95 Taurus Overheating when A/C on

[muskyfins]

Originally Posted by shorod

Are you sure the engine coolant is actually getting hot and cooling as rapidly as the gauge would indicate? Maybe there is an engine ground cable or something that is disconnected, causing the gauge to perceive an inaccurate reading from the coolant temperature reading from the sending unit. Have you ever replaced the water pump to make sure the fins on it are fine? Maybe they are corroded just enough that the added load from the A/C cause the coolant to get hot. How about the pressure cap, is it properly pressurizing the cooling system?

-Rod

Rod,

Thanks for your help. I suppose I should clarify a few things-I have a '99 not actually a '95, but this is the weirdest thing I have ever seen. I dabbled as a pro mechanic for about 2 years and have been a solid "minor league" tech for a long time.

To answer your questions, I replaced the water pump due to seal leakage about 2 years ago which did not affect this issue one way or the other. Several infrared temp readings at different locations on the exterior of the cooling system indicated that the coolant temp was in fact signifigantly fluctuating with a/c on or off. Fan operation was also verified. Pressure and level are correct

I have also replaced, then removed the thermostat to eliminate it as a contributor. Now it takes forever to generate heat in the winter. In the summer it runs just a little on the hot side, but again, no t-stat. Then if you turn on the a/c-it just goes up until it reaches the threshold to shut the a/c itself. A few days ago, it was only about 70 degrees where I live and I tried it out and even at those low ambient temp it still got hot. Lastly, I have cleaned the space between the condenser and the radiator and eliminated any bugs, dust, etc.

The car is just posessed. lol I was hoping this was a common problem and someone out there had some little known fix like overharged ac or anything.

This is driving me crazy.......

[shorod]

Have you tried letting the car idle or running it at 2000 rpms while in park until the radiator cooling fans kick in just to see if the car starts to get in the overly hot zone? Does the recovery tank start to bubble or fill/overflow? Have you pressure tested the cap to make sure the cap is doing its job?

-Rod