Vacuum switch for dash AC controls.

Topic: Vacuum switch for dash AC controls. (Read 2641 times) previous topic - next topic

Vacuum switch for dash AC controls.

July 03, 2018, 09:47:34 am

Not having any luck with the search for a new vacuum switch that controls the 12v vacuum pump for the dash AC controls. It's made by CH - Eaton and has one set of NC contacts and an adjustable cut in / cut out setting.

Ours malfunctioned on this last trip and I had to jumper it out to get AC to blow thru the dash vents. Of course this meant the pump had to run continuously (probably not the best for it) but it got us home and didn't "smoke"

Anyone have a source for a replacement?

Re: Vacuum switch for dash AC controls.

Reply #1 – July 03, 2018, 01:46:43 pm

Are you referring to the switch under the step or one in the dash?

Re: Vacuum switch for dash AC controls.

Reply #2 – July 03, 2018, 02:21:25 pm

Johnnys's A/C Parts Warehouse in Warren, Arkansas is a good source for hard to find A/C parts. They just might have it.

RV Motorhomes - Johnny's AC Parts Warehouse

Jerry

Re: Vacuum switch for dash AC controls.

Reply #3 – July 03, 2018, 02:54:36 pm

Quote from: FourTravelers – July 03, 2018, 09:47:34 am

Not having any luck with the search for a new vacuum switch that controls the 12v vacuum pump for the dash AC controls. It's made by CH - Eaton and has one set of NC contacts and an adjustable cut in / cut out setting.
Ours malfunctioned on this last trip and I had to jumper it out to get AC to blow thru the dash vents. Of course this meant the pump had to run continuously (probably not the best for it) but it got us home and didn't "smoke"

Our firewall mounted vacuum pump ran all the time until I discovered the Ford AC/heat control slide lever has to be about a quarter inch to the right of the left stop. Otherwise, there is a vacuum leak and the pump runs all the time. Pretty easy to clamp hoses until the offending part is found if not the Ford control. Several others have had the same problem with the slider.

Pierce

Re: Vacuum switch for dash AC controls.

Reply #4 – July 03, 2018, 03:08:48 pm

Beware of this one at Johnny's and other places;

030-00043 - Johnny's AC Parts Warehouse
Amazon.com: Dorman 904-214 Mechanical Vacuum Pump for Ford Truck: Automotive

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

Re: Vacuum switch for dash AC controls.

Reply #5 – July 03, 2018, 03:14:34 pm

Beware OR Be aware?

Re: Vacuum switch for dash AC controls.

Reply #6 – July 03, 2018, 03:25:51 pm

Re: Vacuum switch for dash AC controls.

Reply #7 – July 03, 2018, 03:30:50 pm

I have no experience with that vacuum pump-- understand it us used on many Ford diesel trucks.

What is the issue with it? Need to add to my knowledge base.

Re: Vacuum switch for dash AC controls.

Reply #8 – July 03, 2018, 03:44:26 pm

Lots of different 12V vacuum pumps will work. Ebay has a lot listed. Read specs before ordering.
12v vacuum pump | eBay
Pierce

Re: Vacuum switch for dash AC controls.

Reply #9 – July 03, 2018, 03:55:24 pm

Quote from: wolfe10 – July 03, 2018, 03:30:50 pm

What is the issue with it?

The price difference between the two vendors is all.

Re: Vacuum switch for dash AC controls.

Reply #10 – July 03, 2018, 03:59:17 pm

The switch that controls the 12v vacuum pump is mounted on the front firewall just to the right (driver) side of the AC condenser coils. It's next to the vacuum accumulator bulb. The vacuum line runs from the pump to a "T" then to the accumulator then to the line that runs thru the firewall inside to the controls. The switch "t"s into this line and it's NC contacts control the relay that runs the pump. It has "cut in" and "cut out" settings. It use to cut in at 6" hg and cut out about 12"hg. The switch no longer will "close" the contacts. They check open all the time. With no vacuum they should be closed.
I'll post a pic of the switch tomorrow. It's still mounted to the coach.

Re: Vacuum switch for dash AC controls.

Reply #11 – July 06, 2018, 10:37:17 pm

Here are a couple of photos of the vacuum switch that I'm looking for.
If anyone has replaced theirs? I would appreciate info on

Re: Vacuum switch for dash AC controls.

Reply #12 – July 07, 2018, 07:38:41 am

Different part number but maybe give them a call
http://www.nwrvsupply.com/05-03/9533N524V.html

I also found a Ranco 4103028
Motorhome Dash AC and Heat systems

I would think there would be enough range in adjustment for your application. Or Contact Ranco with the original Cutler Hammer Eaton number and see if they can cross it. Not much coming up on the web.

Re: Vacuum switch for dash AC controls.

Reply #13 – July 07, 2018, 08:22:10 am

Quote from: stump – July 07, 2018, 07:38:41 am

Different part number but maybe give them a call
http://www.nwrvsupply.com/05-03/9533N524V.html

I also found a Ranco 4103028
Motorhome Dash AC and Heat systems

I would think there would be enough range in adjustment for your application. Or Contact Ranco with the original Cutler Hammer Eaton number and see if they can cross it. Not much coming up on the web.

Thanks Stump
I'll try Northwest RV Supply, It should work, it's adjustable and has NC contacts.
Sure not many sources of these out there...........
maybe I should get a spare? but then again, this one has lasted over 20 years.

