Delfield freezer

[supercooljim]

Basically what's happening is unit runs nd starts fine.I can here it pump down then shuts off comp.Whem it cycles back on the comp tries to start,hums and trips breaker.I have even unplugged it before it trips breaker.If I plug it back in wright away it will still hum.After 30sec.to a minute it will start wright up as normal.I replaced the start cap and pot relay with Copeland OEM components.I have substituted this freezer with another one so I took the Delfield into the shop plugged it in and same thing happens....readings are as fallows when in operation....Low side 15psig high side 200psig,RLA is 11amps,LRA @start up is 57. voltage through out is 115v...breaker is a 30amp...

[timebuilder]

Basically what's happening is unit runs nd starts fine.I can here it pump down then shuts off comp.Whem it cycles back on the comp tries to start,hums and trips breaker.I have even unplugged it before it trips breaker.If I plug it back in wright away it will still hum.After 30sec.to a minute it will start wright up as normal.I replaced the start cap and pot relay with Copeland OEM components.I have substituted this freezer with another one so I took the Delfield into the shop plugged it in and same thing happens....readings are as fallows when in operation....Low side 15psig high side 200psig,RLA is 11amps,LRA @start up is 57. voltage through out is 115v...breaker is a 30amp...

I highlighted the text in big letters above, because I think the answers are staring you in the face. What changes while the unit is not running?

When it trips the breaker, it has several minutes to equalize the pressures. That's my bet.

Did you take the pressure readings that I indicated? THAT will tell you why it won't run, and draws LRA.

Here's the task list:

1) Record the pressures when the unit is failing to start. What's the head?

2) Ask yourself: is the charge correct? Have you pulled the charge and charged to the exact oz value? I have learned that you CANNOT trust the charge to be correct. In fact, you cannot assume the refrigerant is correct, either. You are not the first guy to work on this system.

3) When running, what is the suction pressure and the superheat? If the unit was satisfied a few minutes ago, it is no longer a hot pull down scenario, so you should have acceptably low superheat.

4) If this is in a kitchen, is the condenser really clean?

What say you all, guys? Anything to add?

[Tommy knocker]

I highlighted the text in big letters above, because I think the answers are staring you in the face. What changes while the unit is not running?

When it trips the breaker, it has several minutes to equalize the pressures. That's my bet.

Did you take the pressure readings that I indicated? THAT will tell you why it won't run, and draws LRA.

Here's the task list:

1) Record the pressures when the unit is failing to start. What's the head?

2) Ask yourself: is the charge correct? Have you pulled the charge and charged to the exact oz value? I have learned that you CANNOT trust the charge to be correct. In fact, you cannot assume the refrigerant is correct, either. You are not the first guy to work on this system.

3) When running, what is the suction pressure and the superheat? If the unit was satisfied a few minutes ago, it is no longer a hot pull down scenario, so you should have acceptably low superheat.

4) If this is in a kitchen, is the condenser really clean?

What say you all, guys? Anything to add?

I understand your thought process. However I don't think the pressures could equalize as you suggest. Since it is a pump down set up and the pressure switch did start and stop the comp I would have to think that if a valve was bleeding through it would continuously cycle the the comp based on the pressure rise and fall. Charge may be an issue but the locking up of comp I would suspect either a bad start relay or comp on its death bed.

[pyramidhvacr]

system low on charge. And restart back up too quickly. Supper heat to high to cool the compressor down. Raise head psi to 265. (R404A) supper heat will be close to 20-30deg / under 20deg at compress your floading it. How is it pumping down not at temp. ? Never use a 30 amp breaker on a 20 amp system. Or #12 wire.

[Tommy knocker]

system low on charge. And restart back up too quickly. Supper heat to high to cool the compressor down. Raise head psi to 265. (R404A) supper heat will be close to 20-30deg / under 20deg at compress your floading it. How is it pumping down not at temp. ? Never use a 30 amp breaker on a 20 amp system. Or #12 wire.

It ran 15-20 min made set point, pumped down and shut off. Stayed off 5 min then attempted to start and locked up. I am assuming it made set point since it pumped down, could have been a defrost if it has it I suppose but a 5 min off cycle seems reasonable to me. If charge was low enough to cause comp to overheat I would think it would be too low to make set point. Agin could have gone into defrost, if it has it, and not made set point he didn't specify that.

[timebuilder]

I understand your thought process. However I don't think the pressures could equalize as you suggest. Since it is a pump down set up and the pressure switch did start and stop the comp I would have to think that if a valve was bleeding through it would continuously cycle the the comp based on the pressure rise and fall. Charge may be an issue but the locking up of comp I would suspect either a bad start relay or comp on its death bed.

Maybe it is a pump down system, but ALL of the Delfield freezers I have worked on (restaurant reach-ins) and not pump down.

I think we need model and serial number.

[timebuilder]

system low on charge. And restart back up too quickly. Supper heat to high to cool the compressor down. Raise head psi to 265. (R404A) supper heat will be close to 20-30deg / under 20deg at compress your floading it. How is it pumping down not at temp. ? Never use a 30 amp breaker on a 20 amp system. Or #12 wire.

I'm thinking that we don't have accurate or complete info.

The OP said the unit satisfies, then can't re-start. That's why I want pressures when it fails, and personally, if I was the tech, I'd have already pulled the charge and weighed in fresh, known ID refrigerant.

[timebuilder]

Let's get that model and serial number.

[2sac]

Delfield utilizes the pump down design quite a bit in their custom applications, as well as their systems with multiple circuits. From my experience, freezers, if not controlled by a t-stat, will cycle temp from a LPC

[timebuilder]

Delfield utilizes the pump down design quite a bit in their custom applications, as well as their systems with multiple circuits. From my experience, freezers, if not controlled by a t-stat, will cycle temp from a LPC

I would agree, in general.

We have a LOT of their custom stuff, most the F18 series pizza prep tables. They use a LL solenoid to control the rail, but none that I have in the stores utilize a pump-down.

The $600 board he mentioned says to me that this is a non-pump-down reach-in. The board has several sensors with modular type connections, and it is a demand defrost configuration. Those units that I have seen with the board I described are not pump down units.

[76olds]

Question. I know the start components were changed. Were the windings ever ohmed out and have the wire connections in the compressor terminal box checked to see if they were burnt up/loose (including the nuts for the terminal board)?

[Capz]

Question. I know the start components were changed. Were the windings ever ohmed out and have the wire connections in the compressor terminal box checked to see if they were burnt up/loose (including the nuts for the terminal board)?

This is the first thing I'd check. In fact, I'd take the extra few minutes and compare resistance readings between windings after she warms up in between cycles. For me, one of 3 issues here, the compressor is under too great a load, weak wire connections somewhere in the circuit or a motor close to failure. You should be able to rule out the first two in 30 mins.

[timebuilder]

I'm hoping the OP can give us the additional info today. A model and serial number will help.

I also take my digital camera and snap a pic of the wiring diagram for the home PC.