Happened to be almost 90 degrees today so I turned on the air conditioning for the first time this year and noticed that either the engine would surge or the tranny would feel like it was slipping. When I shut the air off the problem went away. I am currently using the Hypertech programmer set at stage 2 boost. I know that will change my air-fuel mixture and timing by changing the ECM settings. Just wondered if anyone thought that could be the problem or if I should have something else checked?? Thanks in advance...

 

It sounds normal to me. When my AC is on, you can hear the compressor kick on and off and you can hear the engine change tones as it does that. I know what you mean by the tranny feeling like it is slipping. Mine is a dog with the AC on. The AC really drags the engine down. On a 100 mile trip, I usually burn maybe a 1/16 of a tank. With the AC on, about an 1/8. Same speed both times and same conditions.

 

Take a look at this thread
Good Luck
https://www.dieseltruckresource.com/...threadid=30544