Welcome all 928 forum refugees!
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By Shifted
Given that the HVAC Vacuum Solenoid Valves are no longer available, I took a look at alternatives. The wiring and plumbing of any of the generic valves is easy, but getting them to fit in the same general location as the originals would be challenging. Not impossible, but more work and clutter in the center console than I would consider ideal.

I came across these:

Similar dimensions as the OEM valve, although I haven't actually measured the OEM valves yet. They are designed for water and air, despite the "water" labeling. The way valves work for vacuum, you would connect the "source" (engine side) to the "out" and the HVAC diaphragms to the "in". Which means that they would be plumbed exactly the same as the OEM valves with the "manifold" attached to the "out" on these replacement solenoids. They look remarkably similar to the OEM valves.

The one big question about their design is whether or not they are direct acting valves. If so, then they should work fine. If not, then they might work or might not. Of course, how long they would last is also another unknown, among several.

At these prices, I think that it's worth taking a flier on them and ordering five to see if they could be made to work.

https://www.ebay.com/itm/DC-12V-Micro-E ... 3514058760

I'm not a big fan of spending money on Chinese products when there are alternatives, but there really aren't any alternatives in this size and configuration.

Unless someone has a better alternative besides used valves, or has experience with these valves in particular? I don't mind paying good money for brand new valves, but I'm hesitant to buy used valves, or even new-old-stock, that already have their failure clock ticking.
User avatar
By SeanR
Very nice find. I've been buying all the old ones I come across so I've got a decent stock of them, but having a new valve would be fantastic. If you try it out, please keep us updated.
User avatar
By Shifted
I also found this:
So, I've ordered two samples of the 5 way valve from the factory. A slight premium for just ordering samples, but about $45 all in for two of them with shipping. ETA is in about a month. For a regular order, the minimum quantity is 100, which may be worth it for a vendor, but not for a test. If that assembly works out, it would be a drop in replacement for the entire set of solenoids including the manifold. The only thing to sort out would be the wiring and mounting.

I've also ordered five of the individual valves.

When they arrive, I'll mock them up and see how they hold up to the normal vacuum levels in the 928 both closed and open.

Interestingly, it turns out that the individual ones are designed for breast pumps. Which operate on vacuum, so these valves should be ok. I guess we'll see!
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User avatar
By worf
User avatar
By Shifted
Good news and bad news. The individual valves arrived. They are of a comparable size, hold vacuum well and work well with 13.8v.

The bad news is that they do not exhaust when power is removed. The result is that you can open it and apply vacuum to the target device (HVAC diaphragm), but when the valve is close, it leaves the vacuum applied to the target device. The factory valves, on the other hand, exhaust the outlet to atmosphere.

This could be overcome with a second set of valves that are normally open, but I think that I can find valves that either have a built in exhaust function, or are two way valves. I'll do some more looking.

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User avatar
By Shifted
The latest valves work great. They exhaust properly and hold vacuum. However, I don't like how the port is oriented vis-a-vis the mounting holes. They are functional, but not as clean of an install as I want. They are plan B.

I received a set of five connected valves, all mounted on a nice rail, ports oriented properly, perfect size, etc. However, they were configured for 24v, not 12v. They do work well, but we don't have 24v in the car. I've asked the manufacturer to send me samples in a 12v configuration. I've also ordered a couple of other alternatives that could/should work.

Eventually, I'll get a nice drop in replacement sorted out.
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User avatar
By Shifted
I now have two versions on the way. One is a set of five valves with a common input connecting all of the valves, with the valves mounted on a common rail. I am most hopeful about this one. It should be almost a direct drop in replacement for the entire rail and set of oem valves.

The other valves that I have coming are individual, but designed to be connected together in series. These will require more work to mount, but may provide a good alternative if the other version doesn't work.
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User avatar
By Shifted
The latest round of valves arrived. This is where things are at:

1) I have individual valves that can be used to directly replace the factory valves one at a time. So, you can just replace the one valve that's bad. It will slip into the existing rubber exhaust manifold. However, due to how the outlet on the valve faces, you can't screw the body to the mounting rail. An "L" bracket is possible. I don't have a lot of interest in taking this particular version any further. But, I have a bunch of them, so if someone wants one, let me know. I may revisit this and make up some "L" brackets, or maybe not.

