can't breathe, need air

[Isuzusweet]

83 on 82 chassis 310 TD

Okay, it turns out the rear air ride does work when my mechanic replaced the air level valve and added air through the system with his air line but he didn't test the compressor. I found the compressor has no power with a simple circuit tester, however I can't locate the bloody fuse. The Airstream manual states the compressor is powered through the accessory fuse at the automotive fuse block. I found the main fuse block and there was an accessory lead coming off the block but it was not a fuse but a lead going to the aftermarket stereo.
If someone......Mike maybe......could tell me where the fuse is for the rear compressor on the fuse block I'd appreciate it as I detest electrical gremlins .
Thanks in advance
Tony

[Smartstream]

Tony here is a picture of my fuse block.



The 20 amp fuse in the upper right center is the air bag compressor. That fuse feeds the "F" take off. The problem is it is marginal to power the compressor. Many of us take a heavy lead directly from the battery, through a relay to the compressor. Then you can feed the relay from the ignition with a much smaller current draw and still power the compressor with the heavy current it needs.

Here is a picture of the wiring of the fuse block.



The added arrows show the fuse and connection to the accessory plug at "F".

Cheers, Dan

[Isuzusweet]

Thanks huge Smartstream

I like your idea of running a line from the battery through a relay and using the original fuse line as a control. If it hasn't been done I will do it that way.
It was just frustrating as I'm a person that starts at the beginning (make sure ignition is on), to then check fuse.... with no fuse diagram.....none in the Airstream manual and none on the glovebox door which had been replaced by a piece of wood by a PO.

Again huge thanks. I will go tomorrow and check.

[Mike Leary]

Have you checked for power at the 60-40 switch (which activates the compressor) in the rear roadside compartment? It could be the problem there, as they took (take) water on the road. Did the compressor work before the mechanic got to it? I have an in-line fuse at the compressor, and are you sure the bags need air? Remember the 10" rule of air bags.

[idroba]

I second the motion to relay the compressor, and use the original line only to control the relay coil with a new #10 running directly to the engine battery. I did that on both my '83 310 and my GMC with air suspension, and it helped a great deal in minimizing compressor run time and heating up.

[bkahler]

Tony,

Here are the owners and factory service manuals for the 84-86 310/325/345 motorhomes. Hopefully they will help you in your trouble shooting efforts.

310 service manual

310 owners manual

I second Dan's comment about adding a relay in line with the compressor. That was the very first modification I made to our 310. The fuse block was melted where the compressor fuse was located. Well worth doing.

Good luck!

Brad

[Mike Leary]

All this talk about relays and adding #10 wire has me confused: are all your coaches on the original compressor? I'm sure not and have not had fuse blowing or running-on at all.

[bkahler]

Originally Posted by Mike Leary

All this talk about relays and adding #10 wire has me confused: are all your coaches on the original compressor? I'm sure not and have not had fuse blowing or running-on at all.

The compressors draw a lot of current and the way Airstream wired them was to run a 12 or 10 gauge (not sure which) wire from the fuse block all the way to the back of the coach to the compressor. DC voltage drops quite a bit on long runs especially if the wire is undersized for the load. The lower the voltage the higher the current draw. If or when the compressor finally seizes or as it gets older and has to run longer due to lower output then the wire and connection at the fuse block starts getting hot. I'm not kidding when I say my fuse block was so melted at that fuse location that I had to install an auxiliary block just to power a relay. The relay is located in the same compartment as the air compressor and I pulled power from the generator compartment via an 8 gauge wire. The pump runs great now.

[Mike Leary]

After sitting for a couple of weeks or so, my compressor will come on for a few minutes (usually the time I take to warm-up the diesel). I assume it is making-up and normal, because I've measured the bag height before and after, and it's only a inch or so difference. I had big problems before the compressor and relay were replaced.

[Smartstream]

After starting the engine and the initial fill of the storage tank and air bags the compressor should run very little. The leveling valve has a delay built in so going down the road normally will require no air. A change of load such as taking on 50+ gallons of fuel or water or dumping the holding tanks will cause a valve/air bag adjustment. Another thing is hydraulic leveling jacks, raise the rear and the valve will dump air to try to lower the ride height.

Airstream probably figured with the limited compressor run time they could get away with minimum wire size. As the system ages and inefficiency sets in we have to come up with a way to help the system. Also I replaced my compressor with a larger unit as I'm sure many others have done the same. This makes upgrading the wiring a prudent thing to do.

