#120141, "Car Overheats when A/C is not ON." Feb-01-07 07:36 AM by Louis
Hey guys...any clue about this? My car's overheating whenever my A/C is not on. Usually happens when standing still...if I have my A/C compressor on then its fine, but if it's off, it overheats. I was thinking maybe the 2nd fan is not coming on automatically and it's only kicking in when I turn on the a/c and therefore it cools off? I checked the fans and they both come on (at different intervals of course, but they do come on eventually). I would usually just leave the a/c on all the time and say screw it but lately my power steering has been locking up while the a/c is on..so i can't win either way i go. I did a search but I found people with my opposite problem, their car overheats when the a/c is ON..no word on overeating with it off. Thermostat has been recently changed as well as pressure cap, water pump was changed at 120,000 (car has 160,00) and radiator was replaced @140,000 as well. Damn overheating always comes back no mater what i do, may behave for a few weeks or month(s) but inevitably comes back. I have been meaning on doing some cosmetic stuff to my car that needs to be redone (redo headliner, etc..) but i stop short of doing it because i keep thinking this overheating issue is going to drive me to dump the car. ps. it's been to satan quite a few times and still acts up
#120142, "RE: Car Overheats when A/C is not ON." In response to Reply # 0
Is you cooling system full? My car would overheat when it was sitting still, because it was a little low. Next time the engines cool take off the pressure cap and take a look.
#120143, "RE: Car Overheats when A/C is not ON." In response to Reply # 1 Feb-02-07 09:58 AM by WIDECLIPSE
Your second fan comes on if a) the ac is on, or b) if the car gets too hot. I would definately make sure you have enough coolant. Try burping the system and if it still overheats, you may have a leak somewhere. Water pump, water tube from the pump, radiator hoses, radiator, t-stat housing, metal tube or hose running from the t-stat housing, heater hoses, heater core, or headgasket. That's all that could be leaking coolant.
Definately find out if you have enough coolant or not, but if you can't find it right away, search for the fan wire mod. This will make the second fan come on with the first one. It'll bandaid the problem until you find out what it is.
#120144, "RE: Car Overheats when A/C is not ON." In response to Reply # 2
Isn't the radiator supposed to be full to the neck when it's cold? I have noticed that when i check my coolant level when cold the radiator is not full, yet the reservoir bottle had more than enough...like it's not flowing back to the radiator... Also today I noticed it started overeheating at high speeds in the highway (80 plus), nothing too major cos i slowed down and took it easy but the needle was definitely starting to climb. Right now the car's hot form a long drive so I'll re check coolant level once its cold....
#120145, "RE: Car Overheats when A/C is not ON." In response to Reply # 3
Do a leak down..as was already suggested. I would also flush the system if you didnt find any leaks. Possibly test radiator flow, as your radiator COULD be shot.
#120146, "RE: Car Overheats when A/C is not ON." In response to Reply # 4
I checked the coolant level and it was far from full when cold. I poured enough to fill it to the neck and then poured some off the reservoir cos it was past the cold line...I guess I'll do a leak check like you guys suggested, if not then, damn i guess maybe the radiator might be shot.... Thanx for the help guys!!
#120147, "RE: Car Overheats when A/C is not ON." In response to Reply # 3
Originally posted by Louis Isn't the radiator supposed to be full to the neck when it's cold? I have noticed that when i check my coolant level when cold the radiator is not full, yet the reservoir bottle had more than enough...like it's not flowing back to the radiator...
check the tube in the reservoir. if a perfect vaccum cannot be created then when the fluid in the main tank cools and condenses it will not be able to "suck" the fluid in the overflow back. check the tube for leaks as well as the connections in the cap. also be sure the end of the tube is fully submerged all the way at the bottom of the overflow tank.
mine was leaky before and this basically creates a situation where coolant can overflow but never flow back. over time this drains your radiator.
#120148, "RE: Car Overheats when A/C is not ON." In response to Reply # 6
Thanx guys, I took it to get plugged to the computer and they found the "water temperature sensor" was shot. I'm not too familiar with this but from what they explained this was causing the main fan not to come on at the desired time or at all (no communication..). This sensor was replaced as well as the radiator cap. I'll keep an eye on things for the next few days to see how it behaves. I'll check on the reservoir hose as well as suggested for the issue of it not sucking back the coolant... I drove it back home with no a/c and it behaved, although it wasn't a long trip...we'll see once i get in highway speeds as well how it works out..
#120149, "RE: Car Overheats when A/C is not ON." In response to Reply # 7
Originally posted by Louis Thanx guys, I took it to get plugged to the computer and they found the "water temperature sensor" was shot. I'm not too familiar with this but from what they explained this was causing the main fan not to come on at the desired time or at all (no communication..). This sensor was replaced as well as the radiator cap. I'll keep an eye on things for the next few days to see how it behaves. I'll check on the reservoir hose as well as suggested for the issue of it not sucking back the coolant... I drove it back home with no a/c and it behaved, although it wasn't a long trip...we'll see once i get in highway speeds as well how it works out..
Good deal! Of course, you'll hate to hear that's a $20 sensor at Autozone, right? Still wouldn't hurt to check the coolant level in the system once the thermostat opens.
Since it was mentioned, but not in too much detail, what you want to do is start with a cool engine, then remove the radiator cap. (Which should be up by the head, not on the radiator, by the way.) Start the engine with the cap off and let the engine get up to speed. As you see the level in the coolant flowing through the hose drop, add a little more. Once the engine gets up to operating temperature, you'll be able to tell. Wait for all the bubbles to stop, then top it off, replace the cap, and take it for a spin.
Overheating while moving means you're not getting sufficient coolant flow through the radiator. If you run your heater full blast and it doesn't blow hot air, it's the same problem. Food for thought, sir.
#120150, "RE: Car Overheats when A/C is not ON." In response to Reply # 8 Feb-06-07 01:42 AM by Louis
Originally posted by DR1665 Good deal! Of course, you'll hate to hear that's a $20 sensor at Autozone, right? Still wouldn't hurt to check the coolant level in the system once the thermostat opens. Since it was mentioned, but not in too much detail, what you want to do is start with a cool engine, then remove the radiator cap. (Which should be up by the head, not on the radiator, by the way.) Start the engine with the cap off and let the engine get up to speed. As you see the level in the coolant flowing through the hose drop, add a little more. Once the engine gets up to operating temperature, you'll be able to tell. Wait for all the bubbles to stop, then top it off, replace the cap, and take it for a spin. Overheating while moving means you're not getting sufficient coolant flow through the radiator. If you run your heater full blast and it doesn't blow hot air, it's the same problem. Food for thought, sir.
I kinda figured the sensor would be cheap as hell elsewhere....but i also knew if i just told them to leave it as is, they would have charged me with a "diagnostic fee" that would have probably cost me almost as much as having them replace it there...and no I aint saying how bad I got "raped" with paying for this sensor haha.. Oh well you live you learn. I'll definitely check on the coolant to make sure its flowing properly...oh and while driving to work all happy because my car wasn't overheating, my serpentine belt snapped making a loud popping noise in the engine bay that freaked the shit out of me. Now I'm driving around with no a/c and no power steering till i can get a belt because the size isn't a popular one, and everyone has to "special order it".(AFX pulley belt...i mean i go tru these belts like candy what is it with these things squeaking and popping)..oh well at least i ain't overheating...yet!
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Still wouldn't hurt to check the coolant level in the system once the thermostat opens.