CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Windshield wipers

I just heard a discussion about stopping the wipers in any spot on the windshield to allow the driver to reach out the window to shake off the snow. I live in snow country also, and certainly know what they were talking about. They have front and rear windshield defrosters, butt warmers in the seats, why don’t they have defrosters built into the wiper frame to keep snow from sticking to them ? ? ? ? That always seemed to me such a simple and SAFE answer to this problem.

This is the second time you have said a capacitor returns the wiper to the stop position. How would a capacitor know how far to move the wiper? There is a switch inside the wiper motor that is connected to power not effected by the dash switch. This switch is closed when the wiper is not in the rest position, and open when the wiper is in the rest position. When the dash switch is shut off the internal switch powers the motor until the wiper gets to the rest position, and then opens up and the wiper stops. If this switch breaks the wiper will not return to the stop position, but the wiper will simply stop when the dash switch is shut off.

“The car is shaky,” said the caller with the wiper problem. “Well, it’s a Subaru,” he added. To which Tom or Ray quickly threw in, “I like Subaru.” Fair enough, but Car Talk also runs a “supported-by-Subaru” ad. I’m a satisfied Subaru owner, but I don’t think that Car Talk should run ads from car makers whose products are likely to come up in the discussions, and this exchange was a case in point. It’s fine to express your opinion on a car, Bob & Ray, but you create a credibility gap when the manufacturer supports the broadcast.—Drifter

What about winter wiper blades and use eng hot coolant to warm the windshield washer fluid

I agree with TR6. The capacitor idea makes no sense since a capacitor would only keep the wipers running for a fixed time after the wiper switch is turned off. So what if you shut the wipers off just before they reached the park position? They’d overshoot.

The limit switch method is obvious and simple, and routine in situations like this. Even the caller figured that’s how it’s done.

I laughed as I was listening to this. Years ago, my husband & I were heading over a pass in NE Oregon, it was snowing heavy wet flakes that were sticking on the wipers. My husband kept reaching out the driver side window and smacking the wiper…kind of a quick lift & drop motion. I think I tried on my side but wasn’t as good at it as he was. It’s been a few years so I don’t remember all the details but somehow, he lost his wiper. We stopped, he got out frustrated and mumbling, the snow coming down heavier now and tried to get the passenger side cleaned off. Frustration took over and before I knew it, the passenger side wiper was flying through the air and he was now shouting. What to do…heavy snow, no wipers, baby in the back seat, all in the middle of nowhere but luckily very little traffic. We rolled down both windows, attached a pair of his yellow work gloves to the wiper arms, stuck our heads out the windows in attempt to see better and headed down the hill. I’ll never forget how hillarious it was to see two hands waving at us all the way down the hill & how the snow flew into our eyes making it almost impossible to see. What topped it all off was the looks on peoples faces as we drove into the closest auto parts store to get a set of wipers with two gloves waving at them.

I guess I was lucky when I was a ski bum. Or had exceptionally sturdy windshield wipers. I lived near a ski resort in Colorado. I had a 62 Ford Galaxy. Steel studded snow tires. I must have drove back and forth to that resort 500 times or more, sometimes in severe winter blizzards where it was snowing a foot every hour or more, and never once did I have a problem with the windshied wipers being able to remove the snow from the windshield. I just brushed off whatever snow had accumulated while parking before I started is all. The windshield wipers did the rest.

Yeah. A capacitor is about as booooogus an answer as you can get. How could a capacitor have any effect on where wipers stop? Plus they would continue to run after you turned the ignition off due to the stored energy, which they don’t, hence no capacitor.

The reality is that there are two circuits built into the motor. One circuit runs whenever the wipers are in any position other than park. The other circuit also runs when the wipers are in park and the wiper switch is on. It’s not rocket science. Switching off the wipers leaves the park only circuit active, such that the wipers will return to park and the circuit becomes inactive,

Maybe the capacitor reference was for the WW intermittent mode? You know, where they operate every 3 -10 seconds depending on how the driver adjusts them? A capacitor (in conjunction with a variable resistor) is probably used for the delay timing.

A thermal relay is the best device for the intermittant mode. It heats & closes, tripping the circuit for one cycle, to be tripped again wneh it again heats up. Speed control is easy via the use of a stepped resistor.