I have a 99 2500 diesel, tried to use my A/C the other day and nothing but hot air not cool at all hot air. I looked under the hood and saw the A/C clutch engaging for a second then disengaging over and over. Does anyone know why this is happening?

Scott

 

probably low on freon.

 

Yep, that's it, low charge, it's turning off to protect your compressor from burning up because your oil travels with the freon.