Well, I learned something new today: evidently Defrost does more than just blow warm air onto the windshield, but also runs the AC compressor (presumably to remove moisture from the air). It started a few days ago when I noticed a fluttering/scraping sound occasionally when driving. I opened my hood to find that when the AC compressor is engaged (yes, it is winter here, but the defrost was enabled) the accessory belt was slipping on the main pulley. I imagine it won't be long before the main pulley eats through my accessory belt if I use the AC compressor. I tried rotating the AC compressor by hand and noticed at first (if the car had been off for a few minutes) the compressor rotated freely and easily. If I turned the AC (or defrost) on for a few minutes and tried again the compressor was extremely difficult to rotate by hand. This leads me to two conclusions: 1.) the AC compressor is broken or 2.) there is something jammed in the AC coolant path (kinked tube or something of that sort) that causes tremendous backpressure when operating. Has anyone encountered anything like this before?? The AC compressor is a stock 03 WRX unit (calsonic kansei 73111 FE021). For the time being, I have removed the power cable for the magnetic clutch (the compressor will not engage without this). Thoughts?