'81 heater vacuum control valve need help!
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 28
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'81 heater vacuum control valve need help!
Ok guys, need help again! I'm trying to track down a leak on my heat/ac system. I pulled out the control valve to test it and this is what I have. By the way testing it with a mighty vac connected to the source port and have all the other ports blocked. With the control valve "OFF" it holds vacuum fine. Move the valve to any other position and it loses vacuum. Setting the valve to any position other than "OFF" and trying to pump it up it will not hold vacuum. Bad valve?
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Which value are you asking about, the one on top of the heater core cover or the one that is inline with the heater hose?
If memory serves me correctly, the one on top of the heater core cover controls the inline valve....but it has been awhile since I had this area apart.
If memory serves me correctly, the one on top of the heater core cover controls the inline valve....but it has been awhile since I had this area apart.
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 28
Likes: 0
Which value are you asking about, the one on top of the heater core cover or the one that is inline with the heater hose?
If memory serves me correctly, the one on top of the heater core cover controls the inline valve....but it has been awhile since I had this area apart.
If memory serves me correctly, the one on top of the heater core cover controls the inline valve....but it has been awhile since I had this area apart.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Lanny, I'm talking about the one on the control head. The one you select a/c, vent, defrost, and heat with. I've checked the one on top of the heater core cover and it is good. The hot water control valve that is in line with the heater hoses is bad. All of my vent actuators are good. The only part in question is the control valve in the a/c, vent, etc. selector. My original part was bad as it would not hold vacuum in any position. The new one will hold in the "OFF" position but no other. I am blocking off the ports that go to the actuators while testing this new part. I assume it should hold vacuum but it does not.
I had the exact same problem several years ago. After about 30 years the 7-hose (?) rubber plug with the 7 hoses gets worn real sloppy and fails to hold vacuum. I resorted to cutting my hoses off one-by-one and plugging them directly onto the zinc vacuum switch (I did paint each hose and nipple a different color and also drew a diagram showing which hose goes to which nipple). Once I plugged the hoses directly onto the nipples I had no more vacuum leaks.
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 28
Likes: 0
I had the exact same problem several years ago. After about 30 years the 7-hose (?) rubber plug with the 7 hoses gets worn real sloppy and fails to hold vacuum. I resorted to cutting my hoses off one-by-one and plugging them directly onto the zinc vacuum switch (I did paint each hose and nipple a different color and also drew a diagram showing which hose goes to which nipple). Once I plugged the hoses directly onto the nipples I had no more vacuum leaks.
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Surgar Bear: okay got it. I would think that it should hold vacuum like you are thinking and testing. If I remember correctly the control is only held together with a clip. Try putting some silicon spray on the rubber seal; might help, might not.
I should get my old one out and see what it does...except I just remembered my hand vacuum pump broke last time I used it.
Off to Harbor Freight I go.....I knew I needed something from there.....
I should get my old one out and see what it does...except I just remembered my hand vacuum pump broke last time I used it.
Off to Harbor Freight I go.....I knew I needed something from there.....
Thread Starter
Intermediate
Joined: Mar 2014
Posts: 28
Likes: 0
Surgar Bear: okay got it. I would think that it should hold vacuum like you are thinking and testing. If I remember correctly the control is only held together with a clip. Try putting some silicon spray on the rubber seal; might help, might not.
I should get my old one out and see what it does...except I just remembered my hand vacuum pump broke last time I used it.
Off to Harbor Freight I go.....I knew I needed something from there.....
I should get my old one out and see what it does...except I just remembered my hand vacuum pump broke last time I used it.
Off to Harbor Freight I go.....I knew I needed something from there.....
Navigator
Joined: Sep 2013
Posts: 9
Likes: 0
From: Merced CA
Vacuum diagram
I had the exact same problem several years ago. After about 30 years the 7-hose (?) rubber plug with the 7 hoses gets worn real sloppy and fails to hold vacuum. I resorted to cutting my hoses off one-by-one and plugging them directly onto the zinc vacuum switch (I did paint each hose and nipple a different color and also drew a diagram showing which hose goes to which nipple). Once I plugged the hoses directly onto the nipples I had no more vacuum leaks.
Mark
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Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Oh no, I have the diagram tucked away under my console so the only way I can retrieve it is to tear my console apart. The sad part is I had my console ripped apart for a whole month while I was waiting for my new radio to arrive and I just installed it 3 days ago.
Navigator
Joined: Sep 2013
Posts: 9
Likes: 0
From: Merced CA
Oh no, I have the diagram tucked away under my console so the only way I can retrieve it is to tear my console apart. The sad part is I had my console ripped apart for a whole month while I was waiting for my new radio to arrive and I just installed it 3 days ago.
Mark
Navigator
Joined: Sep 2013
Posts: 9
Likes: 0
From: Merced CA
Mark
Navigator
Joined: Sep 2013
Posts: 9
Likes: 0
From: Merced CA
Discovery
So I looked at this picure (http://shop.docrebuild.com/1977-1982...M14009285.aspx) figure 1 and am still lost (old age i guess). How do these valves control the dash vents? Which one is the culprit..? Thanks..
Mark
Mark
Mark