The saga continues. I just heard back from my friend Hugh, the service manager at Feldman Imports. It gets trickier...

According to Hugh, who spoke with his Nissan technician, they (Nissan) changed the logic of how the system works on the '03. Regardless of whether or not you have an XE or an SE, this is how the system is SUPPOSED to work:

With the engine running, turning the fan output selector switch to "defrost" or "defrost and foot" mode will activate the compressor and a clutch will kick it in and out as is necessary to keep the air dry and at temperature. IT WILL STAY ENGAGED AS SUCH regardless of how you alter the fan output selector switch OR the A/C switch at this point. So, no matter where you want your air to blow, the compressor will continue to kick in and out regardless of the position of the A/C switch.

The only way to "reset" the system, is to set the fan output switch to "top vent" or "floor vent" ONLY, turn the truck OFF, take the key out of the ignition, and restart the truck with the switch in that position. Then, the A/C switch will operate as it should (unless you flip over to Defrost, where the whole thing starts over again).

I don't know if I'd like it this way or not. If you use the defrost in the morning and forget to switch it to "floor" or something, the compressor will kick in for your entire drive home unless you stop the truck, switch out, and restart.

Weird. Hugh also said that the owners manuals were not changed to reflect this change to the system. He tried 6 trucks on his lot and they ALL worked this way.

If this post is confusing to you (its hard to write up such weird logic), send me an e-mail with your phone number and I'll give you a call so we can discuss it further.