A/c Clutch taking a long time to kick in

[texasrainman]

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?

[Deereman39]

There is a small gray plastic tube that plugs in to a vacumn control about the center of the heater hoses and it comes out or the rubber elbow cracks causing no vacumn to the heater controls.
Ed

[texasrainman]

I will check that next time the truck is here for service. However, the dash controls appear to be working properly and the vacuum motor on the fenderwell is not running constantly. All of the controls appear to working correctly, it just take about 10 minutes for the a/c clutch to kick in the first time. Once the a/c clutch kicks in the a/c works just as it is supposed to until the truck is shut down and restarted.

[texasrainman]

any other ideas?

[MrJohnWayne]

does the a/c clutch use a relay? If so I would check that.

[texasrainman]

Originally Posted by MrJohnWayne

does the a/c clutch use a relay? If so I would check that.

Yes the clutch uses a relay. I have checked that, I even replaced it with a known good relay and that had no effect on the symptoms.

[jfines@cox.net]

Have you checked the air gap on the clutch? If it is too big then in my not engage.

[texasrainman]

Originally Posted by jfines@cox.net

Have you checked the air gap on the clutch? If it is too big then in my not engage.

Yes I have checked the air gap on the clutch. The problem is that there is no power going to the clutch coil. I have traced the power issue all the way back to the relay. The 12v trigger for the relay is not getting energized after the ignition switch has been turned on for several minutes. It acts like there is a built in delay so the A/C will not be energized during start up. I have noticed that all of my trucks have a delay of several seconds on the A/C after start up. This truck though the delay has gone to several minutes, as much as 15 minutes. It only does this if the ignition switch has been turned off and back on. If I leave the truck running but turn the A/C off and back on, the A/C will operate as it is supposed to.
I guess my next step is to buy a factory service manual with a wiring diagram to see what all has to happen for the A/C to operate.