Do have them check if the dash knob for the air is working. Mine was stuck open for heat even though the knob could be turned to air but it wouldn't activate it. Some times it would activate the air and some times not.
It runs off a vacuum and it is a very common problem for that to go out. Albeit its not a cheap repair though. The darn thing like most now its an assembly and it's buried deep under the dash. Labor intensive costs.
When I found out what they wanted to fix the assembly I waited for the knob to work on air and did not touch it again. Figured I was going to Florida so didn't need no stinkin heat to work. :B