12 volt air compressor fuse size

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12 volt air compressor fuse size

April 02, 2021, 08:34:46 pm

The tech removed the fuse to my 12 volt hwh air compressor. I can't find it and can't find it in the schematics.

How many Amps?

Re: 12 volt air compressor fuse size

Reply #1 – April 02, 2021, 08:36:41 pm

One of them is a 5 amp fuse probably that would be the one.

Re: 12 volt air compressor fuse size

Reply #2 – April 02, 2021, 08:48:47 pm

Control wiring is 5 amp fuse. The 1/3 HP compressor is 28 amps. The circuit breaker should be about 35 amps.

Re: 12 volt air compressor fuse size

Reply #3 – April 02, 2021, 10:46:28 pm

I tried a fuse, but the compressor runs continuously. Now I know why the fuse was removed.

Re: 12 volt air compressor fuse size

Reply #4 – April 02, 2021, 11:22:31 pm

As best I can figure there are three ways for the compressor to come on.
1. Make sure the dash switch is off, that opens the air line solenoid to the wet tank, lowers pressure and starts the compressor
2. If the pressure switch is below the start point then it sends a 12v signal to the essex relay to start the compressor.
3. If the HWH system sends a 12v control signal to the essex relay the compressor will start.

Any of these will start the compressor and actuate the 12v NO solenoid on the water trap. If it is hot then one of them is calling for air.

Removing the fuse disables the switch and solenoid to the wet tank and power to the pressure switch.

If it still comes on them test for 12v at the trigger side of the essex relay. If it has 12v then the HWH system is calling for air.

If the fuse is in and it is not the HWH system then the pressure switch is closed, the essex relay trigger has +12v and the compressor runs. The switch could be bad, the compressor may not be compressing or you have a significant leak. If it is not leveling the coach the compressor is filling the HWH tank which provides pressure to the seal manifolds. The tank pressurizes to about 90 psi. The slide seals are regulated to about 12 psi.

To completely disable the compressor and not let the water trap solenoid stay hot, move and merge the HWH control wire and diode (you might have to add a new diode) to the wire from the pressure switch and add an on/off switch between that junction and the trigger side of the essex relay. Doing so means nothing can energize the essex relay and therefore the compressor and since 12v does not get to the essex relay trigger the water trap solenoid is not energized.

Re: 12 volt air compressor fuse size

Reply #5 – April 03, 2021, 08:14:27 am

Quote from: Roger & Susan in Home2 – April 02, 2021, 11:22:31 pm

If the fuse is in and it is not the HWH system then the pressure switch is closed, the essex relay trigger has +12v and the compressor runs. The switch could be bad, the compressor may not be compressing or you have a significant leak.

^ Pulling this out to emphasize it ^

If you cannot get the aux compressor to stop running unless you pull the inline fuse, you have an issue that needs attention.

The primary causes we have seen are a leak in the slide bladder system and a leak at the bottom of the clear condensate bowl that has the NO solenoid on it (or debris on the seat of the NO solenoid plunger), hindering or preventing build-up of pressure.

Re: 12 volt air compressor fuse size

Reply #6 – April 03, 2021, 01:27:00 pm

It is fairly easy to add a 90° turn valve to the bladders to isolate them and a pressure gauge to monitor pressure in them. And add a pressure gauge to the HWH tank too. When the compressor is off and the water trap solenoid is open there is no pressure from the check valve by the pressure switch back to the compressor. All of this assumes your system is original, not modified and functioning. Later models (past 2001) had some factory installed valves.

If you lose the compressor or have no pressure in the HWH tank you cannot deflate the slide bladders. You can add a small vacuum pump plumbed in properly as a backup to deflate the bladders to allow you to get them in. It does nothing to reinflate them.

Re: 12 volt air compressor fuse size

Reply #7 – April 03, 2021, 02:00:15 pm

Tom,
Is it the original Thomas Brand compressor? I had the same issue with the compressor never shutting down. I was confident that I didn't have leakage anywhere so that it never turned off.
I removed the compressor and took the head apart. Sure enough, the plastic seal inside the cylinder was shot. One edge had a tear in it. Even though it sounded normal when running, it was not compressing any air.
They do have a rebuild kit available for a couple of hundred dollars. I just ended up replacing the compressor. No promises, but it may be worth a look.

Re: 12 volt air compressor fuse size

Reply #8 – April 03, 2021, 02:19:09 pm

After I run the compressor for a few seconds and then pull the fuse, I can hear the hiss of air escaping for a second. Sounds like it's coming from the overpressure release valve. I'll been to cut some cable ties to get to it after I get home from this short trip.

Re: 12 volt air compressor fuse size

Reply #9 – April 03, 2021, 03:21:06 pm

Tom it might be the unloader valve bleeding off air which is normal.

Re: 12 volt air compressor fuse size

Reply #10 – April 03, 2021, 03:38:01 pm

Quote from: oldguy – April 03, 2021, 03:21:06 pm

Tom it might be the unloader valve bleeding off air which is normal.

It never stops

Re: 12 volt air compressor fuse size

Reply #11 – April 03, 2021, 04:55:50 pm

Oh! That is a problem.

Re: 12 volt air compressor fuse size

Reply #12 – April 03, 2021, 05:13:17 pm

Mark, the compressor in your coach is the smaller 1/10 hp compressor. In 2002 and later they wend to a significantly bigger 1/3 hp Thomas compressor. Rebuild kist are available for both. I bought a new smaller one for my coach, rebuilt the original one, sold both and bought the bigger Thomas compressor for much more $$.

