Buick Repair Questions? Ask a Mechanic for Answers ASAP
Hello, Thats because the system defaults to defrost when the vaccuum supply source is not present at the AC Heater control switch.
You need to look for a vacuum line coming from the engine--thru the firewall--to the control unit. It has a vacuum reservoir that holds vacuum and then sends it to the control. This is a VERY easy repair once you find the hose that is disconnected or broken.
Nope...thats just for the electrical acuators for the contrls inside the AC/Heater case.
Its easire to explain if i can call ya?