine is turning the more fluid is moved through the heater. By default it will move less fluid at idle but you should still have ample flow to make comfortable heat.
At 19,000 miles you should not have any problems with this. If it’s low on fluid then it’s leaking somewhere and that needs to be checked under warranty. If it’s not then I would suspect the thermostat is opening too soon or stuck open. A properly operating system should produce heat within 5 minutes of driving so if your car takes 20 minutes to warm up then you’ve got a thermostat problem.
It’s not unheard of to get a bad thermostat in a new car. I had that happen on a Ford Escort. When I replaced the thermostat everything was fine.
Aren’t you still well within warranty? 3 years/36,000 miles is a normal minimum. I’d go to the dealer, clearly explain the problem, and have them fix it at no charge.
I was a Pontiac service manager years ago. There may be a device called a hot water shutoff valve that is not working correctly, perhaps as a result of an earlier poster’s suggestion of a vacuum problem. Regardless, the car needs to visit a GM dealer. I wouldn’t be surprised if there isn’t a service bulletin on this problem. I recall similar from many years ago. History repeats itself. Good luck.
First of all the reading of temperature gauges on modern cars is heavily dampened and the needle pretty much stays at the same place, no matter whether the actual coolant temperature rises or falls.
Now about your problem. Maybe the thermostat has stuck open and the coolant circulates at all time.
Perhaps, but if it’s warm when he’s moving why would it suddenly become cool when he stops? Same coolant, and in fact when you stop the coolant should heat up more quickly.
There must be something in the heater system that’s causing this, I’d bet it’s not engine coolant.
Keep us posted, OP.
Air is still blowing, just cold air. It gradually moves from hot, to warm, to tepid, to “holy shit, who opened the window?”
crazyjoe: Have you not yet opened the radiator cap? We’re dying here! Go out and take a look!
Sorry guys! It’s been a busy holiday season. I did get out and check the coolant level, it was probably 1/3 gallon low, so I went and bought some and put it in, and I’ll be danged if that didn’t correct my heat roblem. Now I have heat at stoplights! And when idling, too!
Thanks everyone!
Congrats! Now the next question is why you were 1/3 gallon low.
Who knows. Maybe they didn’t fill it properly at the dealership when i got the car? I will continue to monitor fluid level and see if it decreases again, and if so, rest assured I will take it in for inspection. At this time, though, a trip to the dealership would have been pretty inconvenient.
Follow up question: Umm, why? I’ve got a weird fan problem and I also suspect a vacuum leak. Didn’t think the two could be related.
And how do you find a small (possibly intermittent) leak? Can’t hear anything with the engine running. Web sites suggest things like using an unlit propane torch and seeing if the engine revs. (Really??? :eek:)