2) I have an assembly that has the valves all in a row mounted to a ridge plastic manifold. It looks really promising except...it only has four valves. Either me or the manufacturer messed up the order. I'm not sure that it's worth getting a 5 valve version of this because mounting this to a rail will require very specific length machine screws. Definitely doable, but it seems like it will be harder to get that sorted out than the next option...

3) I have individual valves that plug together in series to create a single unit. They create their own manifold and the inlet is on the correct end, so you can use a rubber union to connect the vacuum source directly to the combined unit. The outlets are at a 90 degree angle instead of the 45 that the OEM units have. I haven't tried to fit it in the car yet, but 90 degree rubber elbows might be needed to alleviate strain on the vacuum lines. I'll have to test fit it to see. It does not come with a mounting rail. However, it has tabs that stick out to the sides of the valve bodies, so it will be easy to mount to a flat piece of metal and there will be no risk of screwing into the solenoid wrapping. Right now, I think that this is my best version. It takes a little bit of assembly work, but nothing harder than taking off the interior panels and removing the factory assembly.

Another benefit of the last type (#3) that plug into each other is that if one fails, it's easy to replace just one of them, instead of needing an entirely new assembly. And, you can easily set it up for less or more valves if you have done something different with your car. But, you would need to replace all of the factory valves. They won't work with the factory rubber manifold.

I'll get around to bench testing it and test fitting it in the car a little later this week. Dimensionally, it looks to be about the same as the OEM unit, except a little bit shorter.

If they do ok on the bench, I'll install it n the car.

I don't know if any of these versions are going to interest other people, but I'm comfortable that I've now got a way to replace all of my HVAC vacuum solenoid valves with brand new valves for a fraction of the price of buying five used ones.
User avatar
By Shifted
Good news. The valves work properly, draw very little current, and heat up less than the original valves.

The executive summary is: these valves should be a near drop in replacement for the whole OEM HVAC vacuum solenoid assembly (all five must be replaced to use these new valves). They are a fraction of the cost of used OEM valves. The mounting can be figured out by the end user, or they can be pre-mounted and wired for easy installation.

Below are some photos that show their dimensions. The new solenoid is much bigger than the factory solenoid. But the overall size, when including the vacuum connections and manifold, is similar. These valves build their own manifold as you connect them together. Which means that they end up being a little shorter than the OEM valves with the OEM manifold, and you don't have to replace the OEM manifold if it's leaking or torn.

The valves operate just like the OEM valves. They vent out of the bottom when off. They are not current direction sensitive, so you can hook up either wire to ground(-) or power(+). The OEM valves heat up quite a bit, so I was worried that these bigger solenoids might heat up even more. I've hooked one of them up to a 13.8v power supply and will leave it powered up for two hours. I'll check the operation at the end of that period and also check the temperature of the body. I've hooked up an OEM valve in parallel so that I can compare its temperature to the new valves. After about 5 minutes, the OEM valve was at 90 degrees, and the new valves were are 75.

If the valve passes the 2 hour temperature and operation test, I'll install the unit of five in my car.

Yes, you can find the manufacturer if you want to. There's no secret there. But, please don't do that quite yet. They've been accommodating so far, but eventually they will tire of doing sample orders in such small quantities, and that bridge might get burned. My hope is that these valves will work out and it will make sense to place a large enough order for them that the manufacturer considers doing on-going business with "us" to be worth it.

I do have five more of these valves in case someone else has an urgent need for them.
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User avatar
By Shifted
After 2 hours being powered on, the new one was about 120 degrees, and the OEM valve was about 150. It depends on where you get the temperature from, but even just by feel the OEM one was much hotter.

Operation was the same as when I started.

I'm out of time for the day, so the installation will have to wait for another day.
User avatar
By Shifted
I took the above assembly and wired it up. Then, I installed it in the car. Sort of. It's pretty bulky and almost impossible to mount up in the same place as the OEM valves. Additionally, the orifices are bigger than OEM, so connecting them to the stock plumbing is difficult (but possible). I would consider that assembly "possible, but not ideal".

