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Mr Slim - PUH (outside unit) Kitch 09-22-2007
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Posted by -zero on September 25, 2007, 5:16 pm

.

>> - Show quoted text -

> The power was shut off several times in order to check thermisters,
> safety switches, compressor contactor, compressor and finally changing
> the 208v legs when it finally ran ok. I don't understand why changing
> single-phase legs on the outdoor unit had anything to do with it.
> Before the unit came on line, the P8 did clear but after 9 minutes of
> outdoor failure it then goes back into the P8 warning. When the
> inside unit called for cooling during the 9 minutes I did get correct
> DC voltage at S1, S2, and S3. I also had 208v (wired 208v which as
> you know is ok for this unit) at the junction plug for the outdoor
> motor coming out of the board. The fan did not start. I hooked up
> another test motor to the plug, which uses a much less amp draw than
> the unit's motor and it did not start as well. In thought I may have
> had a back bleed of voltage, but due to the internal "FC" (fan
> controller in the board itself) it could not be checked. In other
> words, it mystifies other mechanics, Mitsubishi and myself. I went
> ahead and installed a new board with the same results. I do believe
> I'd rather have a "Mini-Chiller". I appreciate both of your input.
> "Mysticalbishi"
.
>
> Kitch

If you swap the 208v line leads back, the failures should all return
if the power supply is the problem.

Wait,,, 208v single phase!???? Where are you getting your power
supply from? A common 240/3phase is 120,208,120 to ground.
Are you using a single 208 w/ a ground leg? What voltage
do have w/each leg to ground?

-zero



>



Posted by The Freon Cowboy on September 25, 2007, 5:45 pm
ahhh , your getting the picture i had ;-)



Posted by Kitch on September 25, 2007, 6:05 pm
wrote:
>
> .
>
>
>
>
>
>
>
> >> - Show quoted text -
> > The power was shut off several times in order to check thermisters,
> > safety switches, compressor contactor, compressor and finally changing
> > the 208v legs when it finally ran ok. I don't understand why changing
> > single-phase legs on the outdoor unit had anything to do with it.
> > Before the unit came on line, the P8 did clear but after 9 minutes of
> > outdoor failure it then goes back into the P8 warning. When the
> > inside unit called for cooling during the 9 minutes I did get correct
> > DC voltage at S1, S2, and S3. I also had 208v (wired 208v which as
> > you know is ok for this unit) at the junction plug for the outdoor
> > motor coming out of the board. The fan did not start. I hooked up
> > another test motor to the plug, which uses a much less amp draw than
> > the unit's motor and it did not start as well. In thought I may have
> > had a back bleed of voltage, but due to the internal "FC" (fan
> > controller in the board itself) it could not be checked. In other
> > words, it mystifies other mechanics, Mitsubishi and myself. I went
> > ahead and installed a new board with the same results. I do believe
> > I'd rather have a "Mini-Chiller". I appreciate both of your input.
> > "Mysticalbishi"
> .
>
> > Kitch
>
> If you swap the 208v line leads back, the failures should all return
> if the power supply is the problem.
>
> Wait,,, 208v single phase!???? Where are you getting your power
> supply from? A common 240/3phase is 120,208,120 to ground.
> Are you using a single 208 w/ a ground leg? What voltage
> do have w/each leg to ground?
>
> -zero
>
>
>
> - Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -

Sorry, I should have stated that this isn't residential power. It is
208 single phase with ground wire for unit protection. I do get 115v
from each leg to ground, which is normal. I have borrowed power from
the disconnect from many rooftop's or any other unit I may find
close. After removing the unit side supply where I could put one clip
to power and one to ground, as long as I don't over amp. This is why
I don't understand the switching of the two legs on 208 single phase
had anything to do with it, surely Mitzubishi does not understand
rhyme or reason why it worked. I did convey with him that the DC
voltage being polar and coming off the outside unit, may have had
everything to do with the 4 lead secondary 12VDC. He disclaimed that,
but it is the only reason I can come up with or at least the "control
board" can.

