Engine getting hot with AC on
06-23-2004, 08:36 AM
#1
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Engine getting hot with AC on I have a problem with my car’s engine temperature getting hot (almost to the red) when the air condition is on. It stays cool as long as I do not have the AC on. If I am idling the temperature will rise noticeably and only cools off slightly if I get on the highway. When on the highway with the AC on and then I turn it off the temperature will cool down very fast so there is a definite relation between the AC and my temperature problems. Has anyone else ever experienced this problem? I have a 160 thermostat and my fans are programmed accordingly. I thought about it being more load on the engine, but I can run my car extremely hard and it won’t get as hot as it does after the AC has been on for a couple minutes. I’m confused please help. My major engine mods are listed below.
PP 5.7 stage 2 heads, 228/228 cam, TCI 3800 stall, LS6 intake, Pace LT Headers
Thanks
PP 5.7 stage 2 heads, 228/228 cam, TCI 3800 stall, LS6 intake, Pace LT Headers
Thanks
06-23-2004, 09:44 AM
#2
It sounds like the radiator fans are not coming on.
You have one fan that comes on and goes off at predetermined temperature settings.
The second fan comes on when the compressor is engaged.
It sounds like the second fan isn't coming on.
1. Turn on the AC when cold and see if a fan runs.
If no,
2. check the fan relays ... swap fan 1 for fan 2 and vice versa and go back to #1
No change
3. check the plug in connections to make sure the fans are plugged in and go to #1
No change
4. let the car come up to temp and see if a fan turns on
If no, swap the last wiring connection into the first fan and see if a fan comes on
If still no, I would suspect a burned out fan motor.
Chances are good, though, you have a bad connection or a blown relay.
Also check in front of your radiator for debris and between the radiator and AC condensor for debris. I had a WalMart bag get sucked in between the condensor and radiator before.
HTH
You have one fan that comes on and goes off at predetermined temperature settings.
The second fan comes on when the compressor is engaged.
It sounds like the second fan isn't coming on.
1. Turn on the AC when cold and see if a fan runs.
If no,
2. check the fan relays ... swap fan 1 for fan 2 and vice versa and go back to #1
No change
3. check the plug in connections to make sure the fans are plugged in and go to #1
No change
4. let the car come up to temp and see if a fan turns on
If no, swap the last wiring connection into the first fan and see if a fan comes on
If still no, I would suspect a burned out fan motor.
Chances are good, though, you have a bad connection or a blown relay.
Also check in front of your radiator for debris and between the radiator and AC condensor for debris. I had a WalMart bag get sucked in between the condensor and radiator before.
HTH
06-23-2004, 03:47 PM
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I have the same problem. I know for a fact both my fans are on. Sometimes when I shut the car off, coolant will bubble out of the overflow if the engine has heated up from having the ac on. I am thinking it is either my Whisper Ram Air (No bottom plate) or my tranny cooler which is somewhat mounted in front of my radiator. BTW with the ac off my car never reaches the first mark on the gauge and never goes above 185 (autotap). This is in 90 degree weather, beating on the car. Definately wouldnt mind finding a solution.
Last edited by TRYMYZ; 06-24-2004 at 08:15 AM.
06-23-2004, 10:17 PM
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Checked tongiht and both fans are good, also there is not any foriegn substance in front of the radiator. Anyone else have any ideas. Thanks for the ideas so far.
06-24-2004, 07:20 AM
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I just fixed the exact same problem on my car last weekend, the only difference being I have the stock thermostat and programming.
My car would run a little hot while cruising, but turn on the AC and it would jump up about 30 degrees and wouldn't come down unless I turned the AC back off. Fans were operating as they should have been.
Anyway, I replaced the thermostat, coolant, and radiator cap with GM parts and it is back to normal now.
My car would run a little hot while cruising, but turn on the AC and it would jump up about 30 degrees and wouldn't come down unless I turned the AC back off. Fans were operating as they should have been.
Anyway, I replaced the thermostat, coolant, and radiator cap with GM parts and it is back to normal now.
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06-24-2004, 01:33 PM
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The radiator cap is a key piece in maintaining a properly pressurized coolant system. 18 psi for the LS1 system. If the radiator cap is faulty, and unable to maintain that pressure, the coolant will boil. Pressure increases the boiling point of the coolant.
A cap is about $7 fro GM, and a new thermostat is around $25 from GM. Since you have the Hypertech 160 thermo, you could pull it out and check it in some 160 degree water on the stove...then see if it opens all the way.
Draining the coolant and pulling the thermostat is real easy...only takes a few minutes. I don't think you need to go pay anyone to do a coolant flow test. Check the cheap stuff first, then work your way up.
A cap is about $7 fro GM, and a new thermostat is around $25 from GM. Since you have the Hypertech 160 thermo, you could pull it out and check it in some 160 degree water on the stove...then see if it opens all the way.
Draining the coolant and pulling the thermostat is real easy...only takes a few minutes. I don't think you need to go pay anyone to do a coolant flow test. Check the cheap stuff first, then work your way up.
06-24-2004, 01:36 PM
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Originally Posted by NOBR8KSS
The radiator cap is a key piece in maintaining a properly pressurized coolant system. 18 psi for the LS1 system. If the radiator cap is faulty, and unable to maintain that pressure, the coolant will boil. Pressure increases the boiling point of the coolant.
A cap is about $7 fro GM, and a new thermostat is around $25 from GM. Since you have the Hypertech 160 thermo, you could pull it out and check it in some 160 degree water on the stove...then see if it opens all the way.
Draining the coolant and pulling the thermostat is real easy...only takes a few minutes. I don't think you need to go pay anyone to do a coolant flow test. Check the cheap stuff first, then work your way up.
A cap is about $7 fro GM, and a new thermostat is around $25 from GM. Since you have the Hypertech 160 thermo, you could pull it out and check it in some 160 degree water on the stove...then see if it opens all the way.
Draining the coolant and pulling the thermostat is real easy...only takes a few minutes. I don't think you need to go pay anyone to do a coolant flow test. Check the cheap stuff first, then work your way up.
06-25-2004, 10:05 AM
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There is a noticable difference between the speeds. With the engine running you really can't hear the fans when they are on low, but you can definitly hear them when they are on high. Sorry I don't have a better explaination. 
