wiper arm switch
Good evening. I have a simple question dealing with the 1972 wiper system. On start of the engine the wiper door opens and stays open till I shut the car off. See several tests with the windshield wiper arm vacuum control switch. Some say vacuum pull the with white tube, other say vacuum the red. Which one and where to buy a GOOD one? Thankyou
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Re: wiper arm switch
I can't see the switch test here in the hotel on the road to the Convention, but my guess is you have a leak in the vacuum control system. The vacuum system consists of two systems. The system with the larger volume is the operating portion of the two systems. The control part of the systems has the lesser volume. The control portion consists of the smaller diameter hoses and the control diaphragms. When the engine is started and vacuum comes up, the control portion of the system should receive vacuum first. With no vacuum leak vacuum enters the control part first which should keep all the vacuum operated parts in the position they were when the engine was shut off. If there is a vacuum leak in the control system the vacuum may enter the operating system first and leave the control portion to lag behind the operating system. There are springs in the vacuum relays that set those valves to operate the doors to open for safety reasons (headlamps up and wiper door open). Thus, with a leak the headlamps will blink or wiper door open. There is more volume in the highlight circuit (two large actuators and larger and longer hoses)) than in the wiper door. Thus, the wiper door operates first.
Cliff notes: you likely have a leak somewhere in the system but then you knew that. My message is that it may be anywhere in the entire system. Be Shure to test the other portions of the entire system before you begin replacing parts. You may have done that, but I can't tell that from your original post.
Sorry this is so long. I hope it makes sense.Terry
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