Kitch



Posted by Zyp on September 25, 2007, 7:15 pm
Kitch wrote:
> wrote:
>>
>> .
>>
>>
>>
>>
>>
>>
>>
>>>> - Show quoted text -
>>> The power was shut off several times in order to check thermisters,
>>> safety switches, compressor contactor, compressor and finally
>>> changing the 208v legs when it finally ran ok. I don't understand
>>> why changing single-phase legs on the outdoor unit had anything to
>>> do with it. Before the unit came on line, the P8 did clear but
>>> after 9 minutes of outdoor failure it then goes back into the P8
>>> warning. When the inside unit called for cooling during the 9
>>> minutes I did get correct DC voltage at S1, S2, and S3. I also had
>>> 208v (wired 208v which as you know is ok for this unit) at the
>>> junction plug for the outdoor motor coming out of the board. The
>>> fan did not start. I hooked up another test motor to the plug,
>>> which uses a much less amp draw than the unit's motor and it did
>>> not start as well. In thought I may have had a back bleed of
>>> voltage, but due to the internal "FC" (fan controller in the board
>>> itself) it could not be checked. In other words, it mystifies
>>> other mechanics, Mitsubishi and myself. I went ahead and installed
>>> a new board with the same results. I do believe I'd rather have a
>>> "Mini-Chiller". I appreciate both of your input. "Mysticalbishi"
>> .
>>
>>> Kitch
>>
>> If you swap the 208v line leads back, the failures should all
>> return if the power supply is the problem.
>>
>> Wait,,, 208v single phase!???? Where are you getting your power
>> supply from? A common 240/3phase is 120,208,120 to ground.
>> Are you using a single 208 w/ a ground leg? What voltage
>> do have w/each leg to ground?
>>
>> -zero
>>
>>
>>
>> - Hide quoted text -
>>
>> - Show quoted text -- Hide quoted text -
>>
>> - Show quoted text -
>
> Sorry, I should have stated that this isn't residential power. It is
> 208 single phase with ground wire for unit protection. I do get 115v
> from each leg to ground, which is normal. I have borrowed power from
> the disconnect from many rooftop's or any other unit I may find
> close. After removing the unit side supply where I could put one clip
> to power and one to ground, as long as I don't over amp. This is why
> I don't understand the switching of the two legs on 208 single phase
> had anything to do with it, surely Mitzubishi does not understand
> rhyme or reason why it worked. I did convey with him that the DC
> voltage being polar and coming off the outside unit, may have had
> everything to do with the 4 lead secondary 12VDC. He disclaimed that,
> but it is the only reason I can come up with or at least the "control
> board" can.
>
> Kitch

I'm inclined to go with *zero's* thinking. When you measure the line to
ground [either L1 or L2] are you measuring with an open disconnect? It
seems to me if you single legging from a three phase supply, switching the
legs could have "funny" reaction with it.

--
Zyp



Posted by The Freon Cowboy on September 26, 2007, 7:07 am
i think zyp has a point , are you measuring voltage with disconecct open or
closed ?

cant help but wonder if your not tied into a "crazy" leg
this is three phase service right , your just using two legs ?
some areas still have this type of service ,ithink its called delta t
darn leg will
swing from 90 to 180 volts , depending on load,
just a thought ?


>Kitch wrote: > On Sep 25, 5:16 pm, "-zero"
wrote:p>>>> "Zyp"
was shut off several times in order to check thermisters,>>> safety switches,
compressor contactor, compressor and finally>>> changing the 208v legs when
it finally ran ok. I don't understandN>>> why changing single-phase legs on
the outdoor unit had anything to>>> do with it. Before the unit came on line,
the P8 did clear butp>>> after 9 minutes of outdoor failure it then goes back
into the P8>>> warning. When the inside unit called for cooling during the
9p>>> minutes I did get correct DC voltage at S1, S2, and S3. I also hadp>>>
208v (wired 208v which as you know is ok for this unit) at the:>>> junction
plug for the outdoor motor coming out of the board. The>>> fan did not
start. I hooked up another test motor to the plug,>>> which uses a much less
amp draw than the unit's motor and it didš>>> not start as well. In thought I
may have had a back bleed ofp>>> voltage, but due to the internal "FC" (fan
controller in the boardE>>> itself) it could not be checked. In other words,
it mystifies">>> other mechanics, Mitsubishi and myself. I went ahead and
installedØ>>> a new board with the same results. I do believe I'd rather have
a>>> "Mini-Chiller". I appreciate both of your input. "Mysticalbishi"S>>
.p>>T>>> Kitch>>p>> If you swap the 208v line leads back, the failures
should allW>> return if the power supply is the problem.>>p>> Wait,,, 208v
single phase!???? Where are you getting your powerp>> supply from? A common
240/3phase is 120,208,120 to ground. >> Are you using a single 208 w/ a ground
leg? What voltage
>> do have w/each leg to ground?e>>Ê>> -zerof>>v>>>>p>> - Hide quoted text
-p>>h>> - Show quoted text -- Hide quoted text -j>>^>> - Show quoted text
-ˆ>p> Sorry, I should have stated that this isn't residential power. It isp>
208 single phase with ground wire for unit protection. I do get 115vp> from
each leg to ground, which is normal. I have borrowed power fromp> the
disconnect from many rooftop's or any other unit I may findz> close. After
removing the unit side supply where I could put one clip~> to power and one to
ground, as long as I don't over amp. This is why> I don't understand the
switching of the two legs on 208 single phaseD> had anything to do with it,
surely Mitzubishi does not understandÊ> rhyme or reason why it worked. I did
convey with him that the DC`> voltage being polar and coming off the outside
unit, may have hadÓ> everything to do with the 4 lead secondary 12VDC. He
disclaimed that,“> but it is the only reason I can come up with or at least
the "control—> board" can.>˜> Kitch˜pI'm inclined to go with *zero's*
thinking. When you measure the line to zground [either L1 or L2] are you
measuring with an open disconnect? It  seems to me if you single legging from
a three phase supply, switching the ¤legs could have "funny" reaction with
it.½-- ìZyp




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