Gtpguy

I'm stumped. Been dealing with this for a year now. It's been at my brothers in phx since the 4th of July. He replaced the radiator and thermostat and tried a bunch of things but nothing has worked. The car runs fine and cool with a.c. off.

He thinks it's the a.c. radiator clogged and old or the compressor itself. I'm flying down to get it and take it back home now that it's cooler I can drive the 6 hours without need for the ac. The a.c. blows cold bit the compressor makes a slight metallic scraping sound. I'm looking for my fbody brethren wisdom now. Always appreciated.

-kevin

Pullngz

If the car runs normal temp without A/C. I would expect your second fan is not coming on with the A/C. Your adding an additional heat load via the condenser with the A/C running

If the condenser(A/C radiator) was clogged, It would impede air flow to the radiator without the A/C running, because it's directly in front of it.

Injuneer

LT1? Year? Engine? Fan setups are not all the same.

Gtpguy

93 Trans am. Previous owner installed a fan switch. Both fans work, i leave them always on high.

Gtpguy

I read that a system low on refrigerant would cause an overheating. Is it worth a shot after cleaning between the condenser and flushing it? How hard is that to do, or should I do the refrigerant first?

Injuneer

Is he basing "overheating" on the dash gauge? Is it getting into the red? If not, what temp? What temp is "cool"? And you have verified both fans are actually running?

Pullngz

Low refrigerant=Lower pressure
Lower pressure=Lower condensing temperature

A blockage in the refrgerant lines, clogged dryer, contaminates on compressor valves, clogged condenser coil, overcharged system= high head pressure. That will add a heat load to the condenser. transferring it to the radiator.

Radiator cap good? Did yo bleed all the air out? Correct LT1 thermostat? Resovior tube connected to the top port of the radiator? Pressure test for leaks?

Gtpguy

Both fans run. New rad cap. 2 new thermostats. Temp had gotten to red. No a.c. driving sat right at the first mark. Bled many times and again when the new radiator went in.

Thanks for the ac system info. Are you an a.c. tech? I was waiting for something described like that, that system is so alien to me.

Pullngz

I work in the commercial HVAC industry. If you put a new radiator, cap and T-stat in, bled all the air out. I would say it's one of 2 things, a failing A/C compressor, or water pump. Failing A/C compressor putting an extra load on the engine, causing it to run hot. Failing water pump not circulating coolant.

Gtpguy

Update: Replaced the entire system. The condenser was black, full of tiny rocks and hair. Drives nicer too, the compressor was dragging. Not cheap but I'm happy and have a warranty for it.