My A/C, when left on after I cut the the truck off and restart it, sometimes resumes in the defrost mode and then after moving the truck, it will return to the normal mode for Max Air. It will not return to the Max Air mode by just rotating the dial. Please advise.

I would start out checking for vacuum leaks or vacuum line damage. Fairly common.

I would start out checking for vacuum leaks or vacuum line damage. Fairly common.

Yep, start at the vacuum pump and follow the line to see where it is cracked. The vacuum controls ALWAYS 'default' to defrost as a safety measure.

Thanks. I'm traveling and have little or no internet. I found the leak in a connection and should be able to replace the part myself. I used some electrical tape on it and it has worked since. Was relieved to find out it should be a low cost fix as I'm on the road and have experienced some triple digit temps the past few weeks. I will be in Iowa for the next six weeks or so.

I would start out checking for vacuum leaks or vacuum line damage. Fairly common.

Can someone help me identify the part I need to replace. It is the connection on the line that runs from the lower left front side of the engine to the connection on the upper part of the outside firewall located about middle way of the firewall. ~~

Mohok,

You may just want to stop by a "real" parts store. The guys at the box stores won't know. IIRC the tubing is 5/32". You can replace broken parts of the tubing with 5/32" vacuum hose. The older guys will know exactly what will slip on and hold vacuum. This will definitely get you by.

If all else fails, see if there is a Cummins dealer near you. They should have that part. I know they supplied the connection to the vacuum pump, and possibly the next part also.

GL

Hag