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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: 123 pugsy on June 20, 2011, 05:53:19 pm

Title: Vacuum Actuators
Post by: 123 pugsy on June 20, 2011, 05:53:19 pm

I finally got my a/c back together after the evaporator explosion.  ::)

I have hi speed airflow only at the NORMAL setting.

On MAX AC it wasn't drawing cabin air.
I take it it pulls from the flap at the passenger kick panel?
Should this door be open on MAX AC?
Do all actuators ''pull'' when vacuum is applied or do some of them ''push''?
The actuator in this position has the orange line hooked up and pulls closed on MAX AC.

Is it possible I mixed them up when I rebuilt my truck?

Thanks for any help.

Pugsy

Title: Re: Vacuum Actuators
Post by: zieg85 on June 20, 2011, 06:00:55 pm

It should be closed on Max, sorry I don't remember if vacuum closes it or keeps it closed.  Best to reach the line and remove it and see what happens...

Title: Re: Vacuum Actuators
Post by: 123 pugsy on June 20, 2011, 06:17:33 pm

How does the system pick up cabin air then?

Title: Re: Vacuum Actuators
Post by: 1979C20 on June 21, 2011, 03:55:21 am

I believe the air Recirculates on max AC, but I'm not completely sure.

Title: Re: Vacuum Actuators
Post by: 123 pugsy on June 21, 2011, 05:09:06 am

Quote from: 1979C20 on June 21, 2011, 03:55:21 am

I believe the air Recirculates on max AC, but I'm not completely sure.

This is correct.

The problem I have is the vacuum signal at the passenger side blend door is pulling it closed. This signal only comes at MAX AC. MAX AC is supposed to recirculate cabin air and I believe the passenger side kick panel flap is where its supposed to enter to the blower.

Title: Re: Vacuum Actuators
Post by: zieg85 on June 21, 2011, 06:08:43 am

There is another door that is supposed to be open when on Max to recirculate the cabin air. 

Title: Re: Vacuum Actuators
Post by: 123 pugsy on June 21, 2011, 02:59:01 pm

OK, I've confirmed that the vacuum is supposed to pull the flap open rather than closed as was occuring in my truck.

If I wasn't such a conehead when I put it together, I may have noticed the flap was behind the little built in stop so when vacuum was applied, it was actually closing it.

I also discovered I was missing a return spring to pull the flap closed in all positions except MAX AC.

The kick panel flap is indeed the cabin air in as in the photo I posted.