The Ex runs hot with the A/C on

[irtySanchez]

On any normal day (A/C off), the 94 Ex runs just fine. The temp gauge stays between the N and the O on normal and doesn't flucuate at all. But when I turn the A/C on, it rises slowly and goes almost to the L in normal, then bounces back and forth slowly, running relatively hot. Then it starts to idle high. This happens almost every time I turn on the A/C.

Any ideas?

 

[aldive]

Have you had the cooling system flushed and the coolant replaced recently?

 

[DeagleDave]

could be what aldive said.

or you could have clogged radiator, water pump going bad, or your fan and fan clutch could need replacing. mine does something very similar but the needle doesn't bounce back and forth. with a/c off the needle stays in the middle but with it on in the orlando heat it rises to the m or the a but sitting at a light it can go as high as just beyond the L. check this stuff out, a 10 blade fan at ford is around 40 and you can get a fan clutch at the auto parts store for about 30.

 

[Bronco_bill]

The manual that came with my 91 (don't remember the exact words) said that it is normal for the temp to reach the end of NORMAL guage as long as it dosen't go to overheat. You should read it for your self. Alot of people seem to get flucuating temp so you may want to do a search on it but I think everyone decided it dosen't hurt to have a responsive t-stat. I have new engine along with all new cooling parts and still had it. Believe it or not my cure was replacing the hood. I had a major dent and replaced it with one that had insulation on the bottom of it, and haven't had a major flucuation since.

 

[LiKuiD]

mine temp gauge does the same thing...when the a/c is on it usually goes to the L and bounces back to the R and stays in between the two. never had any overheating problems though

 

[jobunn]

A friend of mine had a similar overheating problem with his Explorer, ran hot with a/c on. It turned out to be a bad thermostat, guess it wasn't fully opening or not at all.

 

[irtySanchez]

Well, I replaced all the manifold gaskets a month ago, at which time I also replaced the t-stat. I know that isn't the problem.

Although the Ex doesn't overheat, my real worry is that when this happens, it makes it more difficult for me to brake. Since the engine RPM's are elevated, there is more braking effort needed to stop. This translates to more wear and tear on the Ex.

On a lighter note, replacing the manifold gaskets did solve my pinging problem. I wasn't sure if I even needed to do them. I was just bored and had an idea to do some engine work. I did NOT regret it!!! I recommend it to anyone with the dreaded ping ( which should be about 83% of you).