94 xlt overheats when a/c is on

[GreenMachine2000]

I have changed thermostat,cap, belts are good, water pump replaced prior to my ownership, hoses as well.. Radiator was new 8 months ago...I thoroughly flushed rad/engine- even used clr- not much came out in the way of rust/yuck...No water in oil or vice versa--

Fan blades all have cracks but I've heard thats typical and prob not the prob--
My last guess is fan clutch-
Stays cool when a/c off only heats up (point of boiling over into reservoir)when a/c is on--I live in Vegas so a/c is a must

Does cool down when heat is turned on
i rinsed the rad core externally as well too include a/c core...
Thoughts? Could it be the clutch??

 

[mrdsweet03]

over heating

one way to tell if your fan clutch is bad with with the engine running watch the blades if its turning slow thats a sigh also speed up the engine hold it for about 2 to 5 min the blade slows down that your problem

 

[MrShorty]

The test that I've found most reliable for a bad fan clutch I took from a Mitchell manual:

1) Remove fan clutch so you can access the spring on the front.
2) Disengage the outer end of the spring and rotate spring 1/4 turn CCW. This forces the fan clutch to engage all the time.
3) Reinstall and test drive. If the overheating problem is resolved, then the fan clutch needs replaced. If the overheating problem continues, then the fan clutch is likely not the problem.

 

[Dannyboy]

and for an 15 year old truck and how big of a pain in the @ss it is to change the fan clutch I say go ahead and put a new on on. It looks like the final part to change out.

They make a heavy duty model, it works great for these hot climates. I have been in your situaton before I knew what a fan clutch is and fixed everything only to find out it probably only needed the fan clutch.

 

[Anime]

I would agree with just going ahead and getting a new fan clutch rather than the hassle of messing around.

As cheap as they are, I would also suggest a replacement fan to go on it.


It could also be the A/C compressor. If it's going bad, it could be putting a massive load on the engine, which causes it to overhead from the load. Typically this will cause a lot of belt slippage and wear. The fan clutch going usually causes higher temps, even without an A/C load, especially on hot days in Vegas.

How much or little the belt is worn could help you figure out which is more likely, although it would also depend how old the belt is as well. If the belt is fairly new and looks very shiny on the smooth side or is just incredibly worn, it may be the compressor. If the belt looks to be in really good shape, it's more likely the fan clutch isn't fully engaging.

 

[Explodr94]

My Ex did the same thing and I changed everything like you are doing. Then I saw a post on here that talked about the tranny cooler leaking and gunk building up on the a/c condensor. I looked and had about a quarter inch of sludge blocking the air flow. Pull the grill off your Ex and look at the condensor. If your tranny cooler lines are leaking and a lot of them did you might have this same condition. I cleaned mine with engine degreaser, water, and compressed air. Good luck.

 

[GreenMachine2000]

I have the new clutch and fan

My luck Autozone did not have the tool available- so I bought a large adjustable wrench..I'm going to try and get that thing off- it appears simple- but I have no luck- if it can go wrong- it usually does lol..I hope this cures it. I'm thinking I'll wash the ac condensor down as a preventitive measure anyway..I haven't checked to see if its a mess- it looks ok from the front side...

I'm missing the high side cap on the ac side and saw a little oozing from around the nozzle. I did a recharge on the a/c and think it all but went bye bye perhaps through this high side leak. Hoping a cap will cure it.. I wonder if this contributes to the heating problem..

Serp Belt looks good imo....

BTW Yall are great for taking time to reply- Comraderie rules...

 

[mrdsweet03]

best bet to do for that is replace the valve core cap will slow the leak but wont stop it