1963 AC Hot Water Shutoff Valve PN 1479664

[Harry S.]

A quick question.

Does anyone know the minimum vacuum required to activate the AC Hot Water Shutoff valve?

Thanks

[Larry M.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

A quick question.

Does anyone know the minimum vacuum required to activate the AC Hot Water Shutoff valve?

Thanks

Harry:

It is not very much, since I can suck on the small diameter hose to the hot water valve on my car and check its open/close operation. My guess is probably around 8-10 in HG vacuum.

Larry

[Harry S.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

Harry:

It is not very much, since I can suck on the small diameter hose to the hot water valve on my car and check its open/close operation. My guess is probably around 8-10 in HG vacuum.

Larry

I think I'm getting about 6. I have 18 from the carb. to the vacuum switch and it looks like 6 from the switch to the valve. Think I'll get a new vacuum gauge.

I already know the valve is bad, it never closes. Just trying to avoid replacing a good vacuum switch.

Thanks

[Claus S.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

So the vacum on the AC Hot Water Shutoff valve goes to the carburator?

[Harry S.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

So the vacum on the AC Hot Water Shutoff valve goes to the carburator?

No, on a 63 it goes from the carb. to a brass vacuum switch that is on top of the heater box behind the glove box. When you pull the heat lever on the dash the plunger on the vacuum switch is released and allows vacuum to to hot water shutoff valve. The vacuum to the valve opens the valve and allows water into the heater core.

I'm trying to determine if my vacuum switch is bad. I already know my hot water shutoff is bad.

[Claus S.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

I see. Thanks Harry

[Larry M.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

Harry:

As I stated before, these vacuum switches will go bad over time. The internal rubber o-ring (or rubber cylinderical ring seal) will deteriorate. I believe that the switch also has a small air bleed built into it. So your low vacuum out of the switch may be a switch that is pulling in some air and also restricting the full vacuum source. As I mentioned before, they can be rebuilt. The switch on my own car sticks frequently and takes a long time to change HEAT and COOL positions....but I just live with it at the present time.

I have HEARD (read a few articles) that the new ones had some manufacturing issues and didn't always work as intended. Perhaps this was just the very early ones when they first came on the market. Maybe others will know more about this. If you do buy new, check it out very thoroughly BEFORE installing on your car. If I remember correctly, the folks that did have problems were able to do something to make the switch work better....but I don't know what they did. I may be able to find out by doing a search at the "other forum".

Larry

EDIT: Here is a link to this repair thread. http://forums.corvetteforum.com/c1-a...uum-valve.html

[Harry S.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

Larry, I agree with you.

It's hard to tell if the switch is good or bad. If I knew the what vacuum was required by the hot water shutoff it would make the decision more binary.

Thank You

[Larry M.]

Re: 1963 AC Hot Water Shutoff Valve PN 1479664

Harry:

See the new link I just included on my last post.

I do not think that 6 inches HG vacuum is good enough to ALWAYS and RELIABLY work the hot water valve. I think you will need more vacuum than this. You can buy a new reproduction hot water valve and then test it so that we all will know.

Larry