A/C clutch cycles rapidly on and off

[detsgtdavis]

First I want to say hi to everyone. Now to my question.

98 Explorer XLT V8 180,000 miles

Truck idles in N ~800-1200 rpms
Truck idles in G ~500-700 rpms while pressing brakes

About a month ago I noticed that while waiting for traffic lights to change my rpms would surge (between 500-800). Once I let off the brakes and increased the rpms I don't notice any surge. I noticed that when the truck is in grear and at idle my a/c clutch is kicking on and off. It will stop once I put the truck in N or P. Now this problem does not always occur. I can crank the truck with the climate control knob set to defrost or ac and drive it with not problems. But then if I swith the control knob the problems then starts. Other times I don't have to do anything other then drive it and it will start cycling on and off.

I checked the coolant level on the low port side and had to add a can. I used the cheap guage from Autozone so I don't know what the high port side is.

Does anyone have any suggestions on what to check next?

Thanks!
Bill

 

[detsgtdavis]

When I left work today I notice the surge is there even in N or P. Its just isn't that noticiable because of the higher rpms.

The surge is happening when the motor is under a load (compressor clutch engages). It really acts like the idle advance (not right term) is not adjusting each time the clutch engages.

Sorry just thinking (typing) out loud.