When I turn off the a/c the car heats up!

[DC/NH]

When I'm out cruising along a senic road with the top down, I turn off the a/c. Since I have the top down the a/c is a waste but when I do this the engine gets very hpt. I turn the a/c back on and it foes back to normal. How does someone ride with the top down and no a/c?

DC

 

[Edmond]

I think it's because when the AC is turned on, the fans to cool the radiator are also turned on.

 

[*89x2*]

So then why does my car (C4) run hotter w/ the AC on???

dual fans, BTW - TIA

 

[rrhayden]

When you have the AC on are the fans running? When the ac runs the computer commands one fan to run to keep air flowing through the radiator and condensor.

If you get hot when you have the ac off, it sounds like you are loosing airflow somplace. Have you checked for obstructions on the radiator or between it and the consenser?

 

[DC/NH]

radiator is clear as a bell. Doesn't the car run without the A/C oN?

 

[safety_match]

Perhaps one of your fans is not working correctly? And you are only getting the second fan when the A/C is on. Thus it becomes your only cooling.

 

[pcvette]

If I recall, the stock thermostat is a 220 degree. The fan relay only turns on at 235 degrees. This is "Hot" compared to other cars that open at 180-190 degrees, but the C4 was designed this way.

If your sure there is no debris blocking airflow, switch out the thermostat to a 180, give it a thorough flush (the radiator holds a lot of crud on the bottom when I did mine) and you should notice a difference.

 

[rrhayden]

When you say it runs hot, please explain what tempeture you feel is normal and what you see with the4 ac off. It is normal to run 190 to 220 with the vehicle traveling 30+ mph. At that speed the forward motion is forcing air through the radiator and is less relient on the cooling fan.

best of luck

 

[pcvette]

The summer here in Houston Texas, the climate is usually high 90's, low 100s (Heat Index yesterday got to 107!!!)

City cruising around 30-35 mph for me use to run about 205-210. If I was stuck in traffic, my 2nd fan kicked in around 235 and drops the temp back to 205-210. If I was driving on the highway (55+ mph), my coupe usually ran 200-205.

I flushed my radiator, changed hoses and to 185 thermostat about 2 years ago. It runs about 5 degrees cooler than it used to.

Never had any cooling problems, however my coupe has developed a pin leak on the passenger side head gasket after 138K miles.

 

[Tuna]

Here's a thought:
Is your air dam complete and undamaged?

If the center section of the air dam is missing or damaged, the air will not flow up into the radiator properly at cruising speeds - leading to an overheat condition.

 

[DC/NH]

Thanks for all the suggestions. I bought the car (94) 2 years back with 21K on it. It is immaculate and no blockage or damage to the air duct.

DC

 

[Edmond]

Thanks for all the suggestions. I bought the car (94) 2 years back with 21K on it. It is immaculate and no blockage or damage to the air duct.

DC

Try a bottle of Water Wetter, that should drop the coolant temperature by a few degrees.

 

[Bonnell]

Edmond,

I have seen your earlier post concerning the use of water wetter. Did you notice a difference?

After I have driven on the interstate for 20 minutes (70-80 mph) and then exit and enter stop and go traffic, my '88 L98 will sometimes reach 235 (the fan turns on at about 230 but it appears that the temp would continue to climb). I turn the A/C off and the temp rapidly drops to around 210-215 or a little lower.

The radiator appears to be clean and the water/coolant mixture seems to be clean and very green. It seems that my car only has one fan.

Any input would be appreciated!

Thanks,

J

 

[madstacker]

My 94 trans am runs cooler with the ac on and it is because it kicks on the fan.