Help with another "Goodwill" call...

Posted by Jake on July 10, 2006, 8:15 pm

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.

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

Posted by on July 10, 2006, 9:14 pm

wrote:

>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.

and the compressor wasnt too damned hot to touch??
Now there's a first..............

>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.
>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?

turn power off for 24 hours. connect a TO-5 hardstart kit to Start &
Run terminals and turn on the power & mash in the contactor. If it
starts up, pull the oem potential relay and run cap and install new
oem parts. If it doesnt start up, warm up your compressor changing
tools.

>Jake

Posted by Fat Eddy on July 10, 2006, 9:15 pm

Jake wrote:

Still missing a reading here, ( and these sound low ) in general the
two lowest will add up to the highest, ( approx )

> 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.
> 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.

Nothing here says that it is not trying to start, you can not tell by
listening, that is no way to verify current draw.

> 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.

They probably do not work that fast, but could.

> 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.

If the start winding is damaged the I/O can trip pretty quickly,

> Any suggestions?

Jake,

We need to go back to fundamentals here, get all three winding
resistances, verify that the cap is ok, Try to start the unit with an
amp clamp on the circuit and set it to save the max reading, then if it
does not start, shut the power down and read the winding resistances
again ( quickly), if they are now open then you know that it did pop
the I/O.And if your start components are working properly then you have
a bad compressor because of a defective overload or a locked rotor, but
you need to know what it is doing as it tries to start, thats the key
here I think.

Fat Eddy
www.hvactalkforum.com

Posted by Stormin Mormon on July 10, 2006, 9:42 pm

As Fish says, the hard start kit is worth trying. I'd also want to
check the cap for short / open.

Most of the time when I encounter a bad compressor, at least you can
hear it TRY to start. Or, it trips the breaker right off. That's a
really odd combination of events.

Might want to check the voltage at the compressor while it's doing all
this. You could have a dirty connection, and the voltage is dropping
way down during the "trying to start" times.

Please let us know what you find.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
.

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.

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

Posted by HeatMan on July 11, 2006, 7:55 am

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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