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71-74 Javelin Dash Vents |
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CamJam
Moderator Group Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6547 |
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Posted: Oct/22/2019 at 9:15pm |
Just got the a/c working in my '72 Javelin for the first time. The blower fan works fine but the air blows mostly out the defroster vents. The dash vents barely blow any air at all regardless of the setting of the open/closed lever next to the center dash vent.
From the service manual, I see that the open/closed lever apparently controls a vacuum "motor" at the top of the evaporator housing. Since they call it a motor I assume it's electrically operated, but I haven't found it in the wiring diagram. Is this in fact an electric pump that opens/closes a damper by vacuum? TIA.
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'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST '69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD |
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mmaher94087
AMC Addicted Joined: Apr/01/2008 Location: Arizona Status: Offline Points: 1691 |
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I'm not a '71/74 guy but I believe it is a vacuum operated valve like the '70 ram air valve.
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Mike
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CamJam
Moderator Group Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6547 |
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Thanks, Mike. I see from the parts book that the open/closed dash control has two vacuum hoses going to it, so it sounds like you're right. Not sure why they call the part on the evaporator a "motor" in the service manual though. I suppose I need to figure out how the hoses are routed. I doubt I'll be so lucky as to find there's just a vacuum line under the hood that has come loose, but I may as well start with the easy stuff first.
EDIT: Found this post from earlier this year by forum member CHAR, who was working on a'72 Javelin. Gives me some clues as what to look for. "I've yet to get into the vacuum system, but there is a line from a intake manifold fitting, thru the firewall close the the speedo and into the cab to a tree that services the main air flap that lets air up into the upper dash duct work while the A/C is on. It also looks to feed(suck) the heater valve. I want to see about getting it all working again or ditch it and switch it all to manual cables, but aside from parts, it looks simple enough." and yet another from forum member Pit Crew in 2015: "The vacuum supply line runs from the intake manifold to a tee near the "OPEN/CLOSE" switch on the dash board next to the center A/C vent. One side of the tee supplies vacuum to the "OPEN/CLOSE" switch. From the "OPEN/CLOSE switch another vacuum line runs to the actuator on the top of the A/C evaporator box. From the other side of the tee supplies vacuum to the vacuum switch located over on the front of the heater box. From that vacuum switch a line runs back out to the water control valve in the engine bay by the heater core." I think I get the idea now. If I'm not mistaken the vacuum line to the water control valve is '73 and '74 Javelin only.
Edited by CamJam - Oct/22/2019 at 11:16pm |
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'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST '69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD |
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CamJam
Moderator Group Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6547 |
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No sign of a vacuum hose coming through the firewall, so I climbed under the dash to see if I could see any sign of it there. Hey, guess what? I found one! Pulled lightly on it and found it was open on one end. I started the engine up, turned the a/c on, sucked on that hose like I was drinking a Wendy's milkshake through it, and immediately the dash vents started to blow cold air! |
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'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST '69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD |
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pit crew
Supporter of TheAMCForum Joined: Jul/08/2007 Location: delete Status: Offline Points: 5341 |
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73 Hornet - 401EFI - THM400 - Twin Grip 20 |
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