AC heater control panel vacuum switch rebuild

[JayEstes 172]

Have any of you successfully refurbed the vacuum switch in your heater control panel?  Seems like a very hard part to find.  Looks like this one:

http://www.ebay.com/itm/NOS-1969-1970-FORD-MUSTANG-SHELBY-AIR-CONDITIONING-DAMPER-DOOR-SWITCH-/161380694557?pt=Vintage_Car_Truck_Parts_Accessories&hash=item259309fa1d&vxp=mtr

(But I'd rather not get robbed like that)

 

Mine seems to be in good shape, but I believe the internal parts of the switch are leaking, and I can't get the vacuum motor that switches from defrost to floor to respond (the motor that has a port on the end and the side).  When I check that motor outside the car - works, and holds vacuum, seems the switch is leaking and not providing sufficient vacuum to this motor.  Other functions seem to work fine in my car.

 

Any help? I couldn't find much in searching the forums.

 

Thanks in advance.

[Wycked69 20]

Good question, Looking at how the two halves are assembled It appears the center shaft is "swagged" on the bottom side to hold the two sections together. Therefore, having to use a countersink bit of some type to remove the swagged portion would not leave you with the ability to retain the use of the center section when reassembling and would require a new center section to be machined. 

 

If you take it apart, please post photo's as it makes me curious if it has rubber O-rings or rubber wipers to create a seal in order to maintain vacuum.

 

"Inquiring minds want to know"

[JayEstes 172]

I will keep everyone posted.  You are correct that the center point for this item is "swaged", or pressed, as a permanent fixturing.  You can "unwind" the spring on the top side which allows you to seperate the parts about 1/4in.  I have tried taking that off, cleaning and re-installing the spring, but no joy.  I don't believe there are o-rings, it seems to me that the rubber has been formed onto metal, and there must have been formed grooves which allow proper connectivilty between channels depending on lever position. 

 

I may wind up buying a replacement part and experimenting on that first - I'd hate to ruin my original part.  Interesting that I can find very little info about this part on the web.  They aren't sold much - what is out there is crazy expensive (and possibly just old or used and could have the same probs), and I can't find ANYTHING about rebuilding them. 

 

If anyone else has thoughts, please chime in.

[JayEstes 172]

I almost forgot, but wanted to let everyone know that I was able to "repair" my switch.  And it wasn't too bad to do.  I also developed a way to test it, which I will talk about.

 

If you look at the switch, on the top side, there is a conical spring that is used to keep the rotating part of the switch in pressure contact with the non-rotating part.  I removed this spring by using a small flat head screwdriver under the lip of the central hub.  Rotate the screwdriver around to release the spring little by little.  Once released, the joint under pressure now has about 1/8th to 3/16th inch it can open.  I did my best using soft materials to clean the two surfaces, and then I decided I need a new spring, cause the one I removed seemed like it had very little spring force to hold everything together.

 

Went to a favorite fastener website www.mcmaster.com and ordered 3 conical springs:

 

 

I wound up using the shortest one (still longer than the original spring but that was as close as they had in stock.  I was able to work this entire spring into the mechanism with a small amount of effort.  Once in, this joint seemed nice and tight, a slight rotational friction resistance against the selector switch, but much better than before.

 

I also devised a way to bench-check the vac switch.  I put short tubes on all of the ports, and plugged them all.  Then, in the black port (generally found to be the "source" vacuum, I put my brake bleeder and pumped up the system.  I found it held vac really well now, and it would leak "just a little" vacuum as I switched from selection to selection.  I took some videos of the switch in checkout which I have posted to vimeo.  You can see them here:

 

 

 

After this refurb work, my switch seems to be working great.  I can run the car for awhile, with the switches set in a certain position, and even days later, I can move the switch, and the system is still holding enough vacuum to move the vac motors to move flaps.  usually only once or maybe twice as some vac is lost with every switch throw.

 

Anyway - I was able to work thru this problem and I didn't have to buy new parts (which are next to impossible to find) and I didn't have to "unswage" the original part.  if you have problems with the vac performance of this part, give this fix a try.  

 

it worked for me.

 

Jay

[SA69mach 39]

Nice job. Thanks for the post and the videos.

[1969_Mach1 333]

I have luck separating parts held together by swaged or flared pins/rivots by drilling off the flared portion like Wycked69 mentioned.  Then to reassemble, drill and tap a hole in the center of the pin for a suitable sized screw.  Use a button head or other style of your choice to reassemble the parts.

 

JayEstes, McMaster Car is also my first source for odd or speciality fasteners and hardware.  You can't find a better assortment at one place.

[JayEstes 172]

Thx guys.  I was thinking of drilling out the swage and figuring out how to refit, but several difficulties do that:

 

1) the diameter of the hole required in this switch is something like an inch - thats big for a metal cutting bit, and while I have a drill press, proper centering and holding are a concern.

2) This is a unique part, and the underside of this swaged on piece had something like a rubber with very specific set of channels formed into it when it was formed to the metal in question.  Trying to get a pin bolted to it etc afterwards looked tricky and I basically had to tear it apart to begin to understand how to fix it.  Seemed high risk to me.

3) replacement parts are hard to find - period.  Made me nervous I would dork it up and then spend more weeks with the dash blown apart trying to find a new part.

 

Anyway - if I had had no luck with a new spring- I was probably headed that way - I wasn't gonna put the dash back together without the AC vent system working right.

 

So I got kinda lucky.  I think replacing the spring might be a good option for other folks - doesn't take long or cost much.  Also, I came up with a way to check it out on the bench that gave me plenty of confidence.  I was happy with the way it turned out.

 

Thanks for the feedback guys - hope this solves someone else's similar issue down the road.

[MikeStang 247]

How about I just sale ya My complete entire WORKING control head for about 75 bucks plus shipping?

[JayEstes 172]

If you go price all those pieces in there you might find that it's worth significantly more than that.  Some of the little switches are 20-4- bucks.  If I needed one, I might just take ya up on it!  I got plenty of things to spend the cash on right now.