what is this?

[rewardedgamer]

ok so i was looking over my cab and i found this on the bottom in front of the door where you put your feet and have no idea what it is so if someone could help me that would be awesome... also its only on the passenger side

[81_Chevy]

its a vacuum canister hooked up with the A/C. when you flip your switch to A/C that opens up the vent behind it, since that's the intake for the system.

[rewardedgamer]

ok thanks solved my curiosity

[pholliday1]

81 r u sure? I always thought that was just the vent control module( vacuum operated) and there is a return spring that needs to be hooked up can't tell from pict if its connected?

[bd]

The image is of the recirulation door vacuum actuator.  The recirc door is paired with the plenum door located inside the cowl.  The recirc door is normally closed and the plenum door is normally open allowing the entry of outside air into the cab through the heater/evaporator housing.  When selecting "Max A/C," the plenum door closes and the recirc door opens to recirculate cabin air.

Edit:  door operation

[pedigo78]

is there an actual diagram for this system? I would like to see it

[bd]

is there an actual diagram for this system? I would like to see it

Look in the A/C & Heating section of the appropriate year 1973-87(91) GM Pickup Manuals in our Technical Pages.

[rewardedgamer]

The image is of the recirulation door vacuum actuator.  The recirc door is paired with the plenum door located inside the cowl.  The recirc door is normally closed and the plenum door is normally open allowing the entry of outside air into the cab.  When selecting "Max A/C," the plenum door closes and the recirc door opens to recirculate cabin air.

Edit:  door operation

well my air conditioner isnt hooked up and i dont have Freon and that spring isnt hooked up so do i need to hook it up for heat tho?

[bd]

The image is of the recirulation door vacuum actuator.  The recirc door is paired with the plenum door located inside the cowl.  The recirc door is normally closed and the plenum door is normally open allowing the entry of outside air into the cab.  When selecting "Max A/C," the plenum door closes and the recirc door opens to recirculate cabin air.

well my air conditioner isnt hooked up and i dont have Freon and that spring isnt hooked up so do i need to hook it up for heat tho?

Hook up the spring (or wire it closed) and leave the door in place or you'll have outside air blowing into the cab year round.  Could get mighty cold during the Winter.

[rewardedgamer]

The image is of the recirulation door vacuum actuator.  The recirc door is paired with the plenum door located inside the cowl.  The recirc door is normally closed and the plenum door is normally open allowing the entry of outside air into the cab.  When selecting "Max A/C," the plenum door closes and the recirc door opens to recirculate cabin air.

well my air conditioner isnt hooked up and i dont have Freon and that spring isnt hooked up so do i need to hook it up for heat tho?

Hook up the spring (or wire it closed) and leave the door in place or you'll have outside air blowing into the cab year round.  Could get mighty cold during the Winter.

well i dont think air comes in the cab now when i have the windows shut and plus i dont feel air coming in the vents when im driving so maybe the guy before me wired it shut

[pholliday1]

Thanks for the clarity BD!