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Posted by Noon-Air on July 11, 2006, 7:57 am
show/hide quoted text
> Noon-Aire needs to jump in here.
>> I went out tonight to look at a small Rheem split system. I think it was
>> 2 ton manufactured in 1991. Copeland Hermi.
>> The compressor wasn't running, OFM was.
>> Single phase 240 V.
>> I kill the power and check the compressor. Good resistance from each
>> terminal to one another. About 1 ohm between the two hots and 4 ohms
>> from one to the start winding. No shorts to ground.
>> This setup has a dual cap for the fan and comp. There also appears to be
>> a factory hard-start built in. The hard-start relay showed closed (as it
>> should) with the system powered down.
> I don't recall ever seeing a factory hard start kit on a 2 ton Rheem unit,
> especially from 1991. Something doesn't jive here. I'd rip it out and
> install a SPP6 or equalivent.
>> Put power back to the thing and I don't hear a darn thing but it won't
>> run. I never even heard it try to start. 240 V to both run terminals and
>> 240 V between one run and the start. The other run to start showed about
> 15.
>> I don't know if the internal O/L's are working that fast or what's up. I
>> suspect a start or run cap... but I thought I'd get some more opins.
>> I didn't have the time rip the cap out of the cabinet... Rheem made it a
>> pain (Payne for Johnny) on this unit. I'll check it next tomorrow or
>> so...
>> Why the heck would a internal trip that fast? I can't even see a current
>> draw when it should be trying to start.
>> Any suggestions?
>> Jake
>
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Posted by Noon-Air on July 11, 2006, 8:02 am
> Noon-Aire needs to jump in here.
Umm.... ok
show/hide quoted text
>> I went out tonight to look at a small Rheem split system. I think it was
>> 2 ton manufactured in 1991. Copeland Hermi.
>> The compressor wasn't running, OFM was.
>> Single phase 240 V.
>> I kill the power and check the compressor. Good resistance from each
>> terminal to one another. About 1 ohm between the two hots and 4 ohms
>> from one to the start winding. No shorts to ground.
I have one like that to replace in a 4 ton Goodman today
show/hide quoted text
>> This setup has a dual cap for the fan and comp. There also appears to be
>> a factory hard-start built in. The hard-start relay showed closed (as it
>> should) with the system powered down.
Need model and serial number to see if it was a factory installed accessory
show/hide quoted text
> I don't recall ever seeing a factory hard start kit on a 2 ton Rheem unit,
> especially from 1991. Something doesn't jive here. I'd rip it out and
> install a SPP6 or equalivent.
If its immediately throwing the breaker, the SPP6 isn't going to help.
show/hide quoted text
>> Put power back to the thing and I don't hear a darn thing but it won't
>> run. I never even heard it try to start. 240 V to both run terminals and
>> 240 V between one run and the start. The other run to start showed about
> 15.
It sounds to me like internally shorted windings.
show/hide quoted text
>> I don't know if the internal O/L's are working that fast or what's up. I
>> suspect a start or run cap... but I thought I'd get some more opins.
>> I didn't have the time rip the cap out of the cabinet... Rheem made it a
>> pain (Payne for Johnny) on this unit. I'll check it next tomorrow or
>> so...
>> Why the heck would a internal trip that fast? I can't even see a current
>> draw when it should be trying to start.
Shorted/grounded windings
show/hide quoted text
>> Any suggestions?
>> Jake
>
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Posted by Jake on July 11, 2006, 7:56 pm
>>> This setup has a dual cap for the fan and comp. There also appears to be
>>> a factory hard-start built in. The hard-start relay showed closed (as it
>>> should) with the system powered down.
>
> Need model and serial number to see if it was a factory installed accessory
I'll try and get that tomorrow... if I can make it back over there.
show/hide quoted text
>
>> I don't recall ever seeing a factory hard start kit on a 2 ton Rheem unit,
>> especially from 1991. Something doesn't jive here. I'd rip it out and
>> install a SPP6 or equalivent.
>
> If its immediately throwing the breaker, the SPP6 isn't going to help.
There is NO breaker or fuse trip. The compressor doesn't draw any
current even though I can measure resistance across ALL the windings
initially. The compressor wasn't too terribly hot.
show/hide quoted text
>>> Put power back to the thing and I don't hear a darn thing but it won't
>>> run. I never even heard it try to start. 240 V to both run terminals and
>>> 240 V between one run and the start. The other run to start showed about
>> 15.
>
> It sounds to me like internally shorted windings.
The measurements I gave initially sounded about right for that size
compressor. If I had internal short.... I should get an external OCP
trip, shouldn't I?
show/hide quoted text
>>> Why the heck would a internal trip that fast? I can't even see a current
>>> draw when it should be trying to start.
