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Author Topic: All 3 roof airs failed simultaneously?  (Read 4098 times)
JackConrad
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« Reply #15 on: April 21, 2008, 11:37:44 AM »

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
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« Reply #16 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!
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« Reply #17 on: April 21, 2008, 01:32:46 PM »

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
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« Reply #18 on: April 21, 2008, 02:45:22 PM »

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
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« Reply #19 on: April 21, 2008, 03:09:42 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!

>>>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?
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« Reply #20 on: April 21, 2008, 06:30:29 PM »

Hi folks, Thanks for all the responses!  It is very much appreciated.   Grin

I just returned from the bus as Nick was reporting BBS problems - and I was actually working on my bus.   Cheesy

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.   Angry  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.  Cheesy

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
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« Reply #21 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
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« Reply #22 on: April 21, 2008, 07:19:07 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
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« Reply #23 on: April 21, 2008, 07:21:32 PM »

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-
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« Reply #24 on: April 21, 2008, 07:22:17 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
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« Reply #25 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?
« Last Edit: April 21, 2008, 08:25:37 PM by niles500 » Logged

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« Reply #26 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!

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Pat

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« Reply #27 on: April 22, 2008, 05:15:35 AM »

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
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« Reply #28 on: April 22, 2008, 05:45:31 AM »

Hi Phil,

The hard starts are for hard compressor starting only!

Nick-
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« Reply #29 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 Grin....

Nick-
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