This one is about 1/2 the price of the bigger Thomas compressor, has a high duty cycle rating, up to 150 psi. Other have used these. It might be worth a try. This source has $50 off and free shipping.
ARB 12V Twin Compressor | CKMTA12|Northridge4x4

Re: 12 volt air compressor fuse size

Reply #13 – April 06, 2021, 03:26:39 pm

I'm home now, and after cutting some zip ties and spraying the water trap assembly with 409, a mound of bubbles has shown me where the air leak is. Looks to be one of the threaded fittings at the bottom of the clear water trap, leading to the selenoid.

It's a tight fit for my fat fingers. Does the clear bowl come off for easier access? Is one of the fittings screwed directly into the clear bowl?

Re: 12 volt air compressor fuse size

Reply #14 – April 06, 2021, 03:30:29 pm

Quote from: Tom Lang – April 06, 2021, 03:26:39 pm

I'm home now, and after cutting some zip ties and spraying the water trap assembly with 409, a mound of bubbles has shown me where the air leak is. Looks to be one of the threaded fittings at the bottom of the clear water trap, leading to the selenoid.

It's a tight fit for my fat fingers. Does the clear bowl come off for easier access? Is one of the fittings screwed directly into the clear bowl?

If it's like mine yes. There is a aluminum fitting in the bottom of the blasting bowl. Subject to corrosion. Hex head inside. The plastic bowls are prone to crack
Scott

Re: 12 volt air compressor fuse size

Reply #15 – April 06, 2021, 04:25:36 pm

Quote from: Tom Lang – April 06, 2021, 03:26:39 pm

I'm home now, and after cutting some zip ties and spraying the water trap assembly with 409, a mound of bubbles has shown me where the air leak is. Looks to be one of the threaded fittings at the bottom of the clear water trap, leading to the selenoid.

It's a tight fit for my fat fingers. Does the clear bowl come off for easier access? Is one of the fittings screwed directly into the clear bowl?

It does come off easily, but if you're talking about the condensate bowl, the problem is likely the plastic bowl itself having developed thermal cracks or corrosion of the fittings.

Tutorial with part numbers:

HWH Filters and Bowls

Re: 12 volt air compressor fuse size

Reply #16 – April 06, 2021, 10:46:54 pm

This one may be an alternative to the OEM water trap and solenoid. I used this one in my rebuild. It is a filter and moisture trap, the bottom valve closes under pressure and opens when pressure is reduced and lets the water out. You can attach a drain tube. It needs to go in ahead of the check valve before the pressure switch.

PneumaticPlus SAF3000M-N03BD Compressed Air Particulate Filter 3/8" NPT -...

Re: 12 volt air compressor fuse size

Reply #17 – April 07, 2021, 04:43:57 pm

Roger, I would like to copy your setup. Do you have part numbers for the pressure switch by chance ?

Thank you

Re: 12 volt air compressor fuse size

Reply #18 – April 07, 2021, 05:00:46 pm

Not Roger, but looks like a regular Square D pressure switch, pretty sure any big box store will have them

Re: 12 volt air compressor fuse size

Reply #19 – April 07, 2021, 07:17:49 pm

This is the pressure switch I used. I adjusted the upper cutoff pressure from about 90 psi to 95 psi.

I added pressure gauges to the HWH tank, the air bladder and assembly ahead of the pressure switch.

This is the second air filter, 5 micron.
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Check Valve
Control Devices-M2525-1WA Brass Ball Check Valve, 1/4" NPT Male: Industrial...

Re: 12 volt air compressor fuse size

Reply #20 – June 19, 2021, 06:51:00 pm

I have presented this issue on other talks on this forum, but I am going to revisit this on this post to see what answers I get.
I never hear my air compressor (located in the front large bay drivers side, beside the Inverter) come on.
I level my coach, with the 4 red lights on, then I just turn the key off. The red light REMAINS ON bright all the time. Over a couple of days the coach begins to lower (the red light remains on still.....no sleep mode, blink dimly..anything) and the air compressor does not turn on. After a couple of frustrating days of watching this happen, (and yes I may have a leak somewhere..) I start the coach until the air brakes pop off at about 120, then re level. The coach airs up and the saga continues.

Is there a fuse (and where the heck is it located???) for the air compressor that may be blown?
Am I truly missing something here?
I do remember the air compressor coming on and viewed it last summer..
Help!
Peter

Re: 12 volt air compressor fuse size

Reply #21 – June 19, 2021, 07:00:28 pm

Quote from: dicksop – June 19, 2021, 06:51:00 pm

Is there a fuse (and where the heck is it located???) for the air compressor that may be blown?

Peter,

Your HWH compressor is on a manual reset breaker in the basement. It is hid behind the removable fiberglass panel that is hanging on the basement wall big bay drivers side.. You will find there is a little button that will be popped out, take a pencil and push it back in.

Mike

Re: 12 volt air compressor fuse size

Reply #22 – June 19, 2021, 07:18:53 pm

Hi Mike,
attached are pics of behind the white fiberglass panel drivers side first bay. I do not see any reset breakers for the compressor.
Am I looking in the wrong area?
Peter

Re: 12 volt air compressor fuse size

Reply #23 – June 19, 2021, 07:33:43 pm

Should look like this

Re: 12 volt air compressor fuse size

Reply #24 – June 19, 2021, 07:37:13 pm

well if this it, it is not labeled...

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