: Climate control (FUBAR) 1978 coupe deville



tripleyellow78cad
03-28-05, 07:10 PM
I have an 1978 coupe deville and my a/c has some major problems
first when i have it on a/c on lo auto or high the air only blows out of the heater vents on the floor, not the a/c vents, the air is ice cold though .
I need to find the problem soon because it gets hotter than hell in the summer here:dammit: .
it first started to only drop to the floor on steep mountain roads but now the air only will blow out of the floor vents
the defroster and heater work properly:confused: :banghead: :wtf:

any help will be apriciated

P.S. fubar means (f#$Ked up beyond all recognition)


thanks

Cadidreamin'
03-28-05, 08:56 PM
Maybe you have a problem with the vacuum lines going to the a/c controls. Also check the check valves sometimes they dont do their job and they will cause what you are describing.

The Ape Man
03-29-05, 10:34 AM
Maybe you have a problem with the vacuum lines going to the a/c controls. Also check the check valves sometimes they dont do their job and they will cause what you are describing.

100% on the money. Check under the hood first to see if you have a good vacuum going through the firewall. Make sure the heater control valve holds vacuum and has no pin holes. There may be a Tee and one way check valve + plastic vacuum canister somewhere. More places to check for leaks. If all OK there: One thing that can make engine vacuum dissappear to the climate control system is the PRNDL vacuum switch on your steering column (under dash very close to firewall). That vac switch sends vacuum to the parking brake release gizmo whenever the vehicle is running and is in any gear other than Park or Neutral. They can develop a leak and since the dash vacuum is Teed into that system it will also mess up your climate control. Quick check is to see if your parking brake releases when you shift out of park.
The parking brake manual release handle on Cadillacs must have been designed by a real sadist. It is nearly impossible to not get your fingers smacked if you have to use it when your automatic release fails.