My HWH compressor problem

Topic: My HWH compressor problem (Read 2345 times) previous topic - next topic

My HWH compressor problem

December 07, 2017, 08:16:22 pm

I'm having problems with my 12v hwh compressor in the basement. Replaced so far bowl and solenoid drain on bowl and pressure switch. My problem is the compressor will run and build pressure up to about 65# pretty quickly but will go no higher and continues to run. I unplugged the compressor and the pressure drops to 35# pretty quick. I tried closing the 1/4 turn on the small black tank to see if that would help, no change. Any suggestions on what to check next? Also I; the 2nd pic what is that silver round thing attached to the air tubing?

Re: My HWH compressor problem

Reply #1 – December 07, 2017, 09:14:35 pm

Keith, the second picture shows a check valve. Let's air move in one direction only. It sounds like you have air leaks somewhere. Could be that check valve or another one. Have you done the soap test on your air lines and fittings?

Re: My HWH compressor problem

Reply #2 – December 07, 2017, 10:07:19 pm

I sprayed the ones at the air tanks,front and back,I haven't sprayed the ones around this compressor. Just sitting it passed a leak down test I did BUT going down the road both dash gauges go from 115 to 90 where they start refilling! In about 1minute 30 seconds. That seems fast to me and I don't know if that correlates with this issue

Re: My HWH compressor problem

Reply #3 – December 07, 2017, 10:17:01 pm

Quote from: hdff – December 07, 2017, 10:07:19 pm

I sprayed the ones at the air tanks,front and back,I haven't sprayed the ones around this compressor. Just sitting it passed a leak down test I did BUT going down the road both dash gauges go from 115 to 90 where they start refilling! In about 1minute 30 seconds. That seems fast to me and I don't know if that correlates with this issue

Had the same problem, load to unload in about 95 seconds, found both protection valves and one check valve leaking. Make sure you test on fairly good road, on rough road, bags dump and fill often. Check valves under coach will keep you aux comp from filling main tanks, if either or both leak by, they will try to use little comp to fill all tanks. Check your air diagram, you will see the flow from the aux comp to hwh valves
If those check valves are bad, the leak through valve and you will not see bubbles on outside.

Re: My HWH compressor problem

Reply #4 – December 07, 2017, 10:26:19 pm

I guess I need to figure out where all these check valves are and how to check them...... where would I find this info? I have a lot to learn!!! Leak down is the same on all roads, city roads,i45,i10 or 59/i69

Re: My HWH compressor problem

Reply #5 – December 07, 2017, 10:31:46 pm

Quote from: hdff – December 07, 2017, 10:26:19 pm

I guess I need to figure out where all these check valves are and how to check them......

The check valves under the coach are just like the one by your aux comp in your picture. Not too hard to check, air should only go through one way, but a pain pulling them out.

Re: My HWH compressor problem

Reply #6 – December 07, 2017, 10:59:13 pm

Quote from: hdff – December 07, 2017, 10:26:19 pm

I guess I need to figure out where all these check valves are and how to check them...... where would I find this info?

The info is on your air system schematic. The thread below might help you in deciphering:

Air System Schematic Symbols.

Coach Air System Information and Guides [ForeForums Foretravel Motorcoach Wiki]

Re: My HWH compressor problem

Reply #7 – December 07, 2017, 11:35:15 pm

I had the same problem with air loss from 125 to 90 every 90 seconds or so. Turned out to be mu D-2 governor.

Re: My HWH compressor problem

Reply #8 – December 07, 2017, 11:39:24 pm

Fixing air leaks
MOT has them for about $40 ea.

Re: My HWH compressor problem

Reply #9 – December 08, 2017, 12:11:44 am

If you take out the check valves, might as well replace, NAPA carries, about $30 a piece.
Except the tiny one that is on the pump output

Re: My HWH compressor problem

Reply #10 – December 08, 2017, 11:03:48 am

Does the arrow indicate "direction of flow" on the check valve symbol? Just making sure.

Re: My HWH compressor problem

Reply #11 – December 08, 2017, 11:04:25 am

Quote from: Old Hippie – December 08, 2017, 11:03:48 am

Does the arrow indicate "direction of flow" on the check valve symbol? Just making sure.

yes

Re: My HWH compressor problem

Reply #12 – December 08, 2017, 11:22:40 am

Quote from: hdff – December 07, 2017, 10:26:19 pm

I guess I need to figure out where all these check valves are and how to check them...... where would I find this info? I have a lot to learn!!! Leak down is the same on all roads, city roads,i45,i10 or 59/i69

Howdy hdff, This print may help.
Good Luck, Dave A

Re: My HWH compressor problem

Reply #13 – December 09, 2017, 10:28:45 am

How many check valves are there? Looking at Chuck's info he posted I see 5,2 on each air tank, 1on the wet tank, plus the one at the 12v compressor making 6 total. Is this correct. If I pulled to check them I will probably replace them. On Dave's schematic, what are the check valves with 2 arrows in the box? A double check? Also I'm thinking about changing the Haldex dryer. It looks fairly easy to change using a factory Re manufactured unit. Just a few air hoses and the mount to the frame, am I seeing the whole picture. Where is the ID plate so I can get the model info off the old unit to get the new unit on site before I start.....

Re: My HWH compressor problem

Reply #14 – December 09, 2017, 10:42:08 am

Quote from: hdff – December 09, 2017, 10:28:45 am

How many check valves are there?

Where is the ID plate so I can get the model info off the old unit to get the new unit on site before I start.....