>
> Shorted/grounded windings
Steve, I already measured (and even megged) the windings. I don't find a
short anywhere. The compressor has V at the terminals but doesn't draw
any current. I'm going for Paul's thought that the connects are dirty or
loose. A condenser sitting outside for that long could stand to have
that crap cleaned up, anyhow.
My real question, I guess... was how fast a internal O/L trip would
occur... and thus indicate a mechanical problem in the compressor.. or a
failure to start due to bad caps?
Jake
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Posted by Barry on July 11, 2006, 11:07 pm
wrote:
show/hide quoted text
>>>> This setup has a dual cap for the fan and comp. There also appears to be
>>>> a factory hard-start built in. The hard-start relay showed closed (as it
>>>> should) with the system powered down.
>>
>> Need model and serial number to see if it was a factory installed accessory
>I'll try and get that tomorrow... if I can make it back over there.
>>
>>> I don't recall ever seeing a factory hard start kit on a 2 ton Rheem unit,
>>> especially from 1991. Something doesn't jive here. I'd rip it out and
>>> install a SPP6 or equalivent.
>>
>> If its immediately throwing the breaker, the SPP6 isn't going to help.
>There is NO breaker or fuse trip. The compressor doesn't draw any
>current even though I can measure resistance across ALL the windings
>initially. The compressor wasn't too terribly hot.
>>>> Put power back to the thing and I don't hear a darn thing but it won't
>>>> run. I never even heard it try to start. 240 V to both run terminals and
>>>> 240 V between one run and the start. The other run to start showed about
>>> 15.
>>
>> It sounds to me like internally shorted windings.
>The measurements I gave initially sounded about right for that size
>compressor. If I had internal short.... I should get an external OCP
>trip, shouldn't I?
>>>> Why the heck would a internal trip that fast? I can't even see a current
>>>> draw when it should be trying to start.
>>
>> Shorted/grounded windings
>Steve, I already measured (and even megged) the windings. I don't find a
>short anywhere. The compressor has V at the terminals but doesn't draw
>any current. I'm going for Paul's thought that the connects are dirty or
>loose. A condenser sitting outside for that long could stand to have
>that crap cleaned up, anyhow.
>My real question, I guess... was how fast a internal O/L trip would
>occur... and thus indicate a mechanical problem in the compressor.. or a
>failure to start due to bad caps?
>Jake
How bout an open internal overload.
Barry
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Posted by ~^Johnny^~ on July 12, 2006, 1:41 am
On Wed, 12 Jul 2006 03:09:02 GMT, .p.jm@see_my_sig_for_address.com
wrote:
show/hide quoted text
>He said he had Ohm readings in all directions.
If it shows continuity with a DVM or VOM, but goes to high impedance
with mains applied, that tells me something...
rectification, most likely.
Try the ohmmeter on each pair of terminals with meter leads switched.
Corroded, overheated, or otherwise buggered connections cause weird
symptoms.
Pull the wires OFF the compressor terminals and take continuity, with
a good DVM in "diode test mode", swapping test leads on each reading.
Bad connections which develop "parasitic rectifier junctions" can ohm
out fine, but go "open" when hit with higher current. As far as the
compressor is concerned, you got to isolate the problem between
=internal= and =external=. If nothing gets warm to the touch on the
outside, and current draw is at or near zilch with power (full
voltage) applied to the compressor, it's probably (99% positively)
internal. ;`(
Compressors do not always get hot when they go bad.
--
-john
wide-open at throttle dot info
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>> I went out tonight to look at a small Rheem split system. I think it was
>> 2 ton manufactured in 1991. Copeland Hermi.
>> The compressor wasn't running, OFM was.
>> Single phase 240 V.
>> I kill the power and check the compressor. Good resistance from each
>> terminal to one another. About 1 ohm between the two hots and 4 ohms
>> from one to the start winding. No shorts to ground.
>> This setup has a dual cap for the fan and comp. There also appears to be
>> a factory hard-start built in. The hard-start relay showed closed (as it
>> should) with the system powered down.
> I don't recall ever seeing a factory hard start kit on a 2 ton Rheem unit,
> especially from 1991. Something doesn't jive here. I'd rip it out and
> install a SPP6 or equalivent.
>> Put power back to the thing and I don't hear a darn thing but it won't
>> run. I never even heard it try to start. 240 V to both run terminals and
>> 240 V between one run and the start. The other run to start showed about
> 15.
>> I don't know if the internal O/L's are working that fast or what's up. I
>> suspect a start or run cap... but I thought I'd get some more opins.
>> I didn't have the time rip the cap out of the cabinet... Rheem made it a
>> pain (Payne for Johnny) on this unit. I'll check it next tomorrow or
>> so...
>> Why the heck would a internal trip that fast? I can't even see a current
>> draw when it should be trying to start.
>> Any suggestions?
>> Jake
>