Because my truck likes to get alot of moisture inside (bad weatherstripping letting rainwater in, and a couple other factors), I usually drive with the heat on full and the A/C on to prevent the windows from fogging up. Today I noticed that with the engine warm and idling, a minute or so after switching on the A/C, I'd hear a click like a relay disengaging (or a breaker popping?) and my engine would drop back to normal idle. If I'd wait 3 to 5 minutes and turn it on again, the same thing would happen. Any idea what the cause of this could be?