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
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
Sounds like the fan motors have locked up. I would try to spin them manually, then lube them up.
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. :o 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. 8) Now if you had a sit where only one would work on odd numbered Tuesdays.....then that would be significant. ;D
John
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
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
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. :D 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
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-
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
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
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.
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
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
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! ;D ;D
Kind Regards, Phil
Quote from: FloridaCliff on April 20, 2008, 08:29:09 PM
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
Phil,
Look at the good side, at least this did not happen in July or August when the temps are much hotter. Based on my limited experience with roof airs, I would be inclined to think it is a low voltage issue since all 3 failed at the same time. Good luck and let us know what you find. Jack
Three units at one time, I guess its possible, but I'd check my neutral coming in to the bus, I've been wrong before but its easier checking one thing first than 3! Good luck!
Hi jeffacc,
I don,t know about your roof A/Cs, but mine have heat or fan only positions on the control so the compressor would never come on if you want to run the blower once a month in the winter. Even if you turned the control to A/C, I doubt that you could turn the thermostat low enough to get the compressor to start.
Some of you are suggesting electrical problems, but you are overlooking Phil's statement that the motors are pulling high amps, indicating a locked shaft.
Phil, good luck with the problem.
Sam 4106
Thank you for the response Sam - I did have to make a correction to my original post, what I meant to say ( phil is embarrassed at this point) was the voltmeter was showing 122 Volts, not amps. Very sorry about the snafu.
Thanks again - more to come in hopefully just a couple of hours when I reach home.
Best Regards, Phil
--------------------------------------------------------------------------------
>>>Three units at one time, I guess its possible, but I'd check my neutral coming in to the bus, I've been wrong before but its easier checking one thing first than 3! Good luck!
>>>It's possible you have some common failure, such as a neutral bus issue.
**************
Sounds suspiciously like a bad nuetral to me too,and that would explain all 3 at one time - Check your bus bar?
Hi folks, Thanks for all the responses! It is very much appreciated. ;D
I just returned from the bus as Nick was reporting BBS problems - and I was actually working on my bus. :D
Well, first thing I checked - squirrel cages. First the center a/c. That squirrel cage was STUCK! Got it moving pretty good. turned on the fan. She worked! Ha Ha - Phil thinks he is home free!!
Checked the rear a/c squirrel cage. STUCK. Ha Ha. Get the cage moving. turn on the power, turn on the fan ------------ just a very quiet low hum. a/c condenser, louder hum. OK, turn it back off. Check front a/c. Squirrel cage - STUCK. unstick. turn on fan. just a very quiet hum. >:( Grrrr.
1 out of 3 are working. Of course that is the one that I don't use since it has a tendancy to leak water inside after a while of operation. But, it is working. :D
Try Nick's idea. oil on the shaft near the blower motor. get the cage moving even better. downstaris. try both front & rear a/cs, Nothing, except the veeeerrry quiet low hum.
Next, check voltage at the front a/c instead of back by the panel. My voltmeter says 121 volts. almost exactly what it says at the panel. At that point, I'm being paged to fix the bbs, my kids are running out of control, and I am back in the house.
What would be the next logical step? Any kind of fuse which could have blown on the blowers?
Thanks again all!!!
Best Regards, Phil
Phil, I had trouble with one of my ac's and it turned out to be the capacitor. It was fried!
BS
Quote from: Blacksheep on April 21, 2008, 06:58:30 PM
Phil, I had trouble with one of my ac's and it turned out to be the capacitor. It was fried!
BS
Thanks Blacksheep - and welcome to the board!
I'm guessing expensive to replace?
Best Regards, Phil
Hi Phil,
The 2 that won't go full speed, Possibly bad capacitor or just a bad motor..
If you would like to test the capacitors, be sure to discharge them before toutching them! Ground them out after you disconnectd the power.
With an Ohm meter, check the value and compare it with the printing on the side. An open reading will be bad and full continunity is also bad.
If the capacitor is good, the motor is bad.
Put more oil on the shafts and spinn the hell out of em... "hale Mary" lol
Good Luck
Nick-
Quote from: muddog16 on April 21, 2008, 12:22:16 PM
Three units at one time, I guess its possible, but I'd check my neutral coming in to the bus, I've been wrong before but its easier checking one thing first than 3! Good luck!
Thanks Pat - checking the neutral when it comes into the bus - since symptoms are same for both shore A/C power & generator, I would be looking for a place where those two share the same lines.
