Dash disassembly - Vacuum Generator issues

Topic: Dash disassembly - Vacuum Generator issues (Read 915 times) previous topic - next topic

Dash disassembly - Vacuum Generator issues

February 19, 2014, 06:14:31 pm

My vacuum generator started tit-tic-tic-ing some years ago, and someone told me I needed to replace it with a $250+ new one. I just disconnected it, which causes the vent air-flow to default to the defrost vents.

I had a friend find me one in his travels, but it responded with the same tic-tic-ing, so now I think perhaps it is an air leak somewhere. I searched the forum and know we have had this issue talked about, as well as the replacement Ford pump...but before I go that route, I would like to track down the valves and see if I just have a little leak in a hose somewhere.

Where are all the spots that I should check? Is there an easy procedure where I can just apply 12 volts to the pump from an external battery and check the system for leaks?

I have 2/3rds of the dash off of the top, but I still don't see where the vent control aparatus is located. I thought I had seen a dash disassembly topic here, but can't seem to find it today.

This is a 2002, and I don't know which years are similar. Alternatively, I suppose I could wire it up to open the dash vents instead of defaulting to defrost when the generator is unplugged.

Thanks!

Re: Dash disassembly - Vacuum Generator issues

Reply #1 – February 19, 2014, 06:19:47 pm

Quote from: Brad & Christine Slaughter – February 19, 2014, 06:14:31 pm

I have 2/3rds of the dash off of the top, but I still don't see where the vent control aparatus is located. I thought I had seen a dash disassembly topic here, but can't seem to find it today.

Here's one from Jim McNeece in case it helps

2003 U-320 What type of Aqua-Hot HX is in the dash - Cozy or Komfort or

Re: Dash disassembly - Vacuum Generator issues

Reply #2 – February 19, 2014, 06:23:29 pm

And some from Peter M.

Dash A/C Again - 97 U270

Re: Dash disassembly - Vacuum Generator issues

Reply #3 – February 19, 2014, 06:42:24 pm

Thanks, Michelle. The pictures from Jim's 2003 look identical and I have found the vacuum pieces (whatever they are) behind the center console.

I had thought that nothing was working, but what is happening when I turn the key on (with the generator plugged back in) is as follows:

The dash switch works fine to direct the airflow...exactly as it should. But then about 5 seconds later, the vacuum pump goes tit-tic-tic very rapidly and does not stop. When I turn the key off, then back on, the situation repeats itself: Works as it should for 5 seconds, then starts clicking.

I'm thinking there really isn't any leak in the dash as all looks well there and there is no noise. Is it possible that the big "soup can" leaks and that is the problem? Or maaybe what looks like a check valve in the line coming from the pump? It really puzzles me that it does pull the vents as it is supposed to...but still makes the racket.

Ideas? After the slide hydraulics, this should be a piece of cake! (I hope)

Re: Dash disassembly - Vacuum Generator issues

Reply #4 – February 19, 2014, 08:28:29 pm

Brad,

Have you examined the vacuum generator under the step to observe the problem? One time the line rubber line was dry and cracked....easy, If your generator actually has failed, you might consider a $50 used electric vacuum pump from an automobile - via an auto junk yard. Laugh as you may, that has works very well for a lot less money.

Re: Dash disassembly - Vacuum Generator issues

Reply #5 – February 19, 2014, 09:08:14 pm

Use something like a vice grip and start at the pump and work away until you find the leak. Hemostats are the best. Vacuum pumps are not expensive and available on eBay but you probably don't need a pump.

On GVs, remove the hidden screws in the carpet on the wall in front of the passenger's seat. Don't know about later models.

Took me about an hour to find my problem.

Pierce

Re: Dash disassembly - Vacuum Generator issues

Reply #6 – February 19, 2014, 09:23:35 pm

So. There are several hoses that come out of the little vacuum generator. I think 3? One or two go to the can, and I think one goes elsewhere. It sounds like I need to grip each one and when I block the *right* one, the ticking will stop? And that is probably the main hose headed to the valves under the dash? And then if I follow that, I should find a leaky hose somewhere?

I saw a picture somewhere here of someone having repaired a leak in the can. Is that can a vacuum "storage" tank?

I tried to google vacuum generator to understand exactly what is going on in the system, but all I can get is that a vacuum pump uses a venturi to create a vacuum. I still don't understand whether this thing is electric operated or air operated.

I guess what I need is a picture to understand the air and vacuum flow, akin to an electric schematic! Sorry to be so dense with this one.

Re: Dash disassembly - Vacuum Generator issues

Reply #7 – February 19, 2014, 09:25:12 pm

Quote from: Jim Frerichs – February 19, 2014, 08:28:29 pm

Brad,

Have you examined the vacuum generator under the step to observe the problem? One time the line rubber line was dry and cracked....easy, If your generator actually has failed, you might consider a $50 used electric vacuum pump from an automobile - via an auto junk yard. Laugh as you may, that has works very well for a lot less money.

I wouldn't laugh. I'm just trying to understand how it works and then what to actually buy...if more than a hose needs to be replaced.

Re: Dash disassembly - Vacuum Generator issues

Reply #8 – February 19, 2014, 09:55:16 pm

It is a electric vacuum pump. Have been replacing them in aircraft and diesels since the 60's and never seen them referred as anything but a vacuum PUMP except on the forum. The "can" is just a vacuum reservoir. Finding a leak is just the opposite of finding a air leak in a hose. Just easiest to start at the pump and work out from there. If you clamp the hose and the pump stops, the leak is further away. Just keep moving outward.

