Dash Air Stuck on Defrost/Vacuum Pump Replacement

Topic: Dash Air Stuck on Defrost/Vacuum Pump Replacement (Read 2674 times) previous topic - next topic

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #25 – January 18, 2021, 03:03:27 pm

Craneman,

I probably should have done the same as you. However, I had already bought a 12 volt vacuum generator and I destroyed the metal box which contained the guts of the original vacuum generator.

Richard

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #26 – September 23, 2021, 10:50:22 pm

Elliott and hdff

I did this today, thank for the write up. When I turned on the ignition, it was a whomp whomp coming from the pump. How does your sound? Mine did not sound right, I wonder if I got a bum pump?

Side note, the fitting on the back side that has the air hose has been a bear to remove. I had to take the regulator off, put it in a vise and I still cannot remove it with a pipe wrench,, guessing the PO put on some loctiite or something. I will try more tomorrow. Not that I am too disappointed, the regulator gauge is shot so I am going to replace regualtor too. I am chasing an air leak so hope a new regulator may fix it.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #27 – September 24, 2021, 10:22:05 am

Quote from: Jason – September 23, 2021, 10:50:22 pm

Elliott and hdff

I did this today, thank for the write up. When I turned on the ignition, it was a whomp whomp coming from the pump. How does your sound? Mine did not sound right, I wonder if I got a bum pump?

Side note, the fitting on the back side that has the air hose has been a bear to remove. I had to take the regulator off, put it in a vise and I still cannot remove it with a pipe wrench,, guessing the PO put on some loctiite or something. I will try more tomorrow. Not that I am too disappointed, the regulator gauge is shot so I am going to replace regualtor too. I am chasing an air leak so hope a new regulator may fix it.

Regarding the womp womp: no. Mine is a constant fast waaaaa. Like an air compressor.

Check the air cylinder that moves the step cover too. It's known to leak where the arm exits the tube. I'm getting ready to put a solenoid in line to those regulators you mention because that whole corner of the coach is known to be problematic

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #28 – September 24, 2021, 06:37:46 pm

Thanks Elliot. I looked at this again. Between the hose going from the pump to the new Dorman amplifier, I put in the check valve that hpff showed. This caused womp womp. With it removed, the pump ran like a compressor for a time, then cycled off and on as it should. I have double checked the valve ensure it is going the right way, but I am confused why the valve would do this? Is a check valve needed?

I will be looking forward to when you do the solenoid!

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #29 – December 24, 2021, 07:20:41 pm

My vacuum pump was shot so I have a new one. My problem is one of the control
valves is leaking. Does anyone know what they are out of.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #30 – December 25, 2021, 10:31:09 am

If you have the slider on the heater/AC control, the leak may be when the slider is in the far left position. I put a small stop on ours so it blocks the last quarter inch. Otherwise, the vacuum pump ran all the time.

Pierce

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #31 – December 25, 2021, 10:54:30 am

I have found the control valve that is leaking and it leaks most in the defrost position.
The pump doesn't run steady. It burps about every 5 seconds. So I would like to
know if anyone knows other equipment that they were installed in.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #32 – December 26, 2021, 10:38:51 am

FOT had both the actuators and the solenoid valves in stock.

Rich

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #33 – December 26, 2021, 11:04:22 am

Thanks Rich if I can't find it locally I will try Foretravel.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #34 – December 26, 2021, 11:27:59 am

Quote from: oldguy – December 25, 2021, 10:54:30 am

I have found the control valve that is leaking.
I would like to know if anyone knows other equipment that they were installed in.

You probably already know this, but just in case, I have had good luck searching for mystery coach components by:
1. Removing the component and seeing if it has ANY kind of ID number.
2. If ID number present, searching that number with Google.
3. If ID number missing, doing a Google search for the best physical description I can come up with, for instance:
"vacuum heater control valve".
4. When Google returns results of search, go to the "Images" category, and compare the pictures to what you have on hand.
5. You may not hit gold on the first pass, but you can always refine your search parameters and try again. It often works for me!

vacuum heater control valve - Google Search

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #35 – December 26, 2021, 11:53:36 am

Thanks Chuck, there is a number 2-27106 but I couldn't find anything with it. I went
through what you sent, no luck. I'm trying to find what I need in Canada as the courier
companies are charging big brokerage fees. I paid more for shipping on something I
bought than I did for the item. When the border is stable I will go back to shipping
items to Point Roberts and go there to pick up the items.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #36 – December 26, 2021, 12:18:10 pm

Quote from: oldguy – December 26, 2021, 11:53:36 am

Thanks Chuck, there is a number 2-27106 but I couldn't find anything with it.

