I drove the Corvette to work all week again this week while I had the Malibu down getting a wheel repaired and two new tires. It rained like a son of gun this week and it did pretty good. However a few weird things happened.

My windshield wipers would intermittently get stuck in the on position. No matter how I messed with the switch on the stalk they would not change speed or stop... until I did one of two things. 1) turn the automatic temperature control unit on and then off, or 2) turn the car off and then back on to reset the wipers.

I also have noticed a weird vibration in the drive train of all things and I can reproduce the vibration by turning the automatic temperature control unit on or off. AC ON feel the vibration in the drive train immediately, AC off it goes away. I can't see or notice any vibrations from the compressor or AC components when I observe it when idling and turn the ac on or off.

I'm scratching my head on this one.

Make sure tha AC brackets are tight. That compressor may truly be bad. I would only get that vibration at 2k with it. When I switched it out the new one did the same. Then we figured out a bracket was missing on my car, and that was causing the vibration.

Turn the AC on and slowly rev up the engine by hand to see if the compressor starts to shake.

The wipers sounds funky, for sure... but think this way... power loading.

Let's say there is something amiss inside the motor assembly, or even the switch. Turning on the AC on my car causes a rather dramatic current/voltage drop to occur. I am wondering if the same drop doesn't wake up the wiper motor?

As for the vibration, there should be three braces that hold the AC and alternator to the bracket.

1. the rear brace.. This bolts from the intake to the alternator to the AC part of the bracket, next to the alternator.

2. Brace from behind the alternator to the #2 exhaust manifold bolt.

3. From behind the compressor to the #3 exhaust manifold bolt.

Braces 2 and 3 become tricky when headers are added.

I updated the image below from the Helm Manual to fit my text above. It's from 1992, but all LT1s are the same.

Attach file:

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  LT1AlternatorACBracketAssembly.jpg (84.01 KB)

My 92 because of the headers and valve covers is missing brace 1 and brace 2 - so it has a funny virbation at WOT or near WOT when the AC compressor is running. I did build a spacer so I could have brace 3 on it to keep it from breaking the alum bracket.

The wipers do a similar thing in my 92 - If they are wide open they won't slow down if you click the switch back one at a time - but I can get them to act right by turning the speed (from wide open) all the way down (or off) then going to the speed I want. It's done this since I bought it in 2005 (car had less than 40K miles on it) and I just assumed it was normal GM quality.
Will

Will - I don't even know where to start fixing that one. It could be the switch, it could be the motor... it's really hard to say.

My wipers work as expected. Odd, the day I test drove the car, the wipers didn't work at all. The owner, Joe, was shocked. He had just used them a few days ago. He checks the fuse, all is well, puts it back in, and they work.

So... I wonder if killing all power to the circuit - ie, pulling the fuse - won't help reset something internal.

Quote:

I'm putting my car back together so I wanted to check this thread for the bracket placement. There is one missing from the diagram. It connects to the same bolt as #3 on the manifold then to the outside of the compressor on the bottom right.

http://www.corvette-guru.com/modules/ ... id=132878#forumpost132878