Could you describe how I check this neutral? Thank you, Phil
Now I'm confused - Phil said:
"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"
If your neutral is bad the fans can run for a while (depending on how your bonded) but will stop or trip the breaker - the compressor will humm but not cool - If you run the one unit that is now working for a while (10 or 15 minutes) but it does not cool or cools and then warms up I'd be back to the neutral as being the culprit -
Now if your compressors are having problems starting just get your self some hard starts and wire them in line with the capacitors and see if that works - we have units that sit for a long while and the hard starts work 99% of the time getting them cranked again - HTH
BTW - Did you turn the units on one at a time (only one running at a time) or turn them all on at once?
With the power on I'd first check incoming voltage, neutrals can drive you silly trying to find a loose connection, if the voltage looked normal, then I'd turn the power off and check all of the connections even remaking them. All of the bouncing our buses go through could possibly make for loose or bad connections! Being in the environment of bussing would be to our advantage to do a yearly preventive maintenance in these areas just for that reason! Trouble shooting is simple divide and conquer, first go to the source and check, then just keep splitting circuit in half until you find the problem! Never assume anything in electrical trouble shooting, Phil another thing would be to check the receptacle that feeds your bus or the cord even. I know this didn't give actual specifics but the idea of how should help. The most difficult problem in electricity is trying to find a problem that won't show itself, a broken wire, or a component that isn't completely broken, they can humble the most experienced electrician! Good luck Phil!
Quote from: niles500 on April 21, 2008, 08:16:12 PM
Now I'm confused - Phil said:
"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"
If your neutral is bad the fans can run for a while (depending on how your bonded) but will stop or trip the breaker - the compressor will humm but not cool - If you run the one unit that is now working for a while (10 or 15 minutes) but it does not cool or cools and then warms up I'd be back to the neutral as being the culprit -
Now if your compressors are having problems starting just get your self some hard starts and wire them in line with the capacitors and see if that works - we have units that sit for a long while and the hard starts work 99% of the time getting them cranked again - HTH
BTW - Did you turn the units on one at a time (only one running at a time) or turn them all on at once?
Greetings Niles,
Fans don't run at all on the two remaining A/Cs which are malfunctioning. The recovered roof A/C - both the fan, and condenser run, cool, w/o any problem now. I did run it for about 10 minutes. Very nice, cool. All I get when I turn on the fan on the dead units is a VERY quiet hum. No fan activity. If I turn the a/c knob to engage the compressor, then I hear a much louder hum. Still no fan. That is where the
"I guess" the compressor runs statement came from.
BTW, I should add that these units are not tied together by any central thermostat. All run, and are controlled, separately.
On - getting the hard starts and wiring them inline with the capacitors - would this be something for a seasoned professional to do, or something I could learn? I claim total ignorance here. I don't know what a hard start is or where to find the capacitors! If I can learn this, I can post pix, to the BBS,etc., for further guidance & questions.
Thanks again! Phil
Hi Phil,
The hard starts are for hard compressor starting only!
Nick-
Phil,
Revert back to my post on how to check the capacitors on the fans..
Keep spinning and oiling those motors ;D....
Nick-
Quote from: muddog16 on April 22, 2008, 03:29:40 AM
With the power on I'd first check incoming voltage, neutrals can drive you silly trying to find a loose connection, if the voltage looked normal, then I'd turn the power off and check all of the connections even remaking them. All of the bouncing our buses go through could possibly make for loose or bad connections! Being in the environment of bussing would be to our advantage to do a yearly preventive maintenance in these areas just for that reason! Trouble shooting is simple divide and conquer, first go to the source and check, then just keep splitting circuit in half until you find the problem! Never assume anything in electrical trouble shooting, Phil another thing would be to check the receptacle that feeds your bus or the cord even. I know this didn't give actual specifics but the idea of how should help. The most difficult problem in electricity is trying to find a problem that won't show itself, a broken wire, or a component that isn't completely broken, they can humble the most experienced electrician! Good luck Phil!
Greetings Pat,
I will keep the divide the circuit in half concept in mind as I work through this. Is there a technique to finding the neutral problems? So far, all my readings show steady voltage. No matter where I am testing, and what the power source is ( land or generator ) - always 121 - 122 volts.
Thanks again! Phil
Quote from: Nick Badame Refrig. Co. on April 22, 2008, 05:47:04 AM
Phil,
Revert back to my post on how to check the capacitors on the fans..
Keep spinning and oiling those motors ;D....
Nick-
Will do Nick, covers will come back off again. I did get the fans to spin very freely & had them pretty oiled up, but will re-do that process on the malfunctioning A/C units.
