A/C causes overheat

[Shatonapples]

For some time now, I've had this problem where, if I am driving around with the A/C on, and the car is completely warmed up (10-15 minutes of driving), the needle starts creeping up. I've heard from one of my friends that the thermo-gauge doesn't register perfectly, and that if it moves at all, you're probably getting quite hot. I will admit, it's never "technically" overheated, it's never gone into the red, because I always turn the A/C off and baby it until it cools down.

I'm a tad bit afraid of getting another bhg, so I'm curious to know if any of you have any idea why it would be heating up so very much. It may just be normal, but I can't imagine I'm the only one running 8-9psi (daily driving), stock cooling, and then running the A/C. I would be worried it's a bhg, but I already have a pretty nice aftermarket gasket in there, and it ONLY heats up when I'm running A/C.

Thanks a bunch guys,
Hank

 

[supraguy@aol]

How old is the radiator?
This exact problem used to happen to me, with a 5yr old radiator, and that's really not that old. I would drive along, no problems for as long as I wanted. But as soon as I turned on the AC, I would begin to get a temp rise within 5 minutes. If I didn't do anything about it, the temp would go all the way to redline. If I turned it off, it would settle back down within 10 minutes. I was afraid I was already getting BHG, but on a hunch(and because I wanted to upgrade anyway), I replaced my radiator with a CSR 2 row racing radiator.
I've never had the problem since.

 

[TurboWarrior]

Id recommend taking your rad out, flushing it with water, spray water through the fins to get the dirt/leaves out, and flush the system.

I don't think it will happen again after you do this.

Unless its your water pump failing.

 

[jdub]

Check your rad fan coupling...is your fan shroud in good shape?

 

[Adjuster]

My guess is the fan clutch too.

Larger radiator is a nice touch, and that CSR two rwo is a great deal, but if you don't have a good fan clutch, and shroud installed, your asking for cooling problems with the A/C running.

Replacing the fan clutch is not very hard to do, about 50.00. It might just solve your problem.

Pulling the radiator, and flushing out the debris caught up between the condensor and the radiator is not a bad idea either, but I doubt it's the cause of your problem if the radiator is only 5 years old.

The stock fan, when the fan clutch is working right, moves plenty of air. (Much more than E-fans IMHO.)

 

[Shatonapples]

Wow, that's ironic, there was a period of time recently that I thought the radiator was going out. I think I'll do that, flush the coolant system and possibly take the radiator out and give it a good cleaning.

The fan shroud is gone because my crank fan ate it, I have an electric fan with it's own sort of shroud, and it doesn't seem to have any trouble cooling unless the A/C is on, which still could be a problem with the fan. I can only assume the radiator is still 20 years old, but that's 48,500 miles.

Where can I get that CSR two rwo?

Does anyone else believe that if the thermo-gauge moves at all, that it's getting more hot than it appears? I'd never heard that until one of my friends mentioned it, and he owns a supra. He also knows a lot more than I do, so I tend to trust him, but I just want to make sure, because it's constantly making me paranoid whenever my gauge rises.

 

[supraguy@aol]

Can't remember the site that I bought mine at, but this rad looks pretty...well...
rad...Plus it's at a great price. If this product had been available 2 years ago, I would have bought it:

http://www.autozconcept.com/product_info.php?products_id=783

Fan clutch?
http://www.partsamerica.com/productdetail.aspx?MfrCode=HAD&MfrPartNumber=2653&PartType=176&PTSet=A

 

[a_sesshoumaru]

my overheats with ac because of the electric fans, i need bigger ones

 

[suprabad]

Also, if you recently recharged your a/c (especially if you converted to R34 and didn't reduce the volume of refrigerant to 80% of factory recomended capacity) you may have the system overcharged, which will cause the engine to lope at idle, and believe it or not...overheat!

Just a thought.

 

[johnathan1]

Also, if you recently recharged your a/c (especially if you converted to R34 and didn't reduce the volume of refrigerant to 80% of factory recomended capacity) you may have the system overcharged, which will cause the engine to lope at idle, and believe it or not...overheat!

Just a thought.

I had a local shop charge my AC with R143a refrigerant (stock specified amount AFAIK) and my car has not overheated ONCE in two years...no lopey idle either.

As for the OP...check that your electric auxiliary fan(s) are working.

 

[foofers]

Maybe your electric fan isn't pulling enough air through.
Do your condenser fans that turn on with the AC?

I would also recommend replacing your thermostat and radiator cap. Cheap insurance.

 

[jtran8]

If you are still running stock cooling fan then i would say cooling fan clutch , but you already replaced it with electric fan . so the only thing i can think of is the thermostat stuck close and not enough coolant flow when it needed , cause temperature keep raising when a/c turned on . MY supra and my dad rodeo had the same problem ,some how my supra got bad cooling fan clutch and my dad rodeo got bad thermostat . Check your electric cooling fan to make sure it working properly ; replace thermostat with a new one ,it cheap and easy anyway.

 

[Shatonapples]

Thermostat is brand new, and it's Toyota, and I had the problem before and after changing out the thermostat, so I'm inclined to think that it's not related. Radiator cap is possible, but I think unlikely. The electric fan may not be pushing enough air, I cannot rule that out as a possibility, especially since the Supra's radiator is pretty small, so it would probably need more CFM than a lot of American vehicles. I'm going to try recharging my A/C, as my A/C doesn't blow cold anyway, and if it doesn't solve the problem, then I can look into my other options, like radiator cap and then radiator.

Thanks a bunch for all your help guys, I appreciate it.