![]() |
![]() |
#1 |
Registered User
![]() Join Date: Mar 2014
Location: Luray, VA
Posts: 73
|
Heater Control Valve
My '72 GMC has what appears to be a replacement heater control valve in the engine compartment. However, the vacuum fitting is not connected to anything, and I can't find any information on this in the service manual. Anyone know what it connects to?
__________________
Bill Shenandoah Valley of Va 1972 GMC 2500 Sierra Grande 402, Custom Camper Package |
![]() |
![]() |
![]() |
#2 |
Senior Member
![]() ![]() Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,815
|
Re: Heater Control Valve
Should be a small vacuum hose coming through the fire wall to a "T" then to the vacuum valve, passenger side cowl and the heater valve.
__________________
other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
![]() |
![]() |
![]() |
#3 |
Registered User
![]() Join Date: Mar 2014
Location: Luray, VA
Posts: 73
|
Re: Heater Control Valve
Thanks for the reply. Unfortunately the previous owner or owners did some fairly sloppy repairs. Lots of wiring and vacuum line errors. In this case, there's no vacuum line in the engine compartment that is unused. The reservoir is connected OK and there's a line to the outside air valve that works. I suspect the heater valve T's into something under the dash, as you say, just need to know what.
__________________
Bill Shenandoah Valley of Va 1972 GMC 2500 Sierra Grande 402, Custom Camper Package |
![]() |
![]() |
![]() |
#4 | |
Senior Member
![]() ![]() Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,815
|
Quote:
|
|
![]() |
![]() |
![]() |
#5 |
Senior Member
![]() ![]() Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,815
|
Re: Heater Control Valve
There should be a tee in that vacuum hose that goes to the air valve. One leg of that T will go to the heater valve.I can't figure out how to send a pic on this phone so I will send you a picture later
Posted via Mobile Device |
![]() |
![]() |
![]() |
#6 |
Senior Member
![]() ![]() Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,815
|
Re: Heater Control Valve
Here's a pic. Also check vacuum. You should have 15+lbs.
__________________
other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
![]() |
![]() |
![]() |
#7 |
Registered User
Join Date: Nov 2007
Location: Los Angeles, CA
Posts: 84
|
Re: Heater Control Valve
This helped me:
![]()
__________________
1970 CST long bed Fleetside |
![]() |
![]() |
![]() |
#8 |
Registered User
![]() Join Date: Mar 2014
Location: Luray, VA
Posts: 73
|
Wow, that's great! Just what I needed to straighten it out. Can I ask where that diagram comes from?
Posted via Mobile Device |
![]() |
![]() |
![]() |
#9 |
Senior Member
![]() ![]() Join Date: Sep 2008
Location: Harrison, Arkansas
Posts: 9,815
|
Re: Heater Control Valve
Note, the vacuum reservoir failed on my truck. I had too little vacuum to close the heater valve.
__________________
other Larry Build thread, Arkansas K10 https://67-72chevytrucks.com/vboard/...=755797&page=5 The ability to speak several languages is an asset, but the ability to keep your mouth shut in any language is priceless. |
![]() |
![]() |
![]() |
Bookmarks |
|
|