Commercial Refrigerator will not switch to run winding

[Dima]

I have very old commercial refrigerator Beverage-Air RF49-1AB which had bad starter capacitor and would pull about 50 Amps and not able to get going.  I replaced starter capacitor with identical one and now it does spin up but will not switch over to run winding and still pulls roughly 50 Amps.  I suspected a bad relay (original relay GE 040-0001-51) so I bought equivalent (part actually says 040-0166-11 but order said same as original); relay coil reading is identical to the original 3.6K.  After replacing relay I get same results - compressor is rotating and runs pretty rough (believe because it is running on start winding which is slow).  If I unplug start winding from relay, compressor speeds up and runs just fine and drops to 11 Amps.  Going off my memory: Start winding around 2.5 to 4 Ohms, Run winding around 12 Ohms, none of them shorted to the case; has run and start compressor, run capacitor measures just what label says and if I unplug run capacitor once compressor is running fine current draw goes up to around 16 Amps which suggests it does what it suppose to. 

So I am puzzled as to what is the issue with it.  Attached is the schematic but ran into trouble attaching other pictures I have of compressor connection and other things.

[Shira]

Are you sure that's the right model number? This is what comes up when I google search it... Amazon.com: Beverage-Air Model RF49-1AS Magnetic Door Gasket : Industrial & Scientific 
Or maybe this? HBRF49-1-AB.pdf (beverage-air.com)

Also can't see any attachments so maybe try that again.

[Terry Carmen]

Something is way off. The unit is only supposed to use a little over 11 amps to start and a little over 5 to run.

 

[Dima]

22 hours ago, Shira said:

Are you sure that's the right model number? This is what comes up when I google search it... Amazon.com: Beverage-Air Model RF49-1AS Magnetic Door Gasket : Industrial & Scientific 
Or maybe this? HBRF49-1-AB.pdf (beverage-air.com)

Also can't see any attachments so maybe try that again.

You are correct, it is HBRF49 series.

14 hours ago, Terry Carmen said:

Something is way off. The unit is only supposed to use a little over 11 amps to start and a little over 5 to run.

 

So it is too high even for a commercial compressor?  This compressor is Copeland KAMB-007A-CAA-800, LRA 85.5 - it is definitely a massive compressor.  Having trouble attaching more files.

[Dima]

Here is schematic that comes with refrigerator. 

[Dima]

[Dima]

[Dima]

[Terry Carmen]

According to Copeland spec sheet for that compressor, it should be drawing a maximum of about 10A during normal operation, while the cooler manufacturer says a little over 5.

You might want to contact the cooler's manufacturer and see what's actually normal for this unit, and what start relay, capacitors and overload it's actually supposed to have, so you don't end up chasing ghosts.

https://www.meiersupply.com/customer/docs/skudocs/Document_Links/Vendors/106685 - Emerson/Compressors/K-Series/-AMB/-007E/-CAA/Components/ec.pdf

https://www.meiersupply.com/itemdetail/COPE KAMB-007E-CAA-800

Edited August 28, 2021 by Terry Carmen

[Dima]

On 8/28/2021 at 10:07 AM, Terry Carmen said:

According to Copeland spec sheet for that compressor, it should be drawing a maximum of about 10A during normal operation, while the cooler manufacturer says a little over 5.

You might want to contact the cooler's manufacturer and see what's actually normal for this unit, and what start relay, capacitors and overload it's actually supposed to have, so you don't end up chasing ghosts.

https://www.meiersupply.com/customer/docs/skudocs/Document_Links/Vendors/106685 - Emerson/Compressors/K-Series/-AMB/-007E/-CAA/Components/ec.pdf

https://www.meiersupply.com/itemdetail/COPE KAMB-007E-CAA-800

Appreciate info. 

The original start capacitor was shot, it was measuring in under 1uF where it should have been over 430uF, so I was hopeful it was going to be the end solution.  After it hasn't been resolved and disconnecting Start winding got compressor to run normally - I assumed it was relay; unfortunately after relay replacement results didn't change. 

Can it be a bad run capacitor or is it something internally wrong with compressor you think?  

I was under impression that current draw going through relay is what causes it to activate and switch to Run winding, is it not the case? If that is the case should I suspect compressor somehow gets power that is not going through relay winding? Can it be a run capacitor is faulty?

[Terry Carmen]

7 minutes ago, Dima said:

I was under impression that current draw going through relay is what causes it to activate and switch to Run winding, is it not the case? If that is the case should I suspect compressor somehow gets power that is not going through relay winding? Can it be a run capacitor is faulty?

I'm not sure what this unit actually uses, but if it's an actual "start relay", the current through the run windings energises the start winding. Once the motor comes up to speed and the run winding current drops off to normal, the start winding is de-energized. 

Yes, the run capacitor can be bad.

Since this is acting weird, at this point, I'd replace both start and run capacitors and the start relay with the OEM specified parts. 

Edited August 30, 2021 by Terry Carmen

[Dima]

On 8/29/2021 at 10:17 PM, Terry Carmen said:

I'm not sure what this unit actually uses, but if it's an actual "start relay", the current through the run windings energises the start winding. Once the motor comes up to speed and the run winding current drops off to normal, the start winding is de-energized. 

Yes, the run capacitor can be bad.

Since this is acting weird, at this point, I'd replace both start and run capacitors and the start relay with the OEM specified parts. 