By the way to answer Mike, I did swap out the original compressor about 3 years ago, it was a belt driven unit made by Perfect Circle I think.

Cheers, Dan

[Isuzusweet]

Just out of curiousity....How big was the original compressor? Mine has obviously been replaced as the new one is very shiny, deems very small and is not tethered down. What was rhe original CFM or SCFM I wonder.

Mike....I tested the compressor switch with the circuit tester with no power at any of the terminals thats when I headed to the fuse block. I'm taking in a spare battery to short the pump to make sure it's working.

Thanks bkahler for the manual link.

I'll keep you posted.

[Smartstream]

I have never found any info on the original compressor. I believe somebody on this forum indicated they were Perfect Circle. Mine was a little belt driven V-twin and it weighed about 1/3 of what the replacement weighs. I don't know if this is because of capacity or light weight materials. This is my replacement compressor. It's probably overkill buy I like it.

VIAIR Corporation - 450C IG Part No. 45050 45058

Cheers, Dan

[Isuzusweet]

Thanks for the info on the compressor Smartstream. However your compressor is drawing 19 amps at 12V. If I buy that one wiring direct from the batteries with a relay to the fuse block and a fuse upgrade will be a must.

I found the 20 amp fuse dead behind what seems to me a lot added wire from a PO. It was burnt and very faded. I replaced it and turned the ignition to acc, hoping for the buzzing of the compressor........what I got was a very healthy SNAP from the fuse block.
Plan B....Got my spare battery and hooked up the positive to the compressor and then touched a lead from the neg on the battery to the ground contact. The arcing was impressive with the wires starting to melt right away. The compressor didn't even budge. I then kept the compressor unhooked, replaced the fuse again, prayed and turned the key to acc. The fuse held so I don't have a short, just a crapped out compressor.

Please continue to send info on replacement compressors.

Thanks to all

[bkahler]

I believe the original V twin cylinder compressors were made by Dana. Five or six years ago I found a source for getting them repaired. I think it was something like $75 at the time. If you're interested I can dig up the contact information.

These same compressors were used on other brand motorhomes of the era and they do seem to last a long time. I believe ours is still the original compressor. The biggest problem is the undersized wire that airstream used from the fuse block to the compressor.

Brad

[Smartstream]

Originally Posted by Isuzusweet

Thanks for the info on the compressor Smartstream. However your compressor is drawing 19 amps at 12V. If I buy that one wiring direct from the batteries with a relay to the fuse block and a fuse upgrade will be a must.

I found the 20 amp fuse dead behind what seems to me a lot added wire from a PO. It was burnt and very faded. I replaced it and turned the ignition to acc, hoping for the buzzing of the compressor........what I got was a very healthy SNAP from the fuse block.
Plan B....Got my spare battery and hooked up the positive to the compressor and then touched a lead from the neg on the battery to the ground contact. The arcing was impressive with the wires starting to melt right away. The compressor didn't even budge. I then kept the compressor unhooked, replaced the fuse again, prayed and turned the key to acc. The fuse held so I don't have a short, just a crapped out compressor.

Please continue to send info on replacement compressors.

Thanks to all

I have to assume that even though you don't say that with your compressor disconnected you have 12 Volts at the disconnected wire. If that is the case you are in good shape. I don't know the amp rating of the factory compressor however running on a 20 amp fuse it must have been significant. As others have stated there is evidence of over heating and burning at the fuse block. With this in mind running from the battery through a relay using the original circuit to operate the relay would solve the problem.


As stated before I lean toward over kill so keep that in mind as you follow along. I have replaced many of the relays used on headlights and A/C systems that were burned just like the fuse block. So I used a continuous duty starter relay like you will find behind your batteries to connect the house to the chassis battery for starting. They are easy to find and cost about $25, just make sure you get one rated as continuous duty.


For the compressor as I have said before, if your system is in good shape, the compressor after filling the tank and air bags at start up should not need to run very often if at all. That does not mean that I want a minimal compressor. I like the 100% duty cycle at 100 PSI. If I choose to use the system to inflate the tires for example it will handle it. I believe the system is pretty much bullet proof so the few extra dollars are well spent.

Good luck, Dan

[Mike Leary]

Gets pretty confusing back there, especially with all the different opinions, does it not? Have you checked the pressure at the accumulator tank? Are the bags deflated? The compressor I have is a Gast, # ROA-P181JH. The replacement bush is # AJ896. I have a 25 amp in-line fuse back there, and it looks like 8/10 gauge wire. Air bag problems are not uncommon, I've seen 345s with outside air outlets for each bag so they could air without crawling underneath. Those compressors are not cheap, I think I paid $800.00 for mine, but it's lasted and lasted.

