Ac Control-how Many Vacuum Lines?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MONGO1957 · 05-02-2006, 09:23 PM

Hi Y'all
I Just Rebuilt An Ac Control Unit. I Noticed That One Unit That I Had Has 3 Connectors For The Vacuum Hoses To Connect To.
The Other Unit (a Donor Unit-i Stole The Levers)has 2 Connectors For The Vacuum Lines To Connect To. My 1970 Chevy Shop Manual Shows The 2 Connector Style. Anyone Know How The 3 Connector Style Ac Control Unit Should Have The Vacuum Lines Routed??

Thanks, Mongo1957

stope4 · 05-02-2006, 11:00 PM

you can use either, but on the one with three ports will require that one be blocked off. Correct would be the one with two ports.

MONGO1957 · 05-02-2006, 11:10 PM

Thanks Stope4-i'll Block Off The Third Port

JimKshortstep4x4 · 05-03-2006, 05:18 AM

Here is the vacuum diagram for the three port vacuum switch.

Jim

stope4 · 05-03-2006, 10:15 PM

Jim, what is the specific year and vehicle for the diagram you show.

JimKshortstep4x4 · 05-09-2006, 08:16 AM

The schematic was in my Assembly Manual for the 67-72 trucks and there was no mention of the year. The (5) trucks, (70-72) that we have with AC have the two port control so my assumption is that the three port controls are from the 67-69 years. It could just be a difference in the assembly plants.

You may want to pose the question in a post!

JIm

badpeanut · 05-09-2006, 01:47 PM

My '72 had the two port control. The replacement has three ports, but I haven't installed it, yet.

05-02-2006, 09:23 PM	#1
MONGO1957 Junior Member Join Date: Feb 2004 Location: WORTHINGTON,OHIO 43085 Posts: 26	Ac Control-how Many Vacuum Lines?? Hi Y'all I Just Rebuilt An Ac Control Unit. I Noticed That One Unit That I Had Has 3 Connectors For The Vacuum Hoses To Connect To. The Other Unit (a Donor Unit-i Stole The Levers)has 2 Connectors For The Vacuum Lines To Connect To. My 1970 Chevy Shop Manual Shows The 2 Connector Style. Anyone Know How The 3 Connector Style Ac Control Unit Should Have The Vacuum Lines Routed?? Thanks, Mongo1957

05-02-2006, 11:00 PM	#2
stope4 Registered User Join Date: Jan 2006 Location: Houston Posts: 434	Re: Ac Control-how Many Vacuum Lines?? you can use either, but on the one with three ports will require that one be blocked off. Correct would be the one with two ports.

05-02-2006, 11:10 PM	#3
MONGO1957 Junior Member Join Date: Feb 2004 Location: WORTHINGTON,OHIO 43085 Posts: 26	Re: Ac Control-how Many Vacuum Lines?? Thanks Stope4-i'll Block Off The Third Port

05-03-2006, 05:18 AM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Ac Control-how Many Vacuum Lines?? Here is the vacuum diagram for the three port vacuum switch. Jim Attached Images

05-03-2006, 10:15 PM	#5
stope4 Registered User Join Date: Jan 2006 Location: Houston Posts: 434	Re: Ac Control-how Many Vacuum Lines?? Jim, what is the specific year and vehicle for the diagram you show.

05-09-2006, 08:16 AM	#6
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Ac Control-how Many Vacuum Lines?? The schematic was in my Assembly Manual for the 67-72 trucks and there was no mention of the year. The (5) trucks, (70-72) that we have with AC have the two port control so my assumption is that the three port controls are from the 67-69 years. It could just be a difference in the assembly plants. You may want to pose the question in a post! JIm

05-09-2006, 01:47 PM	#7
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,756	Re: Ac Control-how Many Vacuum Lines?? My '72 had the two port control. The replacement has three ports, but I haven't installed it, yet. __________________ '05 Chevy 2500HD 4x4 '72 GMC LWB 4x2 driver '72 Chevy LWB 4x4 plow truck '71 Blazer 4x4 driver '70 GMC LWB trailer

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