If you don't have a cap on a single phase unit that is within range they won't start and that means you will see LRA. It could also need help starting and a 5-2-1 kit will help for a while or it might even require one...I know the larger climatuff compressors in heat pumps need one...

LRA isn't always an indication of a bad compressor, but it is possible and Mabey even likely...

 

X2

Is it possible a compressor could be pulling LRA but not locked up? Have there ever been instances with a start and run cap not functioning correctly? If you get a compressor over ampping could there be other possibilities?

Yes, (although drawing LRA typically does mean "Locked Rotor", you could also have a stuck closed potential relay where the start capacitor isn't dropping out or the circuit.

 

Yes, (although drawing LRA typically does mean "Locked Rotor", you could also have a stuck closed potential relay where the start capacitor isn't dropping out or the circuit.

 

Drawing LRA always means locked rotor...A psr not dropping out the cap will run normal for a second or 2, then fry the start winding or open the ip...

 

If you don't have a cap on a single phase unit that is within range they won't start and that means you will see LRA. It could also need help starting and a 5-2-1 kit will help for a while or it might even require one...I know the larger climatuff compressors in heat pumps need one.

Drawing LRA always means locked rotor...A psr not dropping out the cap will run normal for a second or 2, then fry the start winding or open the ip...

So witch post is correct? (or can they both be correct?)

Drawing LRA always means locked rotor... (mechanically stuck)

or

If you don't have a cap on a single phase unit that is within range they won't start and that means you will see LRA.... (weak run capacitor)

 

I don't think I understand the potential relay well maybe. The relay is use every time correct? Is there ever time it will potentially not be in the start up process? Is this type a relay alway a 5,2,1 relay? Also if the start cap was flat could we see the LRA or would we only see the LRA if the start cap was in countinus use?

 

What is ip? Internal protection/ overload?

 

Technically speaking ,no. Locked is locked. Now it may be mechanically locked which means a defective comp. But an electrically locked comp might be locked due to a defective component, replace the bad part and the comp might start and run.

I think a stuck closed pot relay will start draw high amps ( the comp is moving) but not for long. Then if the start cap blows or burns the start winding then you are back to a LRA.

Copeland has a 3-4 page bulletin call "Miswiring is Murder" its a very good read. And it has pictures.

 

Thanks for clarifying. Do you have a .pdf of that bulletin to share?

 

Thanks for the replays guys here is the pdf I believe

http://icemeister.net/files/compressors/copeland/Copeland Miswiring is Murder.pdf

 

If the start cap it bad and the relay is out when the call for cooking come on, we should get the LRA correct? Since no start cap the compressor will not even try to run correct? It will just sit there and heat up while displaying LRA? The term IP was used earlier in this thread, what does that term mean? Internal protection/overload?

 

If your start capacitor is faulty, what will happen is you'll see the compressor draw near LRA for 1-3 seconds, then the potential relay will drop it out. This isn't the same as a locked rotor where you draw LRA consistently until the overprotection device breaks the circuit.

 

you could ohm the compressor? remove the cap that connects wires to the compressor. put your ohm meter across the pins. c-r, c-s, r-s. Record the readings c-r+c-s= r-s. Which each pin is will be on the cap. then you can do each pin to the shell of the compressor. This will tell you if you have a bad winding or a winding short to ground. The pin to wall ratings all should be a zero or open reading.

 

Nice to have you in the discussion , airfx.

To prevent confusion, remember zero resistance is the exact opposite of an open circuit.

 

Hay, that is the Copeland Bulletin, mine is dated 1978, and I got it new.

 

If you are pulling constant LRA could that just mean the start cap didn't get the compressor going? Could we be seeing LRA with the compressor only running with a run cap? Also is a hard start kit useful on a system that has a start and run cap? Do hard start kits only connect to the run cap?

 

If you are pulling constant LRA could that just mean the start cap didn't get the compressor going?
》Yes. Could be liquid-filled cyl, excess head pressure, washed out bearing.

Could we be seeing LRA with the compressor only running with a run cap?
》Well, if it's running, it will not be drawing LRA, will it.
If you mean trying to run, it again will be less than LRA.


Also is a hard start kit useful on a system that has a start and run cap?
》Not for operation, but a fast way to check the start components.

Do hard start kits only connect to the run cap?
》The hang-on 2 lead type...yes.

Hope this is of some help.
Sorry for the mangled quote as there's minimal edit tools with phone posting.

 

I will use some numbers.

If LRA is 87 amps and on the data plate of the unit it says comp FLA is 17.5

If the compressor is drawing 87 amps it locked...if it's drawing 55 amps it's still locked...22 amps and running obviously means there is something that could be wrong or a high load, but starting isn't where I would start...

I meant by the > sign that you will have a decent amount over FLA up to RLA and it's still the same thing locked rotor...

 

In answer to the OP, I have seen defective compressors with good starting components drawing very high amps, consequentially tripping on the internal overload after running for a few seconds.