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I have two electrical issues with my 71 Corvette coupe. First, the windshield wipers do not work. The door opens when I use the override control, but the wipers do not run. I checked the switch and it is good. Fuse is okay. I used a tester and I have juice at the switch but I get none at motor where the hot lead goes in, and there is none at the switch/button that is depressed when the door opens. I'm not sure how to check the relay(s). It seems there is alot that has to happen for the wipers to work. I guess the first thing is...the door does not open when I turn on the inside switch/control. Is this a vacuum issue? What tells the door to open? Why does it work manually? Maybe someone can explain the process to me or direct me to a source of information....Second. I get no juice at the a/c compressor when I turn the a/c control to airconditioning. Again, the fuse is good. The blower works fine. I'm sure there are relay(s) somewhere for the a/c too....I'm at a loss. I talked to an auto electric shop here in town and the guy wasn't optimistic or thrilled about working on it when I told him it was a Vette, mainly because of the vacuum operated wiper door. HELP!
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May the Good Lord Help You
If you are using the 1971 AIM, Workshop Manual or the CIA schematic.
Geoffrey Coenen
PS: CIA = Colored In AIM -
Re: May the Good Lord Help You
I have an Assembly manual. 71 service manual. and a color wiring schematic... Are those what you are talking about? Are you trying to say there is no one that can help?Comment
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Re: May the Good Lord Help You
There are several on this board that will post shortly. Your's is not a unique problem, it goes with the territory of '68-'72Dick WhittingtonComment
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Re: 71 windshield wipers and a/c
Mark
If you can override your door with the manual override under the steering wheel / dash area, then your vacume system is working.
you said that you have power out of cockpit switch to your door open switch, but no power to your wiper motor, the little switch thats on the firewall that gets depressed when the door is open ( yours might be on the wipers itsself 68 is on the firewall) is a safe switch in case of vacume not working to keep the wipers from slaming up thru a closed door.
I would start at this point and check this switch and wiring to motor,
as for your A/C my 68 has none and I know that system has a bunch of relays but have not work on that system,
good luck
MichaelComment
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Your copy of the '71 Chassis Service Manual
gives a nice discussion of the wiper door system. It describes both the vacuum and electrical aspects of it and shows who does what/when in the process of the door opening, the wiper motor turning ON, the wiper motor turning OFF and the wiper door closing. In short it's an electro-mechanical system and all the component parts have to operate properly for the system to work.
When you flip the wiper switch on the center console, you send electrical instructions to the vacuum relay (mounted on the rear of the tach) to open, vent vac, and cause the wiper door to open. The over-ride switch beneath the steering column is in series with this vac path. If either or both valves vent vac, the wiper door should open....
Common causes for the wiper switch failing to actuate the wiper door are:
(1) Your center cluster bezel is cracked and you have no ground reference for the wiper switch to the tach mounted vac relay.
(2) The tach mounted vac relay is defective or mounted improperly (no valid ground reference).
(3) Bubba has been under the dash and has the control side vac lines mis-routed. The sequence is from the engine compartment to/through the tach mounted wiper door relay, on to/through the over-ride switch, and back out through the firewall to the wiper door actuator.
Once the wiper door opens via vac actuation, it contacts a micro switch mounted on the firewall causing it to 'make' (the door is open and it's now 'safe' to turn the wiper motor on). That allows power to flow to the wiper motor IF the over-ride switch beneath the steering column is properly connected and set to the ON/RUN mode. The microswitch position is physically adjustable and determines how soon (if ever) the wiper motor starts upon wiper door opening.
The electrical over-ride switch beneath the steering column is there to allow you to HALT the sweep of the wipers in order to perform maintenance...change wiper blades. MANY times novice owners find their wiper motor doesn't work because the electrical over-ride switch was inadvertantly left in the OFF or SERVICE mode denying the wiper motor power. This is a 'cockpit' error resulting from failure to read the owner's manual and/or the chassis service manual to understand the basic system....Comment
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