help? I have a greddy lude. whenever the a/c is on, it overheats. as soon as I turn the a/c off, it cools down. thermostat, fan switch, compressor have been replaced in the past year. I've bled / burped the coolant. both fans work.

 

How close is your manifold/downpipe to your radiator? You could try coating the mani/dp or using heatwrap on the DP.

You could also try upgrading to better flowing fans or a better radiator.
Out of the two, I would opt for the fans first as it is cheaper than a radiator. HT sponsors have slim fans for pretty cheap, 105 shipped for 2 12" fans, they draw a lot more air than stock fans.

 

is your radiator clogged? looks like it.

 

I would try and get an aluminum replacement radiator thats a little more efficent. http://www.radiatorexpress.com/default.asp
You can find an aluminum one row replacement there. It should be a bit better than stock and you wont loose anyroom.

 

hmmm... only overheats when a/c is on. not under the hardest driving or boosting or any other. only a/c. is it just a radiator / fan upgrade issue? manifold or dp is not close at all. the turbo is about a 1/2" from the fan shroud which is about 3.5". just like to hear all ideas before gettin a new radiator / fans. but then i guess the upgrade can't hurt anyhow...

 

The upgrade definitely doesn't hurt, however if you're on a budget, I think upgrading the fans first is cheaper than a new rad. Just food for thought.

 

new rad. or manifold coating wouldnt be a bad idea can reduce the radiant heat alot

 

I have had that problem before... I swapped to an aluminum race radiator and also to a mugen t-stat, fan switch, and radiator cap. All of which work together to lower the engine temp as well as raise the BP of the water by increasing the pressure. the higher the pressure, the higher the boiling point... new fans would be a good idea too... ****... you might as well heat wrap the mani/ turbine housing/ dp. don't wrap the impeller side, because you do not want to hold heat in that side, you want it to stay out, which it will do on its own unwrapped.

 

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you can check if the radiator you have is clogged before throwing money at what you think could be the possible culprit, warm the car up and using a temp gun if you have one check if there are any spots on the radiator that have a major temperature difference. This would be one way to check it but I dont know how crowded your engine compartment is but if its not too bad you might be able to put your hand on the radiator and feel around but thats probably unlikely.

Good Luck