There should be a check valve at the inlet to each air tank, plus the one on your aux compressor. There are several other valves in the system that perform a dual function of check valve plus something else. For instance, the valve indicated by a box with two arrows is a 2-way check valve. It will allow flow from either of two directions, but only one at a time. It is used when there are two air sources for one device (or circuit). The air source with the highest pressure "wins" and air will flow from that direction to the device. See the schematic linked by Dave (Reply #12)

The ID plate is probably a metal tag on the base of the dryer. May also be a decal or sticker on the cartridge cover. Photo below is the AD-9 used on my coach. The metal tag on the base just has a part number, which can then be crossed over to the actual dryer model.

Re: My HWH compressor problem

Reply #15 – December 09, 2017, 10:44:51 am

Quote from: hdff – December 09, 2017, 10:28:45 am

How many check valves are there? Looking at Chuck's info he posted I see 5,2 on each air tank, 1on the wet tank, plus the one at the 12v compressor making 6 total. Is this correct. If I pulled to check them I will probably replace them. On Dave's schematic, what are the check valves with 2 arrows in the box? A double check? Also I'm thinking about changing the Haldex dryer. It looks fairly easy to change using a factory Re manufactured unit. Just a few air hoses and the mount to the frame, am I seeing the whole picture. Where is the ID plate so I can get the model info off the old unit to get the new unit on site before I start.....

Seeing you are disassembling all the piping for the check valves, might as well do the two protection valves as well. About same price as the check valves.

Re: My HWH compressor problem

Reply #16 – December 09, 2017, 11:39:44 am

Quote from: hdff – December 09, 2017, 10:28:45 am

Where is the ID plate so I can get the model info off the old unit to get the new unit on site before I start.....

Keith,

On a 2000 U-320 you should have a Haldex Pure air plus. Pure Air Plus™ Air Dryer - Haldex product category Make sure if you change out your dryer with a reman. unit to either install a new isolation valve or rebuild yours if your coach came with one. Isolation Valve - Haldex product category

Mike

Re: My HWH compressor problem

Reply #17 – December 09, 2017, 03:40:33 pm

Quote from: hdff – December 09, 2017, 10:28:45 am

Also I'm thinking about changing the Haldex dryer. It looks fairly easy to change using a factory Re manufactured unit. Just a few air hoses and the mount to the frame, am I seeing the whole picture. Where is the ID plate so I can get the model info off the old unit to get the new unit on site before I start.....

Howdy hdff, We both have '00 U320s, so I'm assuming the Air Dryers are the same. Here's a link to some p/n's. Part Number Collection
Also some pics of the unit MOT installed in our coach.
Good Luck, Dave A

Re: My HWH compressor problem

Reply #18 – December 09, 2017, 05:54:08 pm

one tiny check valve on compressor - it can be identified as it is stamped (tiny) into the brass with a marking that looks like a martini glass with a tennis ball in the glass, but with the glass (and tennis ball) laying down horizontaly

Tim Fiedler

Sure Start Soft Start

TCER Direct generator-gas-prod 630 240-9139
Gen-Pro

Re: My HWH compressor problem

Reply #19 – December 09, 2017, 08:54:46 pm

What/where is the protection valve jcuz speaks of and where is the Isolation valve located? Will Napa have these items also?

Keith

Re: My HWH compressor problem

Reply #20 – December 09, 2017, 09:18:09 pm

Quote from: hdff – December 09, 2017, 08:54:46 pm

What/where is the protection valve jcuz speaks of and where is the Isolation valve located? Will Napa have these items also?

Keith

Coach Air System Information and Guides [ForeForums Foretravel Motorcoach Wiki]
Go down to rear air tank picture. Valve right on tank. Little different location on every coach.
If you order from MOT or FOT you will pay a little more, but you will get the right parts.

Re: My HWH compressor problem

Reply #21 – December 09, 2017, 09:34:42 pm

Quote from: hdff – December 09, 2017, 08:54:46 pm

where is the Isolation valve located?
Will Napa have these items also?

Keith,

1. It is located on the air dryer where the air line from the compressor ties into the dryer.
2. They can order a new isolation valve but they won't have a rebuild kit in there system. They can order the dryer as they most likely won't have one on the shelf.
Mike

Re: My HWH compressor problem

Reply #22 – December 09, 2017, 10:11:39 pm

Quote from: hdff – December 09, 2017, 08:54:46 pm

1...where is the protection valve...

2...where is the Isolation valve located?

1. Go to the air system schematic linked in Reply #12. There is a protection valve on the "front" tank and on the "rear" tank. They are identified as valve "H". They are screwed directly into the tank, and other valves/fittings are most likely screwed into them.

2. The Haldex Pure Air Plus dryer may not have a separate external isolation valve. That function may be built into the dryer. In the description on the product page linked above (Reply #16), it says: "Built-in Turbo-Saver™ Valve reduces engine horsepower loss for improved fuel mileage."

If you do have a external isolation valve, it will look similar to the photos below, which show my AD-9 with isolation valve attached.

Re: My HWH compressor problem

Reply #23 – December 09, 2017, 10:41:39 pm

Silver ones are check, gold and black ones on tanks are protection.

Re: My HWH compressor problem

Reply #24 – December 09, 2017, 11:19:31 pm

Jim,

Looking at your photo (above), I don't understand the way your check valves are positioned. It looks like the check valves are downstream of the protection valves. That doesn't make any sense (to me). As far as I know, the check valves should be on the inlet line going into the tanks. Or am I missing something on your setup?

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