Why does the car run hotter when the air is on?

[Ostang351]

Just replaced the thermostat (180deg) and flushed the radiator. It is very hot here in Florida (95 deg), but the car runs at a decent temp. When I turn the air on, it moves another whole tick (on the tempgauge). When I turn the air off, it slowly drops temp again. Is this normal? There are no leaks. Should I ad water wetter? Stock fan and radiator (I think). Thanks!

 

[fordman54935]

The AC compressor (when on) places extra load on the engine and therefore the cooling system as well. That is why cars with electric fans have relays that turn the fan on whenever the AC compressor is on. It seems to be normal for the temperature to raise a little when the AC is on. I wouldn't worry about it much unless the temp increase is pretty drastic.

Be thankful.....your AC works I've been thinking of recharging mine (I have a friend who is an AC tech) but in the Wisconsin climate it doesn't justify the expense of the R-12. (I lived in FL for 5 years and I know your loving that AC about now)

 

[Ostang351]

You betcha....thanks for the response!

 

[FrdMustangCpe]

sorry for chiming in on your post but, there is a leak somewhere in my a.c. it hasnt got too hot out here so im not really worried about it. Does anyone know if those leak fixers work? or would i have to do the U.V thing and hope for the best. the previous owner recharged it before i took possesion and it lasted about a week....not really using it.

thanks

 

[ninjacoupe]

Yea the extra load and the air going to your radiator is also being heated by the heat exchanger in front.

 

[cardudeusa]

The AC compressor (when on) places extra load on the engine and therefore the cooling system as well. That is why cars with electric fans have relays that turn the fan on whenever the AC compressor is on. It seems to be normal for the temperature to raise a little when the AC is on. I wouldn't worry about it much unless the temp increase is pretty drastic.

Be thankful.....your AC works I've been thinking of recharging mine (I have a friend who is an AC tech) but in the Wisconsin climate it doesn't justify the expense of the R-12. (I lived in FL for 5 years and I know your loving that AC about now)

You should consider converting your car to R134a, you can get the kit for like $30 and 10-15 minutes later you have ice cold air. I just did mine about a month ago and am glad I didn't wait any longer to. This FL weather was killin me.

 

[5spd GT]

You should consider converting your car to R134a, you can get the kit for like $30 and 10-15 minutes later you have ice cold air. I just did mine about a month ago and am glad I didn't wait any longer to. This FL weather was killin me.

So where do you get this kit?...any writeups on doing it...

Thanks...

 

[86Cobra]

The AC compressor (when on) places extra load on the engine and therefore the cooling system as well. That is why cars with electric fans have relays that turn the fan on whenever the AC compressor is on.

That's not entirely correct. The a/c needs airflow through the condensor in front of the radiator in order to work properly. So, stock electric fans turn on with the a/c to provide this airflow.

 

[04sleeper]

Next time you are driving around in the middle of summer, like now, and you are running your A/C for a while, pull over and touch your condensor.(OK Don't really do it because it might burn you.) It gets very hot and it sits right in front of your radiator and heats up your radiator.

 

[gt90stang]

I measured the temperature rise of the air going into my radiator to be about 45*F due to running the AC. So if its 100*F the air into my radiator is about 145*F with the AC on. Not much of a temperature difference to cool the motor! This is with a Lincoln Mark VIII fan.

Don

 

[Ostang351]

It is already converted to the new air system. Thanks for the response