Re: Vacuum switch for dash AC controls.

Reply #14 – July 07, 2018, 09:42:21 pm

Quote from: FourTravelers – July 07, 2018, 08:22:10 am

Thanks Stump
I'll try Northwest RV Supply, It should work, it's adjustable and has NC contacts.
Sure not many sources of these out there...........
maybe I should get a spare? but then again, this one has lasted over 20 years.

Stump is correct! I had to replace mine last year when I removed it checking for vacuum leaks and broke the copper tube coming out of the switch. I got one from Billy Jack at FOT. The part NO. is 9533N524V Switch N/C Vacuum.

A great source for troubleshooting the HVAC system is Evans Tempcon. Evans Tempcon > Troubleshooting, Diagnosis and Repair

Their vacuum schematic diagram for the slide control has different tube color indicators than on my system. However, it will give you a good place to start if you need to trace where the different colored tubes go from the head to the harness and the various doors. http://www.evanstempcon.com/pdf/scs/logicdiagram.pdf

I had a vacuum leak coming from a rusty vacuum motor on the fresh air door mounted on bubble unit. The white vac line going to it from the harness through the firewall was also leaking . If there is a vacuum leak there it will run the 12v pump continuosly if the slider control is on MAX AC/RECIRC as Pierce discovered!

Replaced the vacuum pump and the section of leaky tubing and now it's working just fine on Max/AC! When you turn on the ignition before starting the engine you can hear the 12v pump run until vacuum is achieved and then it should shut off after about 10 seconds. It should work like that for any position on the slide control. Mine will hold vacuum for about 20 minutes if I don't push any of the buttons which activate the vacuum motors for the doors.

The picture shows the repair. Notice the white vac line that comes out of the firewall with black rubber connector and new black hose that goes to the new vacuum pump. When I attach the vacuum motor back to the fresh air door it will open and close again.

Jerry

Re: Vacuum switch for dash AC controls.

Reply #15 – July 15, 2018, 07:50:23 am

Purchased the replacement vacuum switch from North West RV Supply. They only had two, and they were the only source found.
(Stump-thanks for your help)

Replaced the very hard to find vacuum switch yesterday, easy 5 minute job. After setting the cut in and cut out settings, the vacuum pump now cycles as it did before. Set to cut "on" at about 5"hg and cut "off" at 12"hg. It cycles every couple of minutes, so I'll try to determine where the leak is located, eliminating the dash controls first.

Re: Vacuum switch for dash AC controls.

Reply #16 – July 15, 2018, 02:13:02 pm

Quote from: FourTravelers – July 15, 2018, 07:50:23 am

Purchased the replacement vacuum switch from North West RV Supply. They only had two, and they were the only source found.

Seems that source has dried up - they are now showing "Out Of Stock".

Re: Vacuum switch for dash AC controls.

Reply #17 – July 15, 2018, 08:29:47 pm

I have a used one that as far as I know is good.

Re: Vacuum switch for dash AC controls.

Reply #18 – July 15, 2018, 10:08:01 pm

Quote from: red tractor – July 15, 2018, 08:29:47 pm

I have a used one that as far as I know is good.

Hang on to it! They are scarce as hen's teeth...........
I tried many Diesel truck shops, RV shops, O'Reilly's and NAPA's in Utah and Colorado with zero luck.
Drove home with it jumped out, hoping not to burn out the pump.

Re: Vacuum switch for dash AC controls.

Reply #19 – July 15, 2018, 11:13:29 pm

Been using the Ford Pump for several years, it has a built in switch, seems to work fine.

Re: Vacuum switch for dash AC controls.

Reply #20 – July 16, 2018, 05:29:52 am

Quote from: NancyS – July 15, 2018, 11:13:29 pm

Been using the Ford Pump for several years, it has a built in switch, seems to work fine.

If you could provide a model or part number on the one you use? Might be helpful to another member some day...........

Re: Vacuum switch for dash AC controls.

Reply #21 – July 16, 2018, 08:17:07 am

Quote from: FourTravelers – July 15, 2018, 07:50:23 am

Replaced the very hard to find vacuum switch yesterday, easy 5 minute job.

Excellent photos to go with your "find the part and install it" thread. Good photos add great value to a narrative.

That new (old stock) switch looks like it was fabricated by hand in a blacksmith shop!

I would be curious to see what the inside looks like. Care to do an autopsy on the old deceased switch?

Re: Vacuum switch for dash AC controls.

Reply #22 – July 16, 2018, 09:33:14 am

Quote from: FourTravelers – July 16, 2018, 05:29:52 am

If you could provide a model or part number on the one you use? Might be helpful to another member some day...........

Pump is Dorman 904-214

Re: Vacuum switch for dash AC controls.

Reply #23 – July 16, 2018, 11:59:24 am

Next rainy day that I am held up in the shop......
I'll dissect it and post some photos on this thread. I have had it partially dissembled already, in a vain attempt to repair it while on the road. Only so much you can do on a campground picnic table, any more will require a dremmel tool or grinder.

Re: Vacuum switch for dash AC controls.

Reply #24 – November 03, 2018, 07:28:30 pm

Dash control leak is common on the Ford AC/heat controls. Move slider a quarter inch to the right of the left stop and it should stop. Otherwise, the vacuum pump will run much of the time and burn out.

Pierce

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