I had exactly the same peoblem recently. The baffle controlling the air flow t the heater matrix would not close. The problem with mine was the drive that opens and closes it. The actuator (small motor) was turning properly but the splined drive shaft was stripped and slipping within the lever. A new actuator would cost £58 from saab. I drilled through the lever and drive shaft in situ and superglued the broken drill bit into the hole. Effectively securing the drive shaft within the lever. Result cool air. I think the cabin temp sensor is pretty reliable (as long as the fan is working).
I had to remove the glovebox and top of dashboard, speaker grilles and air ducts.
Good luck
Stu
I had to remove the glovebox and top of dashboard, speaker grilles and air ducts.
Good luck
Stu