2nd Gen Non-Engine/Transmission A/C warms up at stop lights

[JRS]

Driving down the road my A/C blows 39-40°F out of the center vent with the return switch on. However if I sit at a light for even a short amount of time it will climb all the way up to 55-60°F. I have checked and the anti-freeze is at the proper level and concentration. The engine temp. is running normal while sitting (155-170°F) It started doing this last Spring and I thought it was due to a leaking head gasket. However, the head gasket has been repaired and the problem still exists. I've even checked the engine fan and it seems to still be properly dampened. Also the blades on the fan are clean, so there's been no leaking silicone from the clutch.

 

[TWilkening]

Did you have the pressures in your AC system checked?

 

[NHays]

Mine does that also, I even overcharged the system a little because it was REALLY hot outside and still no change. going to keep an I on this one.

 

[JRS]

Mine just started it this Spring. going to check my pressures again tomorrow. normally I set my system up for 1,000 rpms and put a fan in front of the radiator, but this time will check at idle w/o fan. Mine was cutting out totally after an hour running down the road. found out it was the clutch cycling switch on top of the dryer. Try as I might, I couldn't get a new sensor to thread on the Schrader valve on the dryer. o-ring kept blowing out. My buddy (prof. mechanic) hooked up his Snap-On evac machine, drew some of the pressure off, put the sensor on, and then fed the freon back in it. Still had 40°F center vent going down the road. (recirc on) However, I still had the tepid air at a light.

 

[DBraunig]

That sure sounds like a defective fan clutch. Or a lot of debris/grime in the charge air cooler or radiator restricting the air flow. Check the radiator/cooler for debris and clean out with a pressure washer or compressed air or both (free). If that doesn't correct the problem i would suspect the fan clutch.



Dave.

 

[WestTN]

How's your idle speed? It can drift down on the P7100 pump.

 

[scotmartin]

I vote for the Fan Clutch.

 

[NHays]

I have brand new fan clutch, did not fix mine.

 

[JRS]

how much was a new fan clutch? Mine does not spin freely like one would expect if it was bad.

 

[NHays]

i paid $68 at Napa in Cushing, Oklahoma

 

[jtwcummins]

I had the same issue since my truck was new. Problem could be the fan clutch is weak, but the clutch doesn't fully engage until the coolant temp goes to about 170* and stays there for a time. Then it starts pulling more air. I installed a pusher electric on my truck. Connected to batt thru a relay. Relay picks up with the a/c clutch and moves lots of air thru condenser and helps alot in traffic.



Be careful when replacing the fan clutch. The after market units fit but are not really designed for the diesel. Get from Cummins.

 

[JRS]

Like the idea of the pusher fan, since I have one. relay using the signal from the AC clutch is a good idea. thanks.

 

[EBozard]

what kind of pusher did you use. i have been wanting to do the pusher for a while. i did a second transmission cooler , but also have the ac problem. i know its the fan clutch. i replaced mine with an advance store one but it helped very little. for a test i swapped the one from my other truck, and to my thinking it was the fan clutch. sp ditto on the above, go to cummins, it'll solve your problem. but if you pull alot of weight as i do, you need the extra air.

 

[NHays]

Hmm, looks like I need to go to Cummins for fan clutch. How much are they.

 

[LMcCary]

Fan clutch should be stiff when hot. If not, replace. One draw back, hot is about 170 to 190F degrees. So I install electric fans to solve the AC warm up during idle.