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Overheating with A/C on


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I have a 93 Loyale with an E82 engine and an automatic transmission. I have been driving this car for the past few months since I bought it. In our part of the country (Oregon) we don't have a heat problem until late spring and through summer. Our summers run about 95 to 105 degrees farenhiet so we need A/C. Well in testing it a nice flood of cold air was produced from the vents, but the heat started rising. The gage normally hangs at about one third up on the gauge. Well with the A/C on it got to an eighth of an inch from the red-line temp setting when I chickened out and cut the A/C.

I had plenty of coolant and the fans are both working. I am thinking about installing an oil cooler, but thought I would ask the resident experts on what they would advise. So how about it guys? What do you think?

Rick

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important question - are you absolutely sure the temp gauge is rock steady with the a/c off - this is an a/c on only issue?

 

i wouldn't concern myself with an oil cooler, that's not really going to do much for you.

 

double check those fans and make sure they are always coming on. since i believe they are relay operated it would be easy for them to work one time and not the next.

 

clogged radiators are VERY common problems. at this age if it's the original it's really due for another radiator....but you could try and flush it.

 

the a/c condensor and/or radiator fins may just be clogged. have a look, do they look really dirty and stuffed full? this is unlikely as they would have to be really stuffed full of dirt to get to this point.

 

replace the thermostat with an OEM Subaru thermostat.

 

keep your eyes pegged on the gauge...it may be worse than you know if you've never driven in the summer before. in other words it may never overheat without A/C now. but if it's only 80 now it might overheat at 100 degrees without a/c...just depends what is causing it.

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I have a 93 Loyale with an E82 engine and an automatic transmission. I have been driving this car for the past few months since I bought it. In our part of the country (Oregon) we don't have a heat problem until late spring and through summer. Our summers run about 95 to 105 degrees farenhiet so we need A/C. Well in testing it a nice flood of cold air was produced from the vents, but the heat started rising. The gage normally hangs at about one third up on the gauge. Well with the A/C on it got to an eighth of an inch from the red-line temp setting when I chickened out and cut the A/C.

I had plenty of coolant and the fans are both working. I am thinking about installing an oil cooler, but thought I would ask the resident experts on what they would advise. So how about it guys? What do you think?

Rick

 

Physically inspect the radiator, and check the electrical charging system.

 

The Radiator is probably clogged, or decrepid. If you look between the ac evaparotor and the radiator, the cooling fins may be all gone.

 

You are due for a radiator.

 

nipper

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I had the same 'problem' and I replaced my radiator (2 row), thermostat, etc. to no avail! It turns out it wasn't really overheating, it was my temp gauge. When I would turn on the AC, I would turn the interior fan up to '4' to cool things off. This would draw a lot of current which in turn caused a voltage drop in the engine ground cable, and my temp gauge would shoot up.

 

I installed a big ground cable right by the thermostat housing and the temp gauge is rock solid now. I cleaned the original grounds and while they looked ok they still had a ~50mV drop with the fan running. The temp gauge circuit is very sensitive.

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Your first task is ALWAYS to verify the problem. You may not even be overheating.

 

When the AC is on, RPM decreases, alternator output decreases, and more electrical devices are in use. Ripping into the cooling system without verifying the temp with an entirely seperate meter would be senseless.

 

GD

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Your first task is ALWAYS to verify the problem. You may not even be overheating.

 

When the AC is on, RPM decreases, alternator output decreases, and more electrical devices are in use. Ripping into the cooling system without verifying the temp with an entirely seperate meter would be senseless.

 

GD

 

Dang, you're right, senseless, no sense at all! And what a bummer too, I think I killed my last brain cell last night with that Fat Tire Ale! :clap:

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A good way to see how the cooling system is working, or if it's working, is to use an infrared thermometer at various points of the system. You may be suprised to see how hot parts of the engine can get. The radiator should be cooler on the side of the lower radiator hose where the coolant enters the engine. But if you find that the bottom of the rad or just a few rows of the rad are cooler than the rest, then that area is clogged.

http://www.maxtool.com/index/Digital_Infrared_Non-Contact_Thermometers.asp

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