A/C clutch will only engage after 10 miles

[Bilbo]

I have a 2003 Ford Ranger xlt 3.0 flex. The a/c clutch will only engage after about driving 10 miles or so. When it does come on, it's cold. Readings are - running @ 1200 rpm - ambient temp 85 -. Low side is 40 psi - high side is 250 psi. When I shut the engine off the low side slowly increases to 95 psi and the high side decreases to 100 psi. Why does it take so long for the clutch to finally engage? Thanks in advance.

 

[Rick]

I would start by checking the voltage going to the compressor clutch. If it's getting full voltage instantly my guess is the clutch is going bad.

 

[Bilbo]

Rick,
Took your suggestion. No signal is coming to the compressor. Checked the relay - good, jumped the low and high pressure sensors - still no signal. The switch inside will initiate the high idle, so I'm guessing that switch is OK. Can get continuity between the neg side of the compressor plug and ground, but nothing between the pos side and any leg of the relay.
If i am on the wrong section to be posting this, please tell me how to do it correctly.
Thanks, Bill