Unusual air conditioning problem

[pattsy]

I have a 1997 Nissan Maxima that overheats when I have the air conditioning on "AUTO" and the fan position is on "high." The system is blowing out alot of cold air when it is on high but the water temperature will go all the way up to the point where I have to turn the A/C off. The car will sometimes overheat when the car is stopped at a light whenthe fan is on low. The cardoes not overheat at all when the A/C is off. The thermostat was replaced about 8 weeks ago with no change in this condition. Can anyone give me any suggestions?Thanks,

Pattsy

7/29/08:I checked the radiator fans, fuses and relays. All seem to be working fine, I confirmed this by running the engine in the driveway and putting the a/c on "auto". a/c started working and the fans started running. temp climbed to its normal range. ran for 10 minutes with no problems. Took the car on the high way. After about 10 minutes the temp started climbing. Turned off a/c and temp dropped back into normal range. no derbis on the radiator. Still trying to fiqure out what to do. Anyone have any other ideas?
Modified by pattsy at 4:22 PM 7/29/2008

[CPS]

Sounds to me like the cooling fans are giving you problems. I'd check all the fuses, then the relays, then jump the wires on each individual fan to make sure the motors are spinning. I would venture to guess that the A/C fan is not turning, and the cooling fan cannot keep up with the demands that the A/C system is putting on the car. You can get an entire fan shroud assembly, with both new motors, for about $130 or so from Carquest.

[240FeVeR]

Turn the engine on, put on the AC..go under the hood and make sure the radiator fan is running. With the AC on, radiator fan should run constantly.

[Q45tech]

Remember the ac condenser transfers heat [from inside] to the air in front of radiator. This extra 40F added to ambient air may be enough to overwhelm a worn out marginal cooling system.Rehabilitate radiator, remove leaves and debris between condenser and rad. If rad is over 10 years replace with new.

Bring cooling system back to brand new or leave AC OFF.

[pattsy]

7/29/08:I checked the radiator fans, fuses and relays. All seem to be working fine, I confirmed this by running the engine in the driveway and putting the a/c on "auto". a/c started working and the fans started running. temp climbed to its normal range. ran for 10 minutes with no problems. Took the car on the high way. After about 10 minutes the temp started climbing. Turned off a/c and temp dropped back into normal range. no derbis on the radiator. Still trying to fiqure out what to do. Anyone have any other ideas?

[Syes200]

Did you make sure you have enough coolant in the radiator and the rest of the cooling system?

[Q45tech]

In driveway the engine with AC on might be producing <10 HP, on highway 30 HP normally the air flow thru rad is designed to deal with say 40 HP at 60 mph and 160 HP at 120 mph.

A 1997 is 11-12 years old roughly the time when rad is replaced to to poor performance.

Careful the aftermarket look a likes may only be 85-95% as efficient oem.

[karen wilson]

The cooling fan and radiator. It's hard to travel without the help of the A/C, and it's really a hassle whenever you're traveling and worried about the car may overheat. Clean the radiator and the cooling fan and check the coolant.

__________________________Autopartswarehouse is a must!

[pattsy]

Problem solved! I'd like to thank everyone who replied to my post and a big thank you to Q45tech. Tried everything I could think of (even borrowed a obdi to check if it was actually overheating) before biting the bullet and buying a new radiator. I realised I was on the right track when the old radiator was about twice the weight of the new one! I have been running it for about 5 days and the gauge has not moved at all! I believe it is even a little lower than it usually was. Thank you again for who replied to my problem.

Pattsy