I gave my 740 to my mother-in-law years ago and I guaranteed it for a couple of years. I put in a new compressor (the Chinese rebuilt compressor from eBay lasted about five weeks ) , a new evaporator which wasn't necessary, and a new condensor. Now she is claiming that the system does its job of chilling the evaporator but that the electrical switch with the snow flakes won't open the doors in the ventilation system and let the air in. She doesn't speak English but claims a mechanic told her this. Those doors are opened by vacuum tubes as I recall. The question is: is there some way of manually opening these doors ? What is the fix on those? HELP! Car in Miami and mother-in-law not happy Thank you in advance