Ok, will give it a shot.  At this point Run capacitor is the only part that wasn't replaced.  I will give it a shot and if doesn't work will assume issue with compressor.  Thank you for the help!

[Terry Carmen]

If possible, you might want to check the pressures.

Some commercial units have a valve that unloads pressure from the high side when the unit stops, to make startup easier (or possible). If the valve isn't working, it's difficult for the unit to start.

[Dima]

8 hours ago, Terry Carmen said:

If possible, you might want to check the pressures.

Some commercial units have a valve that unloads pressure from the high side when the unit stops, to make startup easier (or possible). If the valve isn't working, it's difficult for the unit to start.

I wonder if it is marked on schematic as High Pressure Output on bottom.  I did see some sort of electrical component on refrigeration line close to compressor with 2 wires leading to it - wonder if it's what you are referring to.  If it is the case I have no experience with sealed system - at this point it is the only thing I stay away from in appliance repair.

[Terry Carmen]

1 hour ago, Dima said:

I wonder if it is marked on schematic as High Pressure Output on bottom. 

That's "High Pressure Cutout" and kills the compressor if the high side pressure gets too high.

There are also mechanical versions, but it's also possible it doesn't have or need one one at all.

 

[WOOKIE]

Compressor windings.  when measuring the resistance. The run windings is a smaller resistance than the start winding.

example:  measuring common to run 4 ohms

                  measuring common to start 8 ohms

                  measuring run to start 12 ohms. (the higher ohms) 

at startup ,the start relay brings  in the start winding long enough to get the rotor turning .  When it reaches a designated current draw ( Based on the relay) the Start Relay  removes the start winding from the circuit. 

What you have is one of two things.  the start relay is bad and, not removing the start winding from the circuit. The other case is the start and run winding are shorted together. 

[Terry Carmen]

Nothing useful to add, except "Please let us know what happens". I haven't done commercial work since the 1990's but it's interesting.

[Dima]

On 9/4/2021 at 8:31 AM, WOOKIE said:

Compressor windings.  when measuring the resistance. The run windings is a smaller resistance than the start winding.

example:  measuring common to run 4 ohms

                  measuring common to start 8 ohms

                  measuring run to start 12 ohms. (the higher ohms) 

at startup ,the start relay brings  in the start winding long enough to get the rotor turning .  When it reaches a designated current draw ( Based on the relay) the Start Relay  removes the start winding from the circuit. 

What you have is one of two things.  the start relay is bad and, not removing the start winding from the circuit. The other case is the start and run winding are shorted together. 

I do not recall it vividly anymore but I believe sum of both windings added up and know for a fact none were shorted to the chassis.  Start relay was replaced with exact equivalent with exact same results, in fact new and old relays windings measure exactly the same - must be that the old relay is ok after all.

On 9/4/2021 at 10:37 AM, Terry Carmen said:

Nothing useful to add, except "Please let us know what happens". I haven't done commercial work since the 1990's but it's interesting.

Explained situation to the client, will see if he will want me to proceed with last component replacement test.  

[WOOKIE]

35 minutes ago, Dima said:

I do not recall it vividly anymore but I believe sum of both windings added up and know for a fact none were shorted to the chassis.

If any winding was shorted to chassis  (allowing for proper grounding back to the CKT breaker) the CKT breaker would trip. When you remove the start winding from the circuit the compressor smooths out and, speeds up.  I would suspect that  the start winding is shorting to the run winding adding resistance when running.  Or, the start relay is not wired correctly leaving the start winding in the circuit.  Also with some potential relay's the are position specific. Meaning some have a statement on them "this side up" or it will not drop the start winding out. 

I will study the picture's later to check the wiring on the potential relay

[Terry Carmen]

2 hours ago, Dima said:

Explained situation to the client, will see if he will want me to proceed with last component replacement test.  

They're apparently about $8000+ new and probably not available right now, so I'm guessing if you wanted to bring in an Exorcist, he'd probably be OK with it.

[Dima]

Wanted to follow up and thank everyone participating in troubleshooting this one. 

I ended up making my last trip out to get full picture of what is going on.  Took all the measurements I could think off after turning it on with new Run capacitor, Start capacitor, relay.  Results are exactly the same as what I was getting with only Start cap replaced. 

I ended up using TEMCo run capacitor https://temcoindustrial.com/ac-electric-motor-run-capacitor-rc0013-40-uf-mfd-370-vac-round-hvac/ thinking it is lost cause and even though it is same spec, I wonder if there is more to it that I might not know yet.

Relay I used is 040-0166-11 and it is listed on manufacturer's spec is one of the exact replacement for relay, on top of that coil reads exactly as original.  But I wonder how is that relay suppose to switch from Start to Run winding with coil being 3.6K - nothing will flow through it having only few ohm Start winding.  I have tried experimenting with relay applying 120V directly to coil but it will not engage no matter how long I waited.  But if I start quickly applying and removing supply to it - it does engage and stays engaged. Wonder if it suppose to work with capacitor in some way. 

https://www.meiersupply.com/customer/docs/skudocs/Document_Links/Vendors/106685 - Emerson/Compressors/K-Series/-AMB/-007E/-CAA/Components/ec.pdf

At the time I concluded that winding inside compressor must have shorted, being in only few ohms.  But now I am second-guessing myself.  Spec sheet says "Start Wdg: 2.25; Run Wdg: 0.40" which is pretty much what I measured on compressor and no short to case.  

Just trying to understand the culprit here.  Any thoughts are appreciated.