All 3 roof airs failed simultaneously?

[plyonsMC9]

Greetings fellow busnuts!

Well, finally some time up north with good weather and no salt on the roads.  So, out came our bus.  Throttle/cable stuck a little.  Took care of that. 

Only real problem? Bus was fine - but ALL 3 of my roof air conditioners do not function. 

Symptom is the same on all 3.  The fan will not start on any of them.  I did not use the a/c's during the winter.  Compressors run, I guess.  Just a humming sound.  When I turn just the fan on, I hear a quieter hum.  Each a/c is on a separate breaker.  At first I thought it may be a problem with the generator, but I plugged the coach into a shore 50 amp circuit.  Same symptoms. 

My panel voltage meeters show 122 volts.  All lights, refrigerator, portable heaters, etc., function w/o any problem.  Two of the a/c breakers are on one leg, the other a/c breaker is on the other leg.

a/c breakers also trip / spark now.

Where do I start on something like this?  Help! 

Thanks! Phil

[luvrbus]

 Phil take the covers off the top on the roof and free the fans on top happen to me before on a S&S  good luck

[coachconverter]

Sounds like the fan motors have locked up.  I would try to spin them manually, then lube them up. 

[JohnEd]

Had this happen with one once.  The squirrel cage was "stuck".  Take down the inside shroud/defuser/filter.  Look up in there and see the sq. fan rotor.  Make sure it spins freely.  DON"T leave it in the "ON" posit for long or you will burn up the motor.  LOW AC will do this so check you ac volts when you try the AC.  Do they act the same in generator mode?

You will get this one soon.  The really bad ones are easy.  Now if you had a sit where only one would work on odd numbered Tuesdays.....then that would be significant.

John

[plyonsMC9]

Thanks guys!  I will (carefully) get up on the roof, remove covers, spin the fans.  Is it easy to lube the motors?  I will post back with my progress during the week.  Breakers are OFF to all three units right now. 

Kind Regards, Phil

[Sean]

Phil,

It's possible, as luvrbus and others wrote, that the motor shafts are bound up, and spinning them by hand will free them.  (If that does turn out to be the problem, you can avoid it in the future by running all your units for a few minutes each month, even in the winter.  About five minutes should be sufficient to circulate the refrigerant and its entrained lubricating oil.)

That said, I find it strange that this would happen to all units simultaneously.

I would pop the ADB or duct cover off each unit and test the power right at the unit with a voltmeter.  It's possible you have some common failure, such as a neutral bus issue.

Another thing you can try is to get a heavy-duty extension cord of suitable length, whack the receptacle off the end, and wire it directly to one of the units (disconnecting the unit from its hard-wire source, of course), then plug that into a known good shore-side receptacle, and see what happens.

Let me know where that gets you and we can take it from there.

-Sean
http://ourodyssey.blogspot.com

[plyonsMC9]

Hi Sean,

Cover is already off one of the units.  This will be e-z for me to test.  Also have a cord with the end wacked off coincidentally.  Nothing at all to do with my electric shrub trimmer getting out of control with my outdoor extension cord of course.      Yes, unusual that it would happen to all 3.  Normally I keep the a/c covers on all winter, but this year, I got iced before I could get them on, and I don't dare go on the roof w/ ice up there, so I decided to forego the a/c covers this year.

Kind Regards, Phil

[Nick Badame Refrig/ACC]

Hi Phil,

The guy's covered everything that I would have started you from. Thanks Guy's!

The only other thing I can add is if this turns out to be your problem, get some oil on the shaft ends up close the the bearings.

Even though you have sealed bearings, it will still seep somewhat into the seals.

Good Luck
Nick-

[jeffacc]

Hi Phil
  If the fans are not bound up check the capacitors you will need a meter that is cabable of reading microfarad as for starting the units in winter don't do it you will take the valves out in the compressors check with your manual for operating temps good luck.
                                                            Jeff

[jok]

Hi Phil,

I'm in S.W. Michigan and am enjoying the great weather you guys are sending us. Keep it coming.

I have three Dometic Duo-Therms that had a similar failure. When I installed mine I wired all three to a Duo-Therm Comfort Control Center. The three are controlled by normal household phone lines, and they are tied together. I had to use a "in-line coupler" to tie them together. The "coupler" was low quality. When I had the failure I followed the "phone lines" and when I wiggled the front "coupler" all three came to life. I replaced the coupler and they have worked fine.

I also have blown the fuse that is under the cover (on the roof). I am glad I installed a sunroof to get on the roof.

Good luck,
John

[belfert]

I think Phil is confusing A/C covers sometimes used in the winter for the plastic shrouds.  To get to the fan motors will require removing either the inside covers or the outside plastic shroud.

I also highly doubt all three fans locked up at once.

[FloridaCliff]

Phil,

Don't know what kind of units you have, but my Coleman units require a 12 vdc control voltage to work.

If you have the same or similar, maybe a a fuse blew or wire disconnected over the Winter.

Cliff

[Dreamscape]

Phil, What did you come up with?

Did you check voltage at each unit as it goes in?

Critters maybe chewed some wires?

Let us know.

Paul

[plyonsMC9]

Thanks Paul,

Tonight when I get home from work I will take some readings, check voltage, and post results!!  I'm very curious about this.  I really appreciate all the feedback & excellent suggestions.  Initially when something like this happens, it can be intimidating, but - NOT with the best busnuts in the world helping ya out!    

Kind Regards, Phil

[plyonsMC9]

Phil,

Don't know what kind of units you have, but my Coleman units require a 12 vdc control voltage to work.

If you have the same or similar, maybe a a fuse blew or wire disconnected over the Winter.

Cliff

Hi Cliff, pretty sure they are Dometic low profile.  I'll check tonight for any kind of 12 vdc wires.

Thanks! Phil