Since I wanted to move on to other projects and close the center console back up, I decided to try the valves described in my earlier post as option #1. Photo below. They have the right size ports, with barbs on them. They slip right into the stock manifold. Add a couple of terminals to the new valves, and they wire right into the OEM wiring harness and mounting rail. The one thing that I did not do is make "L" brackets in order to solidly mount them to the OEM rail. Due to the barbs, they aren't going anywhere, but it's not really an ideal mounting. I just ran out of time.

I put everything back together and ran the car for about 30 minutes, and everything works great. No leaks, all flaps function properly.

When I have some free time, I'll make up a couple of brackets with the right dimensions and hole placements. That will make it a very simple plug and play solution.

I purchased these particular valves through eBay. So, there is no relationship with a manufacturer for these. Anyone can buy them and come up with their own mounting/wiring solution. If a bunch of these were to be purchased for resell, then it would make sense to buy them directly from the manufacturer for a better price and support.

Is there enough demand for this to warrant making up more brackets and putting together a bunch of replacement units? Or is this only useful to me?
User avatar
By Shifted
Absolutely: https://www.ebay.com/itm/DC-12V-2-posit ... 3142317739

In case that link dries up, the keywords to search for are "12v 2-position 3-way air valve". That will net you lots of results that are in the right ball park.

These specific valves have two threaded mounting holes on one side of the body. The outlet doesn't face the same way as the OEM valves. I need to do a little measuring and experimentation to see if a 45 degree bracket could place the valve in the same place as the OEM valves on the rail, but with the outlet at the stock 45 degree angles. If not, having the outlet sticking straight out should work fine, especially if a longer rubber connector is used.
User avatar
By jschiller
Thanks for the link! I don't need the valves but they are priced so good it wouldn't hurt to have a few on hand for the future. That's when I'll worry about how to mount them :joy:
User avatar
By Shifted
Took a couple of hour drive yesterday and the valves worked great. No issues. I consider this an acceptable alternative.

Since no one has expressed any significant interest in this, I'll just drop it. The information is here, though, in case someone wants to buy and install their own valves.
User avatar
By Landseer
I think it's another extremely useful thread, breaking new ground. During winter I intend to use it to fix brown car.

So far, in 13 years of ownership, I've never had one with properly working hvac. Really want! I have new diaphragms. Going to see if I can order these solenoids now preemptively. Need fan too, then.

Much appreciated, very well described.
User avatar
By Shifted
Glad that it's useful :) In that case, maybe I'll sort out the L brackets and proper mounting screws.

Was it the trip to Atlanta in the middle of the summer (and the Atlanta rush hour traffic) with no A/C? Those are how lasting memories are made!
User avatar
By Landseer
Yup. Along with the squeaking brakes. And cracked tires. It seemed to run well at speed. But really hot in cabin. And vac leak was killing my low end pickup.

Little by little. Have a place to work finally.
User avatar
By Shifted
Having a place to work on it will make things very nice! A shame that you're not local anymore. Maybe I'll see you again at Amelia or Frenzy next year.
User avatar
By jschiller
Shifted: I've got 5 of these on order so I'd love to see how you mounted them. Alternatively, if you are going to producing the mounting brackets, I'd take a set.
User avatar
By Shifted
Right now, the two that I installed are just plugged into the OEM rubber vacuum manifold and not solidly mounted to the rail. I added a ring terminal to the negative wires on the valve and sandwiched that between one of the OEM valves and the mounting rail. And put blade connectors on the other wires to plug into the OEM power connectors. The blade connectors needed to be trimmed to fit in the OEM connectors, so you may want to experiment with that before you crimp them onto the valve wires.

For a mount, what I would like to do is get a length of angle iron and cut it up into a series of right angle brackets. Add holes on one side to match the valve holes. And add a hole, and tap it, to accept the factory mounting screw through the factory rail. It should be pretty straight forward. However, now that my dash is back together, it might be awhile before I get to it.

I think that a proper "kit" would have a valve mounted to the angle bracket with the terminals already crimped on and ready to just plug in.

It's not very hard to execute and would make a fun little winter fabrication project to knock a bunch of them out. I'll look around and see if I can get ahold of an OEM mounting rail without the valves. That would give me enough to make everything without having to take my dash apart.

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