W84DBOOST

I looked through the posts but didn't find the issue I'm having. The A/C on my 05 Cummins blows cold as I drive, but as soon as you stop the A/C clutch cycles on/off, and the air blows warm. I took it in, and the A/C guy vacuumed and refilled. It was a little less than a half of a pound of freon short. That took care of the temp difference between pass & driver vents, but it did not fix the problem, so he then says I need a new compressor and orifice tube, but that doesn't make sense to me. If it blows cold while I'm driving I assume the compressor works OK. I hate to throw parts at it just to see if it works, and the shop is just interested in replacing parts, at my expense. Is there a switch or sensor that I should look for that may be causing my dilemma? Thank You in advance.

05 CTD2500

High side pressure could be reaching 500-600 psi which cuts off the compressor, then it kicks back in once pressure comes back down. The orifice tube could actually help its an updated part that has a larger opening, or the old one could be clogged maybe. A pusher fan on the front of the condensor is what seems to be working very well for some. Also could be that the fan drive is not working correctly. On my 05 the fan will cycle on and off with the a/c running, I don't know if its due to engine heat or the high side pressure reading but the a/c stays fairly cold even at idle even though the compressor is cycling.

W84DBOOST

I have noticed the temp guage higher at times. I will check the fan first.

Lightman46

You can check to see if it is cutting out on high pressure from lack of air flow across the condenser by running water on the condenser coil when it is setting idling. If you run water on it and it keeps working then you will know it is a air flow problem. If it is cooling when driving down the road there is nothing wrong with the compressor or the orifice tube. You relly need to have a set of A/C gauges hooked up to it so you can see what it is doing to read the pressures

W84DBOOST

Great advice! The cycling stopped as soon as I started running the cool water on the condenser, and started about 5 min after I stopped running the water. I can also stop the fan with my hand while it's running at idle and 220°. I called around and nobody has the non-electric fan clutch. Is that going to be a dealer item?
Thanks

C Schomer

Did they do away with the elec. fan clutch on the 05? I was wondering if I could put a plain, old fan clutch on mine. Do you have a manual trans? I put 2 - 12" fans behind the intercooler, pulling air thru the cond coil and it works great. Craig

W84DBOOST

I believe this is a factory viscous fan. No wires. I have an 05 2500QC SB Laramie 610/Auto 3.73

Jim O

Are you sure that there are not any wires coming up from the bottom.I have a buddy with an 05 and it is exactly the same as my 03 with a wire harness coming up from the bottom. I know this for sure as I helped him install a Jacobs exhaust brake and we had to replace the serpintine belt.
Jim O

C Schomer

Yeh, the wires are nearly impossible to see from above but I got a good look at them yesterday while replacing my belt. Craig

W84DBOOST

I'll check again

W84DBOOST

Looks like you were right. Ordered #55056990AC

05 CTD2500

There is a test the dealer can do with a DRBIII tool that will turn on the fan and check the fan RPM to verify it is almost the same as the engine RPM. Also, IIRC my service manual says to spin the fan by hand with the engine cold and it should not turn more than five revolutions. Lastly there should be a code set, do the key on/off 3 times (leave it on 3rd time) and it should be displayed in the odometer display.

Hunter11

I have an 05 and it does have the wires going to the fan.

W84DBOOST

OK. Thanks for all the help guys. I tested the fan clutch before I took it off and it was not engaging. I replaced with 55056990AC from dealer ($287.00) It works perfectly again. I appreciate all the input, Thanks again!