Thank you! Phil
Phil, I am electrically challenged, once I found the capacitors and starters, I simply switched them from the AC that worked to the dead AC and from the dead AC to the working AC. (they are all the same model right?) Time consuming but eliminates tring to figure out if I am useing ohm meter right, am I on the right scale etc. My next step was to switch the circut boards around.
HTH Jim
Jim, I am very impressed that you figured all that out. Nice work for one of us electrically challenged. ;D ;D ;D
Kind Regards, Phil
Nick,
Are the fan motors on those rooftops capacitor start? I thought they were just shaded pole motors. I don't remember seeing a capacitor when I cleaned mine last year but, then again, I can't remember where I put the cars keys either! ;D
I'm just asking. It would be a shame for Phil to further complicate the situation by looking for something that isn't there.
TOM
Hi Phil,
I don't want to offend you, but your posts haven't made it clear, to me anyway, that you have oiled the bearings at BOTH ends of the motor. If you haven't, please do that before spending a lot of time checking for electrical problems. You have proven that the blower motor shafts were stuck so it makes sense to work from there.
Last fall I had the same problem on one of our roof A/C units. The solution was to free the shaft and oil the bearings. If you didn't leave your units turned on long enough to burn something out you should have the same results.
Good luck, Sam 4106
Quote from: oldmansax on April 22, 2008, 08:34:16 AM
Nick,
Are the fan motors on those rooftops capacitor start? I thought they were just shaded pole motors. I don't remember seeing a capacitor when I cleaned mine last year but, then again, I can't remember where I put the cars keys either! ;D
I'm just asking. It would be a shame for Phil to further complicate the situation by looking for something that isn't there.
TOM
Hi Tom,
Most of the roof units have "run" capacitors on the fan motors not start.
Shaded pole motors are too expensive for Dometic and others to use.....Lol
The caps should be in the control box if they have any.
Nick-
About shaded pole (SP) and a permanent split capacitor (PSC):
http://en.allexperts.com/q/Heating-Air-Conditioning-696/Blower-motor-capacitor.htm
Quick starting and use about half the electrical power energy as SP motor is the reason not being use.
About "humming" noise is same as either binding shaft (dry & little rusted) or capacitor is bad or very low electrical power. So do the simple things first at least 110 volts (the lower the voltage, the longer it hums before it spins or never, spins freely and capacitor.
FWIW
Sojourn for Christ, Jerry
PS...I used to rewind motors and moist proof sump-pump motor as well.
I was a NCO Work Center Super for many years. My instruction was that "if you can't get the problem to 'FOLLOW' a component/subassemby when you switch them with a working unit....then you did not prove what went wrong." Sometimes everything worked after they did the switch, JJR had the real inside track when he suggested that "a known working part" be substituted in for the suspect part. If the malfunctioning part starts to work....put the suspected bad part in what was the good system and PROVE it was the culprit by showing that the previously good sys is now bad. Switching the caps was a real good idea and I would try that with both units and I would make sure that all caps work in you "good" system.
When you turn the bad sys on can you give the fan a spin with your finger? Not enough torque at start to cut anything off completely. ;D
They keep bringing you back to "oil the shafts" so they must know somthing. Does the shaft on the good unit spin as freely as the shafts on the bad units? ???
Good luch here, you are 30% there. My ac unit, built in 73, still works fine. Front one was replaced twice that I know of.
John
Just curious. When you turn on the bad units and you get a hum, did you try spinning the fan by hand to see if it would kick in? I have had humming motors that would start running with a spin which added to the diagnostic information available.
Quote from: Nick Badame Refrig. Co. on April 22, 2008, 09:03:27 AM
Most of the roof units have "run" capacitors on the fan motors not start.
Shaded pole motors are too expensive for Dometic and others to use.....Lol
Nick,
I'm not sure I understand this comment -- shaded pole motors are the absolute cheapest single-phase induction motors made.
FWIW, Dometic units are capacitive-start. They have both run and start capacitors.
A representative wiring diagram can be found in the Dometic user manual. One can be found on-line here: http://www.dudesrv.com/pdfs/DometicBriskAirUMan.pdf (http://www.dudesrv.com/pdfs/DometicBriskAirUMan.pdf)
(Phil, if you don't have the manual already, you might want to download the one linked above.)
HTH,
-Sean
Sean,
If read the diagram a little closer you will see that the start capacitor is wired to the compressor and the run capacitor is wired to the fan & Comp..
The combo Run capacitor has 3 terminals, "H" hermetic, "C" common, "F" fan.
Nick-
Oh, Phil said he has Penguins, not Brisk Airs.