Post a few sharp photos of the doohickie, and also the front view of your A/C/heater control panel. I'll try my luck at searching.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #37 – December 26, 2021, 04:51:10 pm

I found a photo of the climate controls on a '99 U320 (see below). Is this the same as your coach?

I was looking around online and found reference to Evans Tempcon being the manufacturer for many RV climate control systems. Found the website linked below. The photos of the control panels they sell show control knobs that look very similar to the ones in the photo.

If you don't have luck anywhere else, you might try contacting Comfort Air to see if they can help with parts or information.

HVAC Control Panels - Evans Tempcon - Comfort Air Inc. -

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #38 – December 26, 2021, 04:59:01 pm

Chuck the second picture is the item I am looking for.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #39 – December 26, 2021, 05:57:51 pm

I downloaded this and refer to it often https://www.foreforums.com/index.php?action=media;sa=album;in=593 it's the parts manual for a 2000 and 2003. Your 99 will most likely be the same as the 2000.

Look at page 252-253, it's section 1280 .

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #40 – December 26, 2021, 07:30:05 pm

I'm having a similar issue where sometimes I can turn the A/C on and it will come out of the dash but after some time, it will switch to the defrost or floor on it's own. Sometimes I can turn it on and it won't go to the dash, only defrost or floor.

It looks like I have the same setup that Elliott posted. Mine is mounted to the passenger side of the generator box. Today I pulled the check valve out and put it on my Mighty Vac. It will hold 15in-Hg for 15 mins, so I'm thinking it's good. Next I connected the Mighty Vac up to the vacuum canister and pulled 18in-Hg on it. It held that for at least 10 mins. Then I connected the Mighty Vac to the vacuum pump and let the pump run (key on). It was able to generate about 14in-Hg of vacuum, so I don't think my issue lies in this system.

Next I'll have to pull the dash apart and see if I have a leak in one of the lines from the solenoids to the dash vents. Maybe the line from the dash control solenoid to the actuator is leaking.

Does it sound like my reasoning is sound?

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #41 – December 26, 2021, 08:35:14 pm

Thanks Jason for the manual. The 2000 has 3 of the valves where the 1999 uses
4. I have downloaded the manual onto my labtop so thanks for it. I can never have
too many manuals.
Keith if you hold the vacuum in all the control valve switch, it could be an electrical
problem.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #42 – December 26, 2021, 08:42:22 pm

Old guy - your second picture is the solenoid valve.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #43 – December 26, 2021, 08:51:47 pm

Yes Rich and I have 4 and one of them is leaking. If I can't find a replacement in
Canada I will try Foretravel when I think the border is stable. I can live with just
the defroster working. I have a few other things that I need from Foretravel too.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #44 – December 27, 2021, 04:01:29 pm

Quote from: oldguy – December 26, 2021, 08:35:14 pm

Keith if you hold the vacuum in all the control valve switch, it could be an electrical
problem.

Got the dash opened up and did some poking around. Vacuum holds fine...turns out I appear to have a vacuum solenoid on the fritz. It works intermittently, even though 12V is applied when dash air is called for. Now I need to figure out where I can get one of these little guys. Any ideas guys?

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #45 – December 27, 2021, 05:04:43 pm

Quote from: WS6_Keith – December 27, 2021, 04:01:29 pm

I appear to have a vacuum solenoid on the fritz. Now I need to figure out where I can get one of these little guys.

"Where to get a solenoid?" That's been the subject under discussion for the last 3 days. Go back and start reading this thread from Reply #29.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #46 – December 27, 2021, 07:50:40 pm

As Rich said try Foretravel

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #47 – December 28, 2021, 11:25:42 am

Foretravel has a replacement. It's not the same as the original and may need to be mounted differently, but it is available for $25 each. Ordered one this morning from Brad.

Re: Dash Air Stuck on Defrost/Vacuum Pump Replacement

Reply #48 – October 12, 2024, 06:07:17 pm

Thanks Elliott for the write up. Did this update with very little effort and works perfectly.

Affiliate Notice