[Isuzusweet]

Originally Posted by Smartstream

I have to assume that even though you don't say that with your compressor disconnected you have 12 Volts at the disconnected wire. If that is the case you are in good shape. I don't know the amp rating of the factory compressor however running on a 20 amp fuse it must have been significant. As others have stated there is evidence of over heating and burning at the fuse block. With this in mind running from the battery through a relay using the original circuit to operate the relay would solve the problem.


As stated before I lean toward over kill so keep that in mind as you follow along. I have replaced many of the relays used on headlights and A/C systems that were burned just like the fuse block. So I used a continuous duty starter relay like you will find behind your batteries to connect the house to the chassis battery for starting. They are easy to find and cost about $25, just make sure you get one rated as continuous duty.


For the compressor as I have said before, if your system is in good shape, the compressor after filling the tank and air bags at start up should not need to run very often if at all. That does not mean that I want a minimal compressor. I like the 100% duty cycle at 100 PSI. If I choose to use the system to inflate the tires for example it will handle it. I believe the system is pretty much bullet proof so the few extra dollars are well spent.

Good luck, Dan

I forgot my circuit tester at home when I went to check this morning so I will double check tomorrow before work that I have 12V to the disconnected wire coming from the compressor spring switch. (here's hoping but I don't see why not).

As for the relay, thanks for the info but since I'm a cabinetmaker and not a rocket scientist, I'm having a bit of a head scratch on how to wire it in.
I have the hot 20A wire coming from the fuse block to the compressor activation switch in the aft compartment, right. When the switch detects air below a certain threshold it trips and starts to draw power from that hot wire. SO, to divert power draw from the fuse block to the batteries themselves I interupt that line in the aft compartment, just before the switch with a relay, with another line travelling to an inline fuse and then the batteries. SO when the switch trips, it starts to suck power from the line leading to the fuse block, tripping the relay, allowing for power to be drawn from the batteries directly through another fuse. Correct????

See link below and please suggest a possible relay. Thanks

http://www.texasindustrialelectric.com/relays.asp

Please excuse my ignorance, but electricity, computers, wives and daughters are completely foreign alien beasts to me; although I have done all the electrical in my house and it hasn't burn't down yet, so there is hope.

[Isuzusweet]

Originally Posted by Mike Leary

Gets pretty confusing back there, especially with all the different opinions, does it not? Have you checked the pressure at the accumulator tank? Are the bags deflated? The compressor I have is a Gast, # ROA-P181JH. The replacement bush is # AJ896. I have a 25 amp in-line fuse back there, and it looks like 8/10 gauge wire. Air bag problems are not uncommon, I've seen 345s with outside air outlets for each bag so they could air without crawling underneath. Those compressors are not cheap, I think I paid $800.00 for mine, but it's lasted and lasted.

Hi Mike, glad you're still around.

I did open the tank drain and it was empty and yes the bags are at their lowest level, (it was a bumpy ride back from Ohio). I want to get this system working correctly, as someone stated with the levelling valve, it constantly dumps and adds air depending on gasing up or running empty.

Thanks for the compressor info. My current one is just a single stage air bag compressor like the Viair one Smartstream has, (probably not as robust though) but definately not a V-twin compressor.

Thanks again.

[Mike Leary]

Unless "others" have worked on the coach, spring shop that works on Fire Dept. chassis or a Peterbuilt shop would (and has been) my choice. While you're at it, have them align the coach and check those crappy front coil springs.I don't know, also, if your "mechanic" even knew how to adjust the leveling valve.

[Isuzusweet]

Hi Mike

My shop is a heavy equipement shop dealing in IH products, so they know about air systems, just a little lazy at not checking the compressor first IMHO. My bad for not checking it first before taking it in.
The front end was completely rebuilt in Aug of this year by the PO. New ball joints, springs, air bags and one new bell crank idler. All parts are Supersteer and so is the new bell crank I have coming from Oregan for the other side that wasn't changed. Hopefully they performed the motorhome alignment when they did the work. It does track straight and true with minimal play in the steering.
Thanks for the Gast compressor. I did punch in the number but it wasn't recognised by the Gast website so I have e-mailed their tech dept to see if numbers have changed and hopefully they will send me some info on a suitable compressor.

Thanks again
Tony