Pierce

Re: Dash disassembly - Vacuum Generator issues

Reply #9 – February 19, 2014, 10:08:33 pm

You might try moving the sliding the temperature selector to the right a half inch if you have a Ford control. That was our problem. They are prone to leaks in the far left position.

Pierce

Re: Dash disassembly - Vacuum Generator issues

Reply #10 – February 19, 2014, 10:10:06 pm

Mine is different than that. No slide controls in a 2002. Is this a replacement pump? 12 Volt Vacuum Pump: Amazon.com: Industrial & Scientific

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Dash disassembly - Vacuum Generator issues

Reply #11 – February 19, 2014, 11:31:42 pm

Yes, but looks like it may be on the small side. They are rated in CFM standing for cubic feet per minute. If you are sure your pump is bad, look at the data plate on it and buy one with around the same rating. Your pump should operate when the key is turned on (run) position. You should look off one with fittings something like yours so you don't spend all day at the hardware store buying adapters.

Only a few Diesel engines have throttle butterfliesand without one, it is impossible to generate a vacuum so a pump has to be fitted somewhere. Aircraft use them to spin gyro instruments like artificial horizons, gyro compass, etc. Vacuum pumps are also used to evacuate the air from AC units before charging with refrigerant.

The only thing likely to make your pump fail is a large enough vacuum leak so the pump runs all the time and overheats, fails. If your not in a hurry, order several hemostats off eBay and start clamping off hoses.

If you get stuck, PM me.

Pierce

Re: Dash disassembly - Vacuum Generator issues

Reply #12 – February 19, 2014, 11:38:31 pm

Thanks, Pierce. I think I have enough to get started tomorrow. Am I right to assume that if the thing works when I first turn it on...and moves the air deflector valves to the different locations and holds them there while it starts ticking...that this is a good indicator that my pump actually works and it definitely is just a leak somewhere?

Re: Dash disassembly - Vacuum Generator issues

Reply #13 – February 20, 2014, 12:07:01 am

Yes

P

Re: Dash disassembly - Vacuum Generator issues

Reply #14 – February 20, 2014, 12:12:34 am

I just took another look at the vacuum thing. It is fed by air, it looks like. The air goes into the hole in the side. Is this a different critter on my 2002?

Re: Dash disassembly - Vacuum Generator issues

Reply #15 – February 20, 2014, 12:28:47 am

I first noticed our problem when the pump came on every couple minutes. I could hear it while driving. It was annoying and also worrisome. Worked out from the pump until I got to the Ford control and while moving the slide control, the pump stopped. Lucky.

The pump has a vacuum switch that shuts off the pump when a certain amount of vacuum is reached.

Watching the Olympics with iPad in one hand so my answers may be not too coherent.

One port is suction and the other is discharge, in other words, discharging any air from leaks or normal air evacuation operation.

Pierce

Re: Dash disassembly - Vacuum Generator issues

Reply #16 – February 20, 2014, 12:51:52 am

Your photo just came up on my iPad. The pump is exactly like sucking up a milk shake with a straw. The straw in this case is a hose. The pump comes nowhere near a perfect vacuum but drops the pressure enough so the pressure differential is sufficient to operate/move the air deflector valves.

P

Re: Dash disassembly - Vacuum Generator issues

Reply #17 – February 20, 2014, 07:58:19 am

Brad,

I would think almost any vacuum pump would work as long as a12 volt shut-off is working.

Jim

Re: Dash disassembly - Vacuum Generator issues

Reply #18 – February 20, 2014, 07:21:32 pm

I managed to get mine working by replacing the metal can with a plastic one from the junkyard pump set, then I replaced one of the hoses that seemed likely to be leaking. Presto, I believe it is working properly. Just another case where I listened to someone tell me that "when they start clicking, they are dying and you need to spend another $250". The clicking just seems to be the vacuum not quite up to what it needs to be, a result of a leak somewhere, not really a failing $250 pump.

Thanks to some offline help, I think I understand it better now and have ordered a -70Kpa pump from ebay to see how well converting to electric might work. It was a couple of bucks more than the -50 kpa pumps, but it was still only $18.24 delivered from Minnesota.

Re: Dash disassembly - Vacuum Generator issues

Reply #19 – February 20, 2014, 08:23:16 pm

Quote from: Pierce & Gaylie Stewart – February 19, 2014, 09:55:16 pm

It is a electric vacuum pump.
...
Pierce

My 2002 uses AIR to operate the pump. They didn't use an electric pump for this particular year, but I may well end up changing it to electric.

Re: Dash disassembly - Vacuum Generator issues

Reply #20 – February 21, 2014, 09:19:26 pm

Quote from: Brad & Christine Slaughter – February 20, 2014, 08:23:16 pm

My 2002 uses AIR to operate the pump. They didn't use an electric pump for this particular year, but I may well end up changing it to electric.

Brad,
Replacing the air to electric one:
Dash Air Vacuum Generator

Re: Dash disassembly - Vacuum Generator issues

Reply #21 – February 21, 2014, 11:07:00 pm

Quote from: Brad & Christine Slaughter – February 20, 2014, 08:23:16 pm

My 2002 uses AIR to operate the pump. They didn't use an electric pump for this particular year, but I may well end up changing it to electric.

Quote from: Barry Beam – February 21, 2014, 09:19:26 pm

Brad,
Replacing the air to electric one:
Dash Air Vacuum Generator

Thanks Barry. I think the little pump I bought from ebay may need to have me incorporate the switch from the old one in order to turn it off when max pressure is reached, but I don't have it yet to try it. Since I have an extra complete unit, I will hook it all up to an external battery first to check it all, then add the switch if it won't shut off by itself. Then I'll report here if I really have found a less-than-$20 solution. So far, the changes I made have the old air pump working fine.

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