I replaced the expansion valve and dryer and recharged the system with R12. It is working perfect. When the control is on full heat, the compressor is on and running. There is cold air being delivered to the back seat vent and hot air to the front vents. When in max cooling mode all vents (center vents excluded, probably bad) deliver cold air. The only pod that I know is good, is the one at the driver side kick panel. It will stay operated with a mighty vac connected to it. I have been looking at the posts concerning w126 vaccuum pods and have not seen anything describing heat and air on at same time. Could this be a climate controller unit problem? I will keep searching the archives. I hope someone can take a short cut to the trouble. Car is a 1989 560sel. Thanks