i was wanting to see if this is normal or not. its an 07 5.9L with 26xxx miles. when i start the truck and the A/C clutch kicks in, its like the engine misfires or skips. it mostly does it the first start of the day, or sometimes when the truck is restarted. the pressure are fine and the clutch cycles fine. the A/C system works fine, blows cold. i just dont have anything to compare it too, to see how hard another one cycles on and off. i hope the compressor its trying to lock up. i havnt pulled the system down yet. but i was thinking it might be over charged on oil. has anyone had this problem, or heard of them being over charged on oil from the factory? thanks

 

It is fairly common to hear a good thud on first engagement of the compressor on these rigs. It will also sometimes cause the engine on mine to change sound for a split second. The computer kicks the idle ever so slightly to compensate for the load of the compressor coming on line. What is funny, is last year my compressor clutch failed and was not engaging, but the ecm still blipped the throttle for the compressor load.

 

The clutch is metal to metal. The reason for the clunk is because rust wears some grooves in it, and the metal to metal contact makes the noise.

Nothing to worry about.

To make it quieter pull the front of the clutch hub and remove the rust. Then dont drive in rain, lol

Carey