Well at 94 degrees I broke down and I'm running the AC. No AC on in town or light highway under 200 degrees. AC on in traffic 30 minutes temperature up to 240ish. Would not even start after I turned her off at the store. Why such a difference in temp with the AC on? :mad

 

The 'cool' from the a/c has to be given off at additonal heat, so that heat from the car interior is transferred to the area in front of the radiator, heating the air coming in over the engine cooling area....so it's not so efficiently cooling the engine anymore....in simple physics that is what happens....

if you want a complete mechanical automotive explanation, I"m sure someone else will oblige....

GENE

 

With the A/C on you will have some temp increase possible because of the extra power required to run the compressor. The main reason for the extra heat though is because when your A/C is on the air coming through you conderser(which is in front of your radiator) is being heated as a result of your A/C doing its job. So now your gettin already warmer/hot air into your radaitor which will slow down the rate of heat transfer. Make sure your fluid level is good first off and then check to see if your fan clutch is working. You should be able to feel some drag in the clutch if you spin it. Also check to make sure the front of your condenser and any visible parts of your radior are clean and dont have any bent fins.
good luck
Kevin


[Modified by 71vettman, 10:03 PM 5/9/2003]

 

Another thing to check, are your radiator seals. Your fan needs to be able to pull the maximum amount of air through. If these seals are shot, you're not going to be able to pull the air through as efficiently. I swapped these out, and it made a big difference. Dr. Rebuild sells a kit...It's pretty easy to put in.

 

Something that gets overlooked is the A/C its self. The heat from compression and the heat from the interior of the car can easily cause the condenser temp. to exceed 200 deg. One thing to check is to make sure the system is fully charged. The compressor is cooled by the cool freon coming from the evaporator coil. If the system is low then the freon will not be cool at the compressor thus causing condenser temps to rise. You should be able to grab the suction line (large one) at the back of the compressor and it should be cool to touch and sweating with the compressor running and car doors closed.
Another thing to watch is if the car idles for a while with the a/c on as stopped in traffic.The mechanical parts (water pump, radiator seals, fan shroud, fan clutch, this is were a heavy duty fan clutch pays off) need to be in top shape. If the airflow is not sufficient then it will cause a domino effect. The airflow will not be sufficient enough to cool the a/c condenser and the a/c will lose its efficiency causing the interior temp. to increase, this intern will cause the cooling effect of the freon entering the compressor to be lost and the condenser temps will increase.
Hope you can make sense of this. I think I confused my self. Just trying to give you something to toss around. Hope this might help.

Neal
:)

 

I have two Spal 11" fans (pullers) on my radiator.....and one 10" pancake (pusher) fan on my condenser.....When I run my A/C, the condenser fan is running too.....Water temps are 180 and my oil temps never exceed 200.....The condenser gets real hot and it will increase your water temp.....with three fans on my car will creep forward without stepping on the gas :jester :D :flag :seeya Cappy

 

You may want to also check the radiator for possible blockage internally. You can pull it out and have checked/cleaned by a radiator shop.....

 

is this a new behavior or has this always happened? If new, I'd agree with the low freon and/or bad fan clutch scenario.

If the car has always been like that I'd say put in a Stewart High flow water pump, their modded t-stat, and switch to water with rust inhibitor for coolant (per Stewart's recommendation if not living in freezing climate). My car was running 220-240 at hwy speed with or without A/C, and 215-210 around town. Since I installed the new pump I am at 160-180 all the time. :cool: