baxsom

I havent really dug too deep into the headlight/wiper door function on my 72. The headlights come up and the wiper door comes up IF I pull the over ride. the actual wiper switch doesnt operate the door. It does turn on the actual wipers though. I figured it was just some quirk and not to mess with it in case i made it worse. I then read about a solenoid under the dash that is supposed to work the wiper door when the switch is turned on. I also read about a switch near the radio. Which one does what? Does the solenoid behind the tach work the wiper door or one near the radio? I am thinking of replacing every hose, actuator and relay. I found the wiper door solenoid that goes behind the tach for sale. what is the component that sits near the radio called so i know what to look up for a replacement part. I read one thread where they called it the relay but looking up relay only gets me actuator relays and the one for the wiper door is behind the fender.
Any advice, hints, help etc. Ps when I crank the car the wiper door goes up and then back down.

7T1vette

Each of the devices in the headlight and wiper door system are very simple on their own...and are easily checked out for function, once you know how they are supposed to work. For example, the solenoid/switch you mentioned (attached to the back of the tachometer housing) is activated by 12 vdc and allows vacuum to flow from one passage to another. {Note: the third 'connection' at the end of the unit is a vent and does not have anything connected to it...but there is a 1/2" cube of open-cell foam pushed over it to act as a filter.}

If you remove this device, you can hook a couple of slave hoses to the vacuum line connections, then apply [and dis-apply] 12 vdc to the solenoid and check for clear flow of vacuum (or low pressure) in one mode and complete blockage in the alternate mode. If the device does not work as intended, but the solenoid functions properly, you can likely fix the unit by flushing it out with a little soapy water, then letting it dry thoroughly before applying voltage to it.

The other devices in these vacuum systems are just about as simple and are easy to check out once they are removed from the system. Trying to trouble-shoot these vacuum systems with everything connected can be done, but you need to be very knowledgeable about the system and how to trouble-shoot it correctly. Hoses usually are not a problem, except if they are exposed to direct sunlight (wiper cowl area) or near high heat; then they can degrade and be a source of leakage. Replacing all devices can be expensive...not to mention that the quality of the 'new' [aftermarket] units is not nearly as good as the original units were if they are still functional. Advice: first check all hoses and components individually; then replace only what you must; then do a check-out of the new device to make certain it isn't junk!

baxsom

Thanks, I will work on testing this stuff out first. I am hoping that the solenoid is clogged or unhooked or something. I havent got under the dash yet to look. The wiper switch turns on the wipers so its working at least. Something in the normal circuit is not telling the door to open. What part is it that I keep reading is by the radio then? I had to put a new cone shaped rubber seal in the wiper actuator so far. I am definitely going to replace all of the hoses. They are brittle looks like some cracking. Cheap enough and seems easy enough to replace to justify going ahead and doing it.