Engine Overheating when a/c on... help!!!
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Joined: May 2012
Posts: 61
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From: FL - Florida
Engine Overheating when a/c on... help!!!
Hey guys, here's my problem. When the car is on and operating without the a/c on, the engine temp is fine. However, once I turn the a/c/ on, within a few minutes, the engine temp display starts climbing fast, and I have to turn the a/c off and drive for a few more minutes to cool the motor back down. Does anyone have an idea what the problem could be and how to fix it? I've taken my car to a few shops, and no one has been able to fix it yet. A friend told me it might be the a/c fan that isn't working properly. It works but I think it turns off too soon and lets the motor overheat. Is there a way to rig it so the fan stays on all the time? I've lost several radiators to this problem, and I cant even use my a/c in this crazy hot weather. Any help would be really appreciated.
Racer
Joined: Feb 2014
Posts: 1,684
Likes: 70
From: SoCal 858
Check your coolant level. The typical culprit is the cooling fan going bad, heard it's common in the Lexus. I understand that taking your car to the dealership should be your last resort if you don't want to spend a grip of money.
Check out these threads for anything that sounds similar.
https://www.clublexus.com/forums/es3...ith-ac-on.html
https://www.clublexus.com/forums/es3...g-problem.html
Contact your local trustworthy indy mechanic if you need another opinion.
Check out these threads for anything that sounds similar.
https://www.clublexus.com/forums/es3...ith-ac-on.html
https://www.clublexus.com/forums/es3...g-problem.html
Contact your local trustworthy indy mechanic if you need another opinion.
Even before opening this thread and reading I thought fan malfunction. VIP161 may be right. Maybe look into the cooling components. My second guess is thermostat isn't opening when should, or water pump is going bad. I would Start with the cheapest and easier of the 2 first. Thermostat..... GL OP.
Thread Starter
Rookie
Joined: May 2012
Posts: 61
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From: FL - Florida
I have checked both fans. They work, but I'm not sure if they're cutting off early or the relays for the fans are bad. I've taken the car to multiple mechanics and none of them have been able to fix the issue. I didn't think of the water pump. I'm gonna start with the thermostat, then the temperature switch, then the water pump. Hopefully something gives. I really don't wanna take the car to the dealer.
Last edited by static88; May 15, 2014 at 08:14 PM.
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Driver School Candidate
Joined: Aug 2015
Posts: 34
Likes: 0
From: Colorado
*** Dirty Condenser Coil!!! ***
A dirty condenser coil will cause this! Remember, these cars are old!
Symptoms:
- Can overheat to the maximum, past the redline
- Only overheats with A/C on. Totally normal otherwise.
- Worsened while in stop-and-go traffic or on very hot days
- Lessened on the highway and when raising the A/C temperature setting to a higher setting
Solution: Take your car to the car wash with a high pressure sprayer and hold the tip right up against the coils and flush out with plain water. Then take your car out to the freeway to air dry the coils. Then, test if it worked.
It may be a good idea to remove the coil from the car and clean both it and the radiator coils separately since I am not sure if the debris that I sprayed out from inside the condenser coils is now stuck between the condenser and radiator coils now. But, this solution solved it 99%. The temp gauge still rose once to about 70% on a 97 degree day while in traffic, but it fell quickly after moving again and when turning the A/C off momentarily.
Good luck
Symptoms:
- Can overheat to the maximum, past the redline
- Only overheats with A/C on. Totally normal otherwise.
- Worsened while in stop-and-go traffic or on very hot days
- Lessened on the highway and when raising the A/C temperature setting to a higher setting
Solution: Take your car to the car wash with a high pressure sprayer and hold the tip right up against the coils and flush out with plain water. Then take your car out to the freeway to air dry the coils. Then, test if it worked.
It may be a good idea to remove the coil from the car and clean both it and the radiator coils separately since I am not sure if the debris that I sprayed out from inside the condenser coils is now stuck between the condenser and radiator coils now. But, this solution solved it 99%. The temp gauge still rose once to about 70% on a 97 degree day while in traffic, but it fell quickly after moving again and when turning the A/C off momentarily.
Good luck
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Joined: Aug 2013
Posts: 608
Likes: 23
From: CA
Pop open the hood. Turn on the ignition without starting the engine. Turn off the AC.
Start the engine. Note that both fans should be off.
Turn on the AC. The left hand fan, below the radiator filler, should immediately start running.
If it doesn't, you've found the culprit.
The right hand fan is linked to a thermostat and will kick in whenever the water temperature gets too hot. There may be some exceptions, but based on my experience the LH fan should run whenever the AC is on.
Start the engine. Note that both fans should be off.
Turn on the AC. The left hand fan, below the radiator filler, should immediately start running.
If it doesn't, you've found the culprit.
The right hand fan is linked to a thermostat and will kick in whenever the water temperature gets too hot. There may be some exceptions, but based on my experience the LH fan should run whenever the AC is on.
Last edited by natman; Aug 10, 2016 at 09:53 AM.
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