Quote from: Nick Badame Refrig. Co. on April 22, 2008, 01:50:03 PM
If read the diagram a little closer you will see that the start capacitor is wired to the compressor and the run capacitor is wired to the fan & Comp..
Yes, sorry, I was talking about the compressor, which I understand also not to be starting.
In any case, the fan motor is still capacitive-start, just not with the extra start capacitor. (The "run" capacitor is there to provide differential field for starting.)
Quote
Oh, Phil said he has Penguins, not Brisk Airs.
The manual I linked is the Penguin Manual (not sure why its file name is BriskAir, maybe same manual) -- you can also find it linked on the Penguin web page here: http://www.dometicusa.com/climate.php?product=50 (http://www.dometicusa.com/climate.php?product=50)
These should be the correct diagrams for Phil's Penguins with the ADB's.
-Sean
""On - getting the hard starts and wiring them inline with the capacitors - would this be something for a seasoned professional to do, or something I could learn? I claim total ignorance here. I don't know what a hard start is or where to find the capacitors! If I can learn this, I can post pix, to the BBS,etc., for further guidance & questions""
Phil - first off I want to apologize, I replied once to this ? and it must have gone to cyber space - Nick is right if your compressors are working you don't need hard starts - they are like "super" capacitors, if your commpressor is locked down from sitting or wear they will usually get them started.
On the neutral issue - I have seen cases where the neutral is bad upstream and due to how the bond was made the system uses the ground as a neutral (a very poor neutral), small loads can work marginaly this way but when you apply a big load that is when you find out you have a neutral problem - I don't know how you store your bus but it could be as simple as a rodent munching or possibly you used some AL wire?
It is quite possible (not so probable) that all three are just fan motors/shafts seizing but brought to my mind this possibility - If the oiling suggested doesn't work we can always revisit this. HTH
Quote from: Sam 4106 on April 22, 2008, 08:37:07 AM
Hi Phil,
I don't want to offend you, but your posts haven't made it clear, to me anyway, that you have oiled the bearings at BOTH ends of the motor. If you haven't, please do that before spending a lot of time checking for electrical problems. You have proven that the blower motor shafts were stuck so it makes sense to work from there.
Last fall I had the same problem on one of our roof A/C units. The solution was to free the shaft and oil the bearings. If you didn't leave your units turned on long enough to burn something out you should have the same results.
Good luck, Sam 4106
Offend me Sam? HaHaHa - I KNOW I don't know what I'm talking about. ;D :D ;D I appreciate your taking the time to offer suggestions & your experience.
I have only oiled the bearings at ONE end of the motor. Didn't even know I could oil both ends. I'll look to do that. I do note though that right now the blowers spin quite freely. Wouldn't the motor have to be very weak right now to not be able to spin the cages that spin freely?
Thanks Sam! Phil
Quote from: Lin on April 22, 2008, 12:51:57 PM
Just curious. When you turn on the bad units and you get a hum, did you try spinning the fan by hand to see if it would kick in? I have had humming motors that would start running with a spin which added to the diagnostic information available.
Hi Lin,
No, I was afraid to try that - It's really difficult to get my hand up there from inside the coach. and if I ran up the ladder w/the motor malfunctioning, I was afraid I'd burn out what was left of the motors. Maybe if I used a stick from inside to give the blower a bit of a nudge. I'll post back what happens.
Thank you, Phil
Ha! Where are the best bunch of busnuts anywhere??
RIGHT HERE - That's where!! ;D ;D ;D
I think oiling the shaft. and using a stick (yeah, I'm a chicken & don't know what I'm doing) to move the squirrel cage while turning on the blower made the final difference. Turned on the motor, gave a push on the cage w/ a stick, cage stuck for a bit, then spun freely. So, I miscalculated yesterday how freely they spun when I was spinning 'em from the roof. They are running right now for a good 10 minutes. I'll go up in daylight on the roof & oil both sides of the shaft & make sure all good.
Same story on rear a/c.
Middle A/C still worked fine today after running for 10 or so minutes yesterday. ;D
What a fanstastic group - I really appreciate every suggestion. I have read them ALL carefully and have learned a tremendous amount about not just my a/c units, maintaining & running them through the winter, but also circuit & electrical system troubleshooting. I was totally resigned to the fact that I would be buying 2 roof a/c units + labor. So some kind of $1,500 bill was looking at me in the face. But NO!
Thanks Team!
Kind Regards, Phil
I know how you feel Phil!!!! These guys have save me numerous times.
Coool Phil
You have saved us with this board MANY times and now the board saved you
You work magic in cyber space and it comes back and helps you
What a great bunch of people here
Melbo