2006 Rx400H Weird A/c Issue

[mbradburn]

Lexus can't figure this one out - often the A/C on a hot day will start blowing warm air without warning. Changing any and all A/C settings has no effect. However, if I stop the car, turn the engine off, and then immediately turn the engine on, the A/C works as normal. Usually doing this once will fix the issue for the remainder of the ride -- on occasion I have to do the off/on routine a couple of times. Anyone have any ideas or have run into the same problem?

[RX400h]

Does the AC compressor swtitch off when this happens? That'd be the first thing I'd check if I were a mechanic. Loose ground wires are known to cause erratic behavior such as this.