Headlight vacuum relay question.
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Joined: Jul 2003
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From: Smithton il
Headlight vacuum relay question.
I am troubleshooting the headlights on my 80. I found one of the actuater shaft seals is bad, but my question is related to the two vacuum relays. Are they supposed to hold vacuum? I tested the vacuum canister and it holds vacuum up to the yellow vacuum lines running to the relays, but the relays do not hold vacuum when the yellow line is plugged into them no matter what position the lights are in. I would think that they should hold vacuum, but want to make sure before spending the money.
Also, the vacuum feed for the lights also feeds the vacuum for the climate control. I am having problems with these contols as the air only blows down by my feet. I am thinking that if the vacuum pressure is leaking through the relays this might cause the climate control to be starved for vacuum and the plenuem not to open and allow air to flow through the vent. What do you think?
Thanks
John
Also, the vacuum feed for the lights also feeds the vacuum for the climate control. I am having problems with these contols as the air only blows down by my feet. I am thinking that if the vacuum pressure is leaking through the relays this might cause the climate control to be starved for vacuum and the plenuem not to open and allow air to flow through the vent. What do you think?
Thanks
John
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Joined: Aug 2001
Posts: 667
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From: College Station TX
Re: Headlight vacuum relay question. (Jmccreary)
Yes and No. I'm pretty sure your talking about the vacumn control valves ... so YES, the diaphram inside should hold vacumn ... to the one side which is "under control". This valve opens and closes by the signal line ( on top ). If it is getting a "closed" signal, then the closed side should hold a vacumn ( and the Open side would not ... and visa-versa.
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Joined: Jan 2001
Posts: 4,660
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From: South Central Louisiana
St. Jude Contributor
Re: Headlight vacuum relay question. (Jmccreary)
These relays are very common for leaking vacuum. I have never seen one not leak, but then again I have never seen a new one in action.
Try bypassing your relays to see if you can get your HVAC system to work properly.
Try bypassing your relays to see if you can get your HVAC system to work properly.
