95 F150 overheats with AC on

Your radiator may be partially clogged.

Are you sure your radiator fan is working? If not, this would mostly be a problem when sitting in traffic, especially with the A/C on.

If it only heats at low speed and does as it should when cruising regardless of load, it is probably the fan clutch. You should use the same type as the original. I do not recall if a special tool is need to change that one. If you cannot hear the roar of the fan increase as it comes off idle when it is heating at low speed, this is more likely the culprit.

It's normal for the engine to run hotter when air flow through the radiator is low. I have the same engine and had similar worry, so I intalled a real temp gauge. My temp under those conditions maxed at

230=B0. Normal temp is about 207=B0. When coolant temp gets around 260=B0 is when to worry.

Some things to consider: check your computer for any codes dealing with the cooling system. You said you changed the stat and installed new anti-freeze at a 50/50 rate. That's good. I'd also put on a new radiator cap! Cheap insurance! The rad cap has a lot to do with cooling system performance and for $5, it's a good 'spend'.

I'd also get a hose and using a hard spray, clean off the ac condensor and the radiator behind it. Road junk will cover/coat the fins/tubes with dirt/etc. Keeping the condensor and radiator fins/tubes clean is a good thing to do. Better cooling efficiency with clean parts.

A good thing to install the next time you change anti-freeze is a back-flush valve. Prestone makes it. It's about $10 and an easy intallation. With it, you can flush the cooling system opposite of the normal flow of the coolant. I put one on years ago and it's been a good spend also. Use a good 'flush' cleaning fluid and then back-flush.

Hope some of this helps!

Dave S(Texas)

PS: please don't add this email addy to a pc address book....Thanks! I appreciate it!

||anti-freeze at a 50/50 rate. That's good. I'd also put on a new ||radiator cap! Cheap insurance! The rad cap has a lot to do with ||cooling system performance and for $5, it's a good 'spend'.

Agreed. And get a good brand. Only good brand I know of is Stant.

||I'd also get a hose and using a hard spray, clean off the ac condensor ||and the radiator behind it. Road junk will cover/coat the fins/tubes ||with dirt/etc. Keeping the condensor and radiator fins/tubes clean is a ||good thing to do. Better cooling efficiency with clean parts.

A lot of leaves and grass invariably gets trapped between the back of the condenser and the front of the radiator. No good way to get it out without loosening one or the other, but it's worth doing.

||A good thing to install the next time you change anti-freeze is a ||back-flush valve. Prestone makes it. It's about $10 and an easy ||intallation. With it, you can flush the cooling system opposite of the ||normal flow of the coolant. I put one on years ago and it's been a good ||spend also. Use a good 'flush' cleaning fluid and then back-flush.

I agree - Prestone Flush & Fill Kit.

A quick check of the fan clutch: With the motor hot, shut it down, open the hood. See how hard it is to turn the fan blade. You should feel enough resistance that you can't flip a blade and have it rotate more than a blade or two. Also, be sure your replacement fan clutch is the type with a thermostatic coil on the front center. The parts guys will call this a "Thermal" fan clutch, which is what came on the vehicle. Texas Parts Guy

I agree; the fan clutch has quit. They all quit after a while, and nobody notices until they're stuck in traffic with the A/C on. Partially clogged radiator's not a bad guess either.

thanks for all the advise, i'll check the fan clutch and i didn't know the radiator cap affect temps, I'll change that also

the fan does run, but i guess if the clutch was bad, then it would not turn the proper speed... correct?

haven't flushed my radiator in probably 3 years, i just drain and fill, guess I should do that also

i did power wash my rad fins @ the car wash when i first noticed the truck getting hot like this, but it didn't seem help any

also, check engine light doesn't come on, would i still pull a code if it's not on?

thanks again

||> ||radiator cap! Cheap insurance! The rad cap has a lot to do with ||> ||cooling system performance and for $5, it's a good 'spend'. ||> ||> Agreed. And get a good brand. Only good brand I know of is Stant.

Update: Our salespeople tell us Stant quality has take a downturn in recent years. We are evaluating alternatives. ||the fan does run, but i guess if the clutch was bad, then it would not ||turn the proper speed... correct?

It will appear to, but in fact it is slipping and running at less than engine speed. Again, get it hot, turn it off, and then see how easy it is to rotate the fan by hand. You should feel a pretty stiff resistance. If your tried to spin it quickly, it would stop immediately when your hand pressure stops.

||haven't flushed my radiator in probably 3 years, i just drain and ||fill, guess I should do that also

Don't just drain and fill, reverse flush it with solvent and a Prestone kit. That is the only way you can get the slime and scale off the walls of the cooling passages and the radiator tubes.

||i did power wash my rad fins @ the car wash when i first noticed the ||truck getting hot like this, but it didn't seem help any

Remember, if there is stuff between the rad and the A/C condenser, it's trapped. You can't drive it out with water pressure, it's not water-soluble. If that is your problem, you (usually( have to separate the radiator from it's mounts and move it back for access. You can usually do this with the hoses attached, unless they are hard and brittle, in which case they should come off for replacement.

||also, check engine light doesn't come on, would i still pull a code if ||it's not on?

You would smell the motor cooking by the time the CEL came on from overtemp. Your problem is not critical ...yet. Texas Parts Guy

My parts store guy made a similar mention and now carries the CST brand. Made in America! I replaced my 5yr old Stant with a new CST. :)

Dave S(Texas)

My advice on fan clutches is, always get a quality clutch. Not one at Checker or Auto Zone. I always buy my truck clutches at the dealer. There IS a difference.

Neil