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Car Thermostat Issue?
Ganluan
Registered User regular
Registered User regular
A month or so ago I got the radiator replaced in my Elantra... it had cracked and was leaking coolant. They traced the cause to a busted thermostat and replaced that as well.
Recently, the car's AC stops putting out cold air when the car is idling. As well, the heater is putting out cooler air while idling. While actually moving, the AC/heater work fine. Would this be related to the thermostat, or caused by something else?
Recently, the car's AC stops putting out cold air when the car is idling. As well, the heater is putting out cooler air while idling. While actually moving, the AC/heater work fine. Would this be related to the thermostat, or caused by something else?
Ganluan on
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A. None is circulating or
B. Its empty.
Either way this is bad news because your engine can seize up.
If your heat works the same way as in a car I used to have, then the heat is actually generated by hot engine coolant passing through the Heater Core, which is just a little radiator. The blower passes air over it and voila, hot air.
So if this is how they still heat them newfangled automobiles, then your car is probably running coolar than usual. Is the temperature guage showing the same thing it used to? Is the car taking longer to warm up than it used to, or is it the same? It could be that the car is just running cooler because of the new radiator/thermostat. It could also be that the new thermostat is bad and stuck open (that would be true if the car was taking a really long time to heat up).
Well that would explain a heat only problem. Now I just read the part about it blowing not-so-cold air at idle, and that pretty much debunks my theory. But I don't want to erase all that stuff I wrote, so I'm gonna leave it.
My VW doesn't blow cold air at idle, and I have no clue why.
This was my thought as well.
As for the A/C, it's not connected to your engine's cooling system at all. It's not uncommon for it to get warmer when you're idling, as the compressor is hardly turning and you're getting little airflow through the condenser. Your refrigerant might be low, but unless you're really upset about the idle thing I wouldn't worry about it. A/C is expensive to work with.
I'll check the refrigerant again to make sure.
Before the radiator problems, the AC stayed ice cold even while idling for extended durations. Now it gets warm enough that it almost feels like hot air if you idle for more than a few seconds. It seems really odd the heater won't heat while idling either, since that also worked before.
The temp gauge is at the same level it was before the radiator problems.
By refrigerant, I mean the stuff in the A/C system. Unless you have a pressure gauge, you can't check it yourself. If it worked fine beforehand, though, that's probably not it.
When the car is idling, do all the heater controls work like normal? Does it switch from defrost to floor to vent? You say the heater blows cool at idle, is there a difference in temperature between the hot and cold settings when it's doing that?
Ah I thought you meant coolant, my fault.
I actually don't recall if there's much of a difference between hot/cold settings while idling with the heater or AC on. I'll check again, but what would that indicate if there's not a difference?
When you turn on the heat, it pipes the hot coolant through the heater core (it also does this when the car gets hotter). If the thermostat is sticking shut then it won't flow and you'll get cold air out the vents.
If your heater core is gone... "typically" you end up with some fog coming from the vents (and covering your windshield in antifreeze) or you'll notice a leak towards the middle of the car (around where your center console sits.
I'd also check the coolant level to be sure that everything is fine on that part. The temp gauge is not the best at determining the actually temp your motor is running at (on my focus, 99% of my coolant had leaked adn the temp gauge didn't move, i only noticed because i was getting cold air through the heater with the heat turned on)
I found the coolant tank but it's tucked under other stuff near the radiator, and hard to see in. I don't see much coolant in it though, but I'm not sure how to tell if it's at the right level or not. It's a long narrow opening which makes it difficult to gauge.
Well, since your problems happen only at idle, the first thing that popped into my mind was a vacuum issue. The flaps inside your dashboard that switch between heat/cool/etc. are operated by vacuum, and if there isn't enough they can fail to open or open half-way. It's not uncommon to forget to reattach a vacuum hose (or crack it) when you're reassembling things, especially when they replaced your thermostat. A small leak would be apparent at idle (when your engine isn't making much vacuum), but wouldn't be noticeable while driving.
So you'd be driving along, heater working just fine, but as you come to a stop the vacuum holding the heat flap open would slowly diminish, causing it to close. Poof, you have cool air. Same thing with A/C. The easiest way to test this is to just sit at idle and change the air routing around (it's operated by the same vacuum). The defrost vents are the "default" setting when anything breaks, so see if it'll come out the floor or vents.
That's the only problem I can think of that would effect both heat and A/C at idle. It could be two completely unrelated problems.
Edit: Take the radiator cap off to check the coolant level (when it's cool!). If there's coolant at the top of the radiator, you're good.