Hello Everyone - Long time reader, first time poster.

I’ve had my truck now for a year and finally fixed the A/C. Now that it works, I can’t run the A/C without the engine overheating. (Over the ¾ mark) I replaced the thermostat with an 180F, which I bought from Cummins, and it still runs hot. (Over the ¾ mark) I had flushed the cooling system about six months ago and cleaned the radiator.

I was wondering if the radiator was not getting enough air because of the huge intercooler being in front of everything. A friend of mine had suggested replacing the fan clutch. Since his suggestion I recall the fan always spinning at the same speed whether at a 20 degree start-up or on the hottest day of the year after running all day.

Any suggestions would be very helpful –

Joe

 

I just replaced my fan clutch a couple of day's ogo. now the truck does'nt get over the quarter mark on the guage. If you are not hearing the fan get real loud around the high side of the quarter mark which indicates that it is working then you probably need a new fan clutch.

 

I'm with timb on this one. When I sit in traffic in really hot weather I can hear the fan roaring when I finally get moving again. If you aren't hearing the fan kick in when the engine gets hot, that could very well be the problem. You can't miss the sound when that monster kicks in.

 

do your fans kick in even while going down the highway at 75mph? Mine will kick in especially when going up hill and it brings the temp right back down but you wouldn't think the fan could really move that much more air than your already getting at highway speeds.

 

I have never heard mine on the highway - but I've never used my hitch.

 

Do all the cummins have a clutch fan setup from 89-93? I can never hear mine kicking in....

Jeff

 

Mine will kick in when the temp starts climbing. That is the idea of the clutch
they work when needed and coast when your just out riding around.

If the temp gets up there you should even hear it at any speed, if not I would
replace it.

 

sounds like fanclutch trouble

fill in your signature so well be able to help you more GO IN USER CP TO FILL IT

 

Yeah, but you might never have got it hot enough. Mine will only run when I have to sit in traffic on days in the mid 90's with the A/C on. You can't hear it at idle, but I know it's on because the idle speed drops a little more. It only runs until I'm about halfway through 3rd gear once traffic moves again - it is really effective.

 

Sounds like the fan clutch to me.
You should also be able to feel it kick in.
Does anyone have a figure as to how much horsepower this thing consumes?

Just a little tidbit... I used to have a 1975 suburban and I was going over Cajon pass in California pulling a trailer. Anyhow it kept getting hot and I figured the fan clutch was slipping but it was over 100* and I had the AC on and I should have switched it OFF but oh well...
Because the AC was on and the fan was not pulling enough air trough the condenser, the high side on the compressor must have spiked 400 PSI because it fried the compressor and finally ruptured the high side line.
When I pulled over, the case on the compressor was smoking it was so hot.
BTW you haven't removed the fan shroud have you?
Jim.

 

Now here about a month ago mine was getting hot when pulling hills with the trailer in tow. when I went down the other side it would cool right down. now even though the clutch fan was bad and I didnt know it, I had the radiator rodded out. it was plugged pretty good with calcium deposits that flushing would not take out. now with the clean radiator and the new fan clutch, the old girl will not get to the quarter mark on the guage even on the hottest day's. so you might even think about a good cleaning.

 

I ordered the clutch, and should have it this afternoon. Haven’t started the install yet. The fan shroud is still on. From what everyone is describing, it seems like the fan was never working properly. I’ll take your advice and give it a good cleaning, I want her to run nice and cool.

Thanks Everyone!! I’ll let you know how it turns out.

 

Mine's running hot too.... but its from a very poruse (sp) radiator and low coolant level

 

If you've never taken one of these clutches off it can be a pita. I use a 1 7/16 end wrench on the fan nut, and then hit the wrench with a ball peen hammer real hard to break it loose. sometimes it takes a few whacks but it does the job real well. and the fan nut is left hand thread. that means hitting the wrench towards the batteryto loosen it. good luck and I hope this works for ya.

 

Completed the install. Removing the fan nut wasn't easy, but wasen't as hard as i had thought. Running much cooler now, just at the half mark. Thanks all for the tips!!