AC mode switch / vacuum troubleshooting

[Ron]

Half say use vaseline, half say don't....I'm going to use Vaseline on one half of it, silicone on the other half.

LOL
It all depends on the rubber (natural, synthetic, etc). If its viton like the PPR o-ring, no problem even with gasoline.
Play it safe and use the silicone grease.

[Rich_NYS]

~snip~

I polished the metal part to a shiny surface and coated the rubber part with 'baby powder', still working fine for over 25 years!

I'm going to try this...thanks for the tip!


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[Rich_NYS]

So far nothing stops the hiss. New diaphragm hisses & whistles, cleaning & polishing seemed to help a little.

FWIW, I don't think the new diaphragm is a proper fit. The old one had raised "keys" the same size & shape as the switch....the new one has "keys," but three are not the same size & shape.

I tested with smoke and can see it getting sucked into the edge of the diaphragm.

I put everything back together....aggravation for a different day.

Probably sell the new diaphragm.

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[Ron]

Maybe try putting a very thin washer under the two plastic prongs to shim it tighter. You can notch the hole to shape with a square/box file.
If you're lucky, you can locate a horseshoe clip to fit. (It's brittle -- I'd try aligning it all up and press the plastic through all at once, instead of slipping it under the plastic prongs. Wash the back side of the diaphragm (for grip) and lots of silicone on the maze.)

[David T]

You should not be having so much trouble with this. Maybe somehow you don't have the right switch or someone messed up the parts. One thing you could do is send the switch out to a Delorean vendor and ask them to assemble it for you. They would immediately see if something is not right knowing exactly what it should look like.

[Rich_NYS]

Maybe try putting a very thin washer under the two plastic prongs to shim it tighter. You can notch the hole to shape with a square/box file.
If you're lucky, you can locate a horseshoe clip to fit. (It's brittle -- I'd try aligning it all up and press the plastic through all at once, instead of slipping it under the plastic prongs. Wash the back side of the diaphragm (for grip) and lots of silicone on the maze.)

I was thinking I needed it tighter, and tried "elongating" the spring early on. I'll try the washer idea on the next go-around.

You should not be having so much trouble with this. Maybe somehow you don't have the right switch or someone messed up the parts. One thing you could do is send the switch out to a Delorean vendor and ask them to assemble it for you. They would immediately see if something is not right knowing exactly what it should look like.

I agree, it's a pretty simple task and I shouldn't be having such a hassle. I like the idea of sending it to a vendor for a more experienced set of eyes (and better part-swapping resources.) I don't need help assembling it, though....every part of it is keyed, it seems pretty foolproof to reassemble.

I have an odd thought/silly question: is it possible that too much vacuum could be causing the issue? I put a gauge on my manifold, it's at the high end of the scale/

[David T]

The motor can't produce "too much vacuum". Maybe take a ride to PJ Grady with it.

[Rich_NYS]

The motor can't produce "too much vacuum". Maybe take a ride to PJ Grady with it.

Lol....not going to drive 200 miles for a HVAC switch. Ain't nobody got time for that!

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[David T]

Then either have him do other stuff too or just mail him the switch. I would call first.Or wait till you have other business in the area nearby.

[Rich_NYS]

Today I picked up my latest DeLorean purchase. The owner had a small parts stash, and coincidentally it contained one of these: