A/c Clutch taking a long time to kick in
I have a 2004 F350 XL, 6.0, six speed, 4 door, long bed, single rear wheel, air conditioned without climate control that the driver complaint was that it took as much as 40 minutes for the cab to cool off. I started the engine and turned on the a/c and the clutch did not engage. I checked the line pressure and it was at 80 psi. I checked all of the fuses and all are good. The clutch cycling switch checks good. After the truck had run about 15 minutes the a/c clutch engaged. Nobody was near the truck, I heard the compressor engage while I was reading the owners manual double checking fuse locations. At that point the a/c began to work properly, cold air out of the vents, low side pressure at 42, and high side pressure at 225. I let the truck run long enough for the clutch to cycle a couple of times to see if it was a clutch that was just having a hard time engaging. The clutch cycles just like it is supposed to. If I shut the engine down and restart the scenario starts all over again. My next step is to check the voltage at the clutch coil to see if it gets voltage immediately or if the voltage is delayed. Any ideas?