BENDIX AIR DRYER AD-4

[bevans6]

It's factory on mine but definitely a factory option, and the connection is shown in the schematic and mentioned in the manual, so I thought it might be common to John's MC-9, since they are both from the same date.  According to the manual, they were optional, though.  The heater is a "60 watt 24 volt heater thermostatically controlled to 50 deg to 85 deg".

I thought it worth mentioning because some people may have removed the bus heat blower motor and not realized that the same switch that turns on the heat/AC evaporator blower turns on the air dryer purge valve heater.  Strictly speaking, the dash switch is a dual gang switch, up turns on the AC and runs the blower on high, down turns on the blower and sets it to low speed.  The switch terminal that runs to the blower motor low speed terminal is the one that turns on the purge valve heater.  It also would turn on the optional Expello valve heater, which is an automatic drain for the wet tank.

Brian

[buswarrior]

Pay attention to Brian's good explanation, MCI busnuts!

Ripping out the stock HVAC and not finding a source of power for the air drier will leave you parked somewhere in the cold with no air pressure!

Running the coach in the cold with the HVAC switch turned off will also cause air problems.

Where, north of the Mexican border, did we not see freezing temps in the last few weeks?

Leave your air drier purge valve un-powered at your peril!!!

happy coaching!
buswarrior

[gus]

John,

You back in TX yet?

[Nellie Wilson]

Belfert-

Heck of a good price... beats the $680 price quoted me in White River Junction. Of course, WRJ carries top quality stuff, like $1000 compressor governors. Mine lasted nearly one full year

Nellie

[Ed Hackenbruch]

Bus Warrior, no freezing temps in Yuma

[belfert]

Nellie, for $680 I sure hope they were at least going to install it for you.  I don't recall ever seeing an AD-9 even at Napa for more than about $250 or so.

Someone must be looking for a buyer that wants to make the owner's boat payment for the month.

[NewbeeMC9]

Mine came with dryer but not heater,  guess because the Original owner was trailways in 'Bama and it ran folks to Orlando from what I here.

After having frozen air dryer issues, here was my saga trying to hook up the heater,  I thought it was just the fuse and come to find out there was no wire at all.

http://www.busconversions.com/bbs/index.php?topic=10721.0

Mine had been replaced and the heater was 12v,  there is a link to the 24v heater part # in that thread


Johns4104s, did you look to see if you had one?

 you can service it if you run the front up on blocks and you may be plumbed for it if you don't have one

[Nellie Wilson]

Belfert -

Where were you when I needed you?

I didn't know the air dryer heater was controlled from the coach. My 'mechanic' said it was 'automatic' and probably just burned out. But now I see it works just fine!

Oh, the cost of ignorance. When I think of the AGGRAVATION (and expense) a little knowledge could have saved me...

And the worst part? I know I'll go through it again and again, until I learn one heck of a lot more.

I swear I'd drop everything if i could get a real old-fashion 'bus guy' to take me through 'bus immersion school.' I've learned one thing though: When someone says, "Oh, it's just like a truck," I know they don't know squat.

Thank you - and you too, BW - for the knowledge.

Nellie Wilson

[bevans6]

Nellie, you could do what I did - get the manual, get the bus, read the manual cover to cover (a few times, I have about worn out sections of my manual in the 8 months since I got it and the bus) and go out and look at the bus to find the bits in the picture.  Take the air brake course.  You already do all the maintenance yourself and none of this is rocket science!  After a while it all starts to make sense, particularly with the help and feedback from the board members who have the life long experience we are trying to emulate!

BTW, on your air lines.  I have been going through and replacing all of the original air lines (a lot of mine were still original!) with fabric covered heavy duty air line from my local hydraulic shop.  I've been making up oil and hydraulic brake lines for my race cars for years, so when I went in to get an air line made up, they sold me the line in bulk and a bunch of the  end fittings.  The hose cuts to length easily with hose cutters or a hacksaw, and with a vise and a couple of wrenches you can assemble the ends onto the hose really very easily.  Maybe ask about that at the air line store, and you could buy a bunch of hose and some ends and make up what you need yourself.  Saves the assembly fee, which at my place is a flat fee that is often more than the cost the parts, so your price more than doubles.  For brake lines, modern practice has the nylon line that looks like PEX and push on fittings.  They assemble with no tools at all, and are designed to be really easily repaired at road side.  Something that I am going to investigate fully when I start going through my brake lines and cans in the spring!

Brian

[Tom Y]

NewbeeMC9, What model drier to you have? I have a 24v heater, I think but will have to look. It may be a AD 2   Tom Y

[busshawg]

My opinion regarding the original question , fo rwhat ever it's worth. Go with a AD-9, everyone uses them, they work great, most shops will have parts or a replacement. If you go to a truck wrecker/shop you may even find one that isn't very old and be able to get the mounting brackets as well for a very reasonable price. Worked for me.

Grant

[NewbeeMC9]

NewbeeMC9, What model drier to you have? I have a 24v heater, I think but will have to look. It may be a AD 2   Tom Y

Thanks TomY, I have an AD-9 and it came with a 12V heater.  I found out the hard way that i didn't have the wire in the first place.

It is all hooked up now.  I have 100 amp equalizer so plenty 12v.

Funny thing too is if you bypass the switch, you kill one battery if it gets cold ,  I have it going through switch now too.

[Nellie Wilson]

Bevans6 -

That is welcome information. I thought attaching end fittings would be bear... special tools and all that. in fact, that's the main reason I haven't begun to replace lines. Just seemed so tedious. you know, pull the line and take it to the shop, then wait to get a new one made up, then... well, you get my drift.

But doing it your way, I could do a little at a time. And, eventually, they'd all be fresh!

BTW, I used that nylon / push on system when installing plates and replacing some air bags. They are sooo slick, even I could do it. Main thing is to cut with something really sharp, so you don't crease the nylon.

I'd like to use them everywhere, but don't if they'd work (be safe) for certain applications?

Nellie Wilson

[buswarrior]

Regarding the push on fittings,

I'd be concerned as to their useful life, and when will they start leaking or pull apart due to age.

The designed useful life of a new truck or bus isn't what it used to be.

anyone have connections?

happy coaching!
buswarrior

[bevans6]

The hoses I have been replacing so far were in the engine compartment, so potential for excess heat and so I used the heavy fabric covered hose.  Push-on hose seems to be used  extensively in industry for brake and suspension lines outside of the engine compartment, or where heat isn't an issue (lines to/from the compressor itself come to mind).  But that's just my observation looking at trucks and from my air brake course (instructor was a long time truck mechanic/driver/small fleet owner and liked the nylon a lot).  Lord knows the fabric lines I replaced had a best-before date long expired, so they don't have indefinite life.  I will be really curious to learn what others closer to the industry think of the push-on hose system, life time, applications best suited, and all of that.  My MCI made  in 1980 has the nylon line in use for the air door, and wipers, so it seems to have lasted a long time in that application, although I don't think those lines have pushon fittings.

Brian