First off, thanks to all who contribute to this forum! I thought I'd make my first post something that might help other folks that may have a similar problem...and I think some of you might get a kick out of this particular problem/solution. I haven't been satisfied with the A/C on my '81 since I bought it (original style equipment but converted to R134 by previous owner) so I went through the the system to "redo" the conversion. Drained the compressor, flushed lines, new o-rings, new accumulator and orifice tube, etc. Pulled 30 inches of vacuum for longer than necessary and refilled with appropriate type/volumes of oil and refrigerant. The gauges were spot-on once I was finished but the A/C just didn't blow as cold as it should. I've done a fair amount of conversions before and I understand the limitations of R134 in a system designed for R12 but it just wasn't quite right. The volume of air wasn't great either and I had attributed that to an old blower motor and poorly sealed duct system. Also, the hot/cold lever wouldn't go all the way to hot...felt squishy/spongy when I tried to put it over to hot but it's summer in Houston so who cares... I'll fix the cable later right? I got to work on addressing the duct system and I removed the large duct that exits the heater box behind/beside the glove box and turns up and goes to the the dash ductwork. I found my issue: a mouse mansion in the heater box. This was no ordinary mansion, only the biggest and best for Texas mice...a full on 1 cubic foot fat rat crib at the corner of Evaporator and Heater Core street. The mansion has been temporarily relocated to my garage floor; 15/16 wrench for scale: All of that was in the heater box crammed against the evaporator core and the blend door. No wonder the temp knob was spongy. A/C fixed.