KDV

Factory A/C '72 Cutlass Supreme - no actual A/C anymore

I've got air blowing through the floor heater and the defroster but not through the dash vents.

Vacuum canister on the firewall's hooked up.

Any clues as to where I should start investigating?

MDchanic

Make sure that the vacuum canister isn't leaking and that you actually have vacuum going into the system.

After that, look at the mode door, diaphragm, and hoses for the A/C, and also at the A/C selector valve.

- Eric

oldspackrat

This may sound dumb, but start the car, turn the radio & fan off & stick you head under the dash near the heater outlet. You might be able to hear a vacuum leak somewhere? Also, slide the mode leverthrough each position & listen for a leak in any one of them?

KDV

Thanks for the help!

tfatboy

Mine did the same thing. Turned out my a/c hoses had desinigrated behind the dash

KDV

Thanks for the input!

I'll start digging into this right after the National Street Rods the first weekend of August.

I've got my fingers crossed that I'll finish the front end rebuild before then.

I'm a little apprehensive about pulling the dash apart without breaking anything. Doh!

tfatboy

No doubt! Maybe you can reach up in there without taking the dash all apart. I just happened to be having my dash pad redone when I saw those hoses all brittle and falling apart

KDV

Got really lucky with this little problem.

The 1/8" vac line coming off the canister was perforated in the engine compartment right before it goes through the firewall.

All the lines under the dash and the diaphragm for the vent door look relatively new.