[GreenKeys] Model 35ASR TD Motor Woes

[Justin Scott]

Howdy,

A couple things - first, does anyone have a newer or older version of 6000 WD for the 35 ASR than I have?  I am looking at issue 21 of the issue control record (4-10-72) because 6000WD-C3 (same rev date) calls out Note 13 which does NOT appear on this issue control, which ends at Note 12.

This is in regards to "C1", the capacitor for the TD motor- -C3 calls out two C1's, one at 3 MFD and another at 4 MFD - seems trivial, I know, but considering this is a run capacitor for an AC motor, a little difference in capacitance can result in a lot of heat (but that much difference?  I suspect not!)

Anyhow - I expect that the note calls out the difference being related to 35A46 and 35B46 TD units, which use different motors (maybe there's others, but these are the two I have).

Problem here is that last night, while letting the 35 ASR run copy to flush out any remaining demons, the run capacitor for the TD motor went "foomf" (that's a technical term).

I realized this when, after it'd been running for quite some time, I stepped out of my office into the rest of the house and noticed something smelled hot.  Quickly sourced the hot smell back to the 35 ASR, which was still running fine.  Popping the TU cover revealed a much increased smell and wisps of smoke.  Popping the whole cover up showed a fine stream of smoke coming out of the TD motor vents.  Then I noticed this foomf:

http://i.imgur.com/ACHVKkN.jpg
http://i.imgur.com/vX7Nq33.jpg
http://i.imgur.com/SRqGPWS.jpg

Recorded thermals at the time before shutting down, and found hot spots up to 315F (157C) on the motor.  The motor is stamped "60C Continuous".  I have no thermal record prior to this event.

This morning, I replaced the cap with one sourced from my local HVAC supply, shorter, but identical otherwise.

Motor spins effortlessly when powered off, starts up immediately, makes no unusual noises while running.

With the covers open, I've so far observed a constant operating temp around 190F (88C) at the peaks, and 170F (77C) on the motor cover in general.  With the covers closed, I've observed up to 220F (104C) in the hot spots, but as of yet have not let it run until I've determined a plateau on the temps.  Will be doing that next.

Does anyone know if the 35A46's motor just runs hot?  Or have I damaged it from last night and now it will be hot until rebuilt or replaced?  If it helps, I can pull the part # from the motor itself, i'm sure it was used elsewhere.

If it's damaged, I'd like to replace or rebuild it.  If it's a matter of needing that extra microfarad of capacitance to shift the phase over just enough to keep it from getting hot, I'm happy to do that too... The one I replaced it with is +/- 5% @ 3 MFD.  Of course the supply house closed for the day before I thought I'd like to go back and get a 4 MFD unit to see what the temp differences would be.

At this point, I'm running a 30 minute timer, and popping the main cover to take temperature readings at 30 minutes intervals.  It will either plateau, or continue to climb until it starts to smoke.  Either way, I'll probably know within a couple hours. :)

cheers,
dj
N7XDJ