I know nothing about cars other than I get in and drive them. In a pinch I can put in windshield wiper fluid.
Here’s the question: does the heating system in a car only blow warm/hot air while in motion? When stopped, should it still be circulating the heated air, or does it cool off?
My beloved Princess (2004 Chrysler Sebring 'vertible) seems to be doing the latter. Is she sick or is this typical?
It almost sounds like someone removed the thermostat. The car should get up to temp and hold that temp while driving and idling. The water supplying your heater should be comming from the engine instead of the radiator. If the thermostat has been removed the water would continue to circulate no matter how cold it was and in cold weather the engine temp could drop rapidly while idling. Maybe your thermostat is stuck open.
An internal combustion engine produces a lot of “waste” heat, which is normally dumped into the surrounding air via the radiator. A car’s heating system uses this to supply heat to the passengers.
If the engine is running (even when the car is not moving, and the engine is consequently not working very hard) there’s enough waste heat to keep the passenger compartment comfortable. This presumes that things are working properly, and the weather isn’t savagely cold. (Below something like -30C, an idling car might not keep its passengers fully happy.)
It’s also possible there is something wrong with the heat manifold system - I don’t know if a 2004 still uses engine vacuum to control the heater flaps, etc. but in older cars, problems with vacuum from the intake manifold would cause the internal heat/cool air flaps to mis-operate. It could be that when the car stops and is at idle, either vacuum controllers or electric ones are failing. Not knowing the systems on that car, this is a WAG… but in any case it could be unrelated to how much heat the heater core has to pass along.
There’s other things it could be, but this is a pretty classic symptom of having air in the cooling system. First thing first, check your coolant level. Secondly, it may be necessary to bleed the air out of the cooling system. A quick google shows that the Sebring does have a bleeder valve, which means it should be pretty easy (and suggests that this is a common problem on these cars). Here’s a picture of the valve.
It should be pretty easy to bleed yourself-- wait until the engine cools off, start it, and then slowly loosen the brass fitting. Air should start coming out of it, but eventually you should start getting a sputter and then a steady stream of coolant. Be ready to close the valve when that happens and have rag handy to wipe up the little bit that comes out. Then you should be good, although if the problem comes back you might have to start worrying about a leak or (knock on wood) a bad head gasket.
Oh, one more belated diagnostic question-- does this car have a temp gauge, and if so is it still reading normal? I suspect it is, which would point towards air in the coolant or some other flow issue as opposed to the engine actually cooling down at idle.
I’ll reiterate what some of the others already said.
Is the interior fan blowing? Does it blow air while you are sitting still in all speeds? Does it blow on the highest speed only?
Is there an engine temp gauge on dash and does it read about half way up the gauge after driving about 5 miles?
Have you had any engine or cooling system work done in the last year or so?
If the fan isn’t working at all, then you probably need a new blower motor unless something simple like a fuse blew.
If it works only on High, there’s a resistor in some fan wiring that can cause this. Not an expensive fix.
If the fan blows at all speeds, but just not much, then it could be a clogged cabin air filter, if so equipped. Have you ever changed it.
If air only blows out the defroster and not any other vents, that’s another topic.
If the thermostat is missing or stuck open, a new thermostat will make you happy.
If someone has done engine or cooling system work on the car, it’s possible that there’s an air bubble in the system which needs to be purged. Some vehicles have special instructions for getting air out of heater cores.
Uh. You have checked the fluid level in the cooling system? If it’s low, that could cause it. I’m not just talking about the external reservoir either. With the engine dead cold, open the radiator cap. There should be coolant all the way up to the top. If not, buy a gallon of pre-mixed coolant and pour it in the radiator. Might want to use a funnel. Also top off the reservoir to just above the Cold marking on it. After driving it around some and letting it cool off, check the fluid levels again and top off as necessary.
The thing with wires is probably the engine temperature sensor. Above it in the picture is the bleeder valve – it has a hex to allow a wrench to open and close it, and a nipple for the air (and then coolant) to flow out from.
It sounds like the engine cooling system (takes heat out of the engine’s guts so it doesn’t melt) is low on coolant (water/antifreeze mixture). This means instead of being full of liquid, it has some liquid and some air, as mentioned by GreasyJack and JerrySTL. When the engine is turning at a slow speed, as when sitting still at idle, it doesn’t circulate enough hot liquid to keep heat in the heater core. When the engine is turning faster, such as when driving down the road, enough liquid flows through the heater core to give you some heat. You’ll probably find that if you rev the engine up in park or neutral while sitting still that you then get some heat.
Most likely this means there’s a coolant leak which has been gradually losing coolant and sucking in air. If this condition isn’t rectified, it will get to the point that there’s no heat from the heater at any time and the engine, not having enough coolant to get the heat out of it, will overheat. Engine overheating can cause expensive damage, so please have it tended to as soon as possible.
There are other things besides a simple leak that can cause coolant loss, but usually they would also cause overheating already. We’ll hope it’s just a leak.
To clarify for those who might want to do this themselves:
Wait for a dead cold engine, to avoid getting a geyser of hot coolant in your face.
Open the pressure cap (could be on the radiator, on the engine, or on the surge tank depending on the vehicle). If the cap is on the radiator or on the engine, fill with coolant (50/50 mix of water and antifreeze) to where the cap sits and to about halfway up (or to the “full” line) of the overflow reservoir. If it has a surge tank, fill to the “full” line.
Start the engine and watch the coolant level in the radiator, engine, or surge tank. It will likely drop as some air burps out of the system. When the level starts to rise, hurry up and replace the pressure cap.
If it has a bleed screw, crack it open and watch what comes out. When it’s a steady stream of liquid, hurry up and close it.
Let the engine heat up fully and then cool down completely again. Check the coolant level, and top up (and rebleed) as needed.
If it isn’t any of the things already suggested, and it it blows warm when moving but cools off when not moving (engine still running). It could be the water pump. It’s not a common thing but I’ve pulled a few off and found the impellers had corroded down to almost nothing. This makes it hard for the pump to move the coolant unless the RPM’s are higher than idle (like when the car is traveling).
you guys are awesome. thank you. i did indeed get a coolant flush and replacement recently, so i suspect it might indeed be air in the system. if not, then Princess will be off to the car doctor.