97 expedition xlt overheats when the a/c is on

[adammcarthur]

I purchased a 1997 expedition xlt with the 5.4 in it a few months ago and I love it, I was a suburban fan until this expedition fell in my lap for a price I couldn't turn down, but recently its developed an unusual problem.
After a 30 minute drive home on the freeway doing 75 with the a/c on I existed the freeway and the temp shot all the way up past the redline, the moment I shut the a/c off it dropped back down to normal. Now I can't drive with the a/c on without the truck getting very hot, however no a/c runs perfect. Any advice or anyone familiar with this problem? I'm thinking fan clutch or thermostat but not and don't want to throw wasted money and parts at it. any help would be greatly appreciated, it way to hot in the phoenix area to not have the a/c working the wife and kids are melting.

 

[toms89]

I would check the radiator and condenser carefully for any obstructions.

At speed the fan does very little. If its after you slow could be a fan clutch. Shut engine down and try and spin fan by hand. If its hot there should be fair amount of drag and difficult to spin.

Fan clutch would be my first guess based on it only being an issue while the a/c is running.

Water pump, thermostat, air in system are other possible sources with the cooling system.

Replacing the stat is pretty inexpensive. Might consider flushing the system and installing a new stat as part of routine maintenance anyways.

 

[tonydiv]

I agree with Tom. Next time the truck is completely warmed up, turn it off and then give the fan a spin by hand. It shouldn't want to spin. (the clutch engages when it's hot)