Hey guys, I currently own a 2005 Dodge ram 1500 4x4 5.7L, and here's my problem. My A/C system seems like it cant make up its mind, most of the time when my heat/cool **** is on full cold it will work full cold(most of the time), but if I move it even a click toward the heat side, it gets cool for about 3-5 seconds, then hot for 3-5 seconds, then cold again, then hot again. It seems like its searching and cant find the temperature. Im in the Air Force and I took it to the auto shop, and they said there might be a hole somewhere in a vacuum line, but i cant find any vacuum lines anywhere. I checked the pressure and it's good and my A/C system is serviced just where it should be. Any help would be appreciated. Thanks guys!

 

The ductwork uses small servo motors, not vacuum to control the blend door and such, I believe. Could be a bad motor or blend door.

 

blend doors have been a problem with your temp problem it's most likeley your temp mode door