[RFI] Trane heat pump RFI (Wes Stewart)

Wes Stewart n7ws at yahoo.com
Wed Jul 8 17:42:14 EDT 2020

 First, I can't explain the question marks, I'm composing this in Yahoo Mail.  I normally use Thunderbird for other email addresses but default to this one as a spam gathering address.  I suppose I should change my subscription address.
That said, I did lay my hands on a schematic for this thing.  There isn't a kick start kit per se, the starting relay is factory installed and is what the HVAC trade calls a "potential relay", one that is powered by the back EMF from the motor start winding (in this case windings, since it's a dual compressor device).
By inspection, I'm now suspecting a leaky run capacitor since enough leakage through it would pull in the start (potential) relay. Since this is an oscillating condition, I'm assuming some LC involvement  The starting capacitor is already leaky by virtue of a resistor across it and since starting is not an issue, I'm going to the run cap.  However, it's currently 107 degrees F outside, and forecast to be 114 by Sunday, and I'm under orders from my better half to not mess with this until the heat wave is over (probably about October).  So more rigorous troubleshooting will have to wait.

Nevertheless, I will have a cap in hand tomorrow just in case.
Wes  N7WS

    On Wednesday, July 8, 2020, 10:17:11 AM MST, krgoodwin at comcast.net <krgoodwin at comcast.net> wrote:  
 I wonder if the kick start (relay) kit (circuit) might be the source.  It
would be energized during non-operational periods and drop out within
seconds of your heat pump turning on.  The kits normally use a relay to
insert the additional kick start capacitor at turn on and then remove it
when it is time for normal run capacitor to be inserted into the scheme.  I
am an EE but I do play with my HVAC systems and I have found the start/run
capacitor circuits to be a module that fails; at least, it has failed for
me.  In my case, the kick start capacitor had started to leak causing a
different start up noise from the compressor.  After all who but an engineer
listens to his HVAC compressor start and cringe every time he hears the kick
start capacitor kick the crap out of the compressor at start up.  Maybe
temporarily removing the kick start kit which would pull the power from the
relay I think you are mentioning, which might be an investigative step.  Of
course I am guessing at your specific situation which is made more difficult
since either you or my email program keeps inserting a question mark after
some character like quotation marks.  Maybe Mr. Gates can explain this odd
blog email decoding outcome to me some day when I have even more time to
waste. I use Outlook BTW.  Ken K5RG

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