Overheats w/ A/C on

[Tim]

Went on a long trip the other day, and the temp gauge would go to 1/2 way, then back down, and stay somewhere between half and cold. But on the way back, I was driving at about 60 and the needle hovered at the 1/2 mark, and when I slowed down because of traffic the engine overheated. I have a working fan and thermostat so the problem doesn't lie there.

Any ideas why the engine would overheat? I've never had this problem before with A/C, even in really slow traffic.

This also brought to light one drawback of plugging the heater core: You can't turn on the heat to cool the engine down.



Regards,

Tim

[qaking]

Tim, give me some more symptoms:
Did the temp gage go all the way to the right?
Did the engine shutoff?
Was the cooling fan running?
Did the check engine light come on?
Were you blowing steam from under the hood?

[Tim]

Temp gauge went almost all the way to the right; I pulled over after it went 3/4 of the way.

I don't have a check engine light; the tach cluster is from an '88 which didn't have check engine lights.

The engine didn't shut off.

There was no steam, but the engine was really hot.

The fan was running.



I got off the road when I noticed the temo gauge had gone past 1/2.

Regards,

Tim

[Munner]

Exact same thing happened to me today with my 1990 Festiva. I pulled over when it got to about 3/4 - fan was running and there was plenty of coolant in the rad/overflow.

[batstiva]

Damn, I can't even get mine to the halfway point. :roll:

[bassman]

i have no air but mine did some weird stuff like that so i put in a new thermostat.
no more problems.
in your case i would try a new thermostat and new fluid and maybe a flush.
i know that lots of bugs can plug a rad as i found out the hard way on a road trip to a rock concert in my dads van.
there were lots of bugs but then it was like there was rain and it was bugs .
next thing i know i am at a rest stop with 2 drunk guys and 3 drunk girls and me sober trying to find water.
well an hour later a guy in a van charged me 20 bucks to wash it down .
he was makin big bucks cleaning rads on semi trucks .
turns out it was a wet year and bugs were real bad and plugin up trucks.
keep us posted on what you find

shayne

[Tim]

Good idea.

Funny thing is, I replaced the thermostat a few months ago. So it shouldn't be a problem.

As far as I can see the radiator isn't plugged or anything. I've drained it recently and there's no rust or anything whatsoever in it.

Maybe I should get a radiator from an auto Festiva.



Regards,

Tim

[gomer]

I'd try a new thermostat anyway (removing the thermostat is a big no-no ,, water won't spend enough time in the radiator to lose enough btu's) ... water cools better than anti-freeze ,,, a "water-wetter" additive will get you almost 20 degrees cooler due to better heat transfer from water/coolant to the metal of the radiator (soft water works well too)... on most cars (I don't know about the festy) a 2nd fan relay keeps the fan running anytime the a/c is on ... if you have any doubts about the fan or relays I'd rig a relay to run the fan anytime the motors on and let the thermostat deal with the temp control...

[Tim]

I replaced the thermostat around Christmas; I doubt it's bad but I will check anyway just to be sure.



Regards,

Tim