1990 Mustang 4cyl Hatchback Problem

[hawleyRyder]

I've got a 1990 Mustang 4cyl Hatchback with the following problem, the blower only blows through the defrost and can't switch it from defrost to any other control, i.e. vents, mix, etc.

I've just had a new control module installed and it works, however, the blower still stays on 'defrost'. The module itself is blowing hot and cold as it's supposed to and the fan speeds do work. Is it possible that this might be a vacuum problem?

If anyone has had this problem, I'd appreciate you letting me know.

Thanks in advance.

[Otlaw80]

yes its a vaccuum problem. Find a vacuum line coming from the firewall about where the air box/heater core is. There should be one coming through the fire wall. Follow that one and see if there is any cracks or breaks in the line. If there isn't then check the vacuum tree and the main line that comes off the tree. Usually it goes to a vacuum canister. If you have access to a vacuum gauge and someone that knows how to use it, it will make it easier to find.