Heater Hose vacuum - The 1947 - Present Chevrolet & GMC Truck Message Board Network

VanceH · 09-27-2009, 10:11 AM

There is two Vacuum advances on my GMC Jimmy with A/C, the one mounted on the firewall seems to open a vent under the cowl, it seems to be working and then there is one in the middel of one of the heater hoses? Not sure what it does or if it is working, i cant seem to get the vent to close under the cowl and it blows warm are inside the cab, not a bad thing this winter but its still hot around here??

JimKshortstep4x4 · 09-27-2009, 12:07 PM

The vacuum valve on the heater hose shuts the hot water flow off when the AC is on. Depending on the year of your truck the valve could open with vacuum applied or it could close with vacuum applied.

Jim

haysonj · 09-27-2009, 12:11 PM

You didn't say if you have ac or not but the vac pots open and close the fresh air and coolant valves they are controlled by a valve on your dash levers

VanceH · 09-27-2009, 12:58 PM

Ok, i understand some what, i do have A/C but its not all there, the compersor is gone, but when i turn it to ac, i still get hot air, i can see the vent in the cowl and it seems to be working with the vacuum on the firewall, what makes the heater hose valve close? Should it close when i switch it to A/C??? Cause it doesnt

haysonj · 09-27-2009, 01:10 PM

Quote:

Originally Posted by VanceH

Ok, i understand some what, i do have A/C but its not all there, the compersor is gone, but when i turn it to ac, i still get hot air, i can see the vent in the cowl and it seems to be working with the vacuum on the firewall, what makes the heater hose valve close? Should it close when i switch it to A/C??? Cause it doesnt

The heat valve should be closed all the time and only open when you turn the lever to heat. Your valve may be froze and would have to be replaced. Pull the hose off turn on the heat and check to see if you have vac at the valve.

Wrenchbender Ret · 09-27-2009, 04:17 PM

Some water valves only shut off when the control is on max. or recirculate.

ChevLoRay · 09-27-2009, 04:23 PM

Go to NAPA or any other auto parts store and get a valve that fits in-line in a heater hose and you have the priveledge of turning the knob yourself to open/close it as you need. Doesn't require vacuum. Doesn't care if you controller works anything, or not. If you need heat, and the valve is closed, open it. Vice-Versa if you don't need heat and the valve is open. Worst thing that happens to them is the stem of the valve may leak after several years. If it does, fix it or replace it. Your option.

09-27-2009, 10:11 AM	#1
VanceH Loving the Jimmster Join Date: Jun 2008 Location: Emmett, idaho Posts: 575	Heater Hose vacuum There is two Vacuum advances on my GMC Jimmy with A/C, the one mounted on the firewall seems to open a vent under the cowl, it seems to be working and then there is one in the middel of one of the heater hoses? Not sure what it does or if it is working, i cant seem to get the vent to close under the cowl and it blows warm are inside the cab, not a bad thing this winter but its still hot around here??

09-27-2009, 12:07 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Heater Hose vacuum The vacuum valve on the heater hose shuts the hot water flow off when the AC is on. Depending on the year of your truck the valve could open with vacuum applied or it could close with vacuum applied. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

09-27-2009, 12:11 PM	#3
haysonj Registered User Join Date: Dec 2007 Location: Santa Maria, Ca. Posts: 1,423	Re: Heater Hose vacuum You didn't say if you have ac or not but the vac pots open and close the fresh air and coolant valves they are controlled by a valve on your dash levers Attached Images __________________ 69 Chevy 4x4 383 Power

09-27-2009, 12:58 PM	#4
VanceH Loving the Jimmster Join Date: Jun 2008 Location: Emmett, idaho Posts: 575	Re: Heater Hose vacuum Ok, i understand some what, i do have A/C but its not all there, the compersor is gone, but when i turn it to ac, i still get hot air, i can see the vent in the cowl and it seems to be working with the vacuum on the firewall, what makes the heater hose valve close? Should it close when i switch it to A/C??? Cause it doesnt

09-27-2009, 04:17 PM	#6
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,223	Re: Heater Hose vacuum Some water valves only shut off when the control is on max. or recirculate.

09-27-2009, 04:23 PM	#7
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Heater Hose vacuum Go to NAPA or any other auto parts store and get a valve that fits in-line in a heater hose and you have the priveledge of turning the knob yourself to open/close it as you need. Doesn't require vacuum. Doesn't care if you controller works anything, or not. If you need heat, and the valve is closed, open it. Vice-Versa if you don't need heat and the valve is open. Worst thing that happens to them is the stem of the valve may leak after several years. If it does, fix it or replace it. Your option. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.



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