Delfield freezer

[supercooljim]

I have a Delfield freezer I'm working on.Its a 404A system.When I got to the call I found a tripped breaker.I reset the breaker and it started no problem.I proceeded to take my pressures and temps.I had a suction pressure of 15psig witch is ok.After about 15-20 minutes I can hear it pull down then shut off.It stays off for about five minutes then when it goes to start compressor hums and trips breaker.I thought I had a starting issue so I mF the caps.All in normal range.So I added a hard start and same thing happened.Everytime I set the breaker it starts fine,then does the same thing again.Any information to guide me in the wright direction would help

[Tommy knocker]

Is this a reach in freezer? You said it pumped down. Is it supposed too? Is there a LLS valve?

[supercooljim]

Yes it has LLS valve...it's a three door commercial freezer

[supercooljim]

I'm thinking it might be the valve cause after a short time the compressor (semi hermetic) starts with no problem.Then pulls down shuts off then when I goes to start hums a trips breaker.It also has a low pressure control on it.maybe valve not opening all the way?

[Tommy knocker]

Ok alittle clearer now. If your start components check good, caps and relay, and it's humming I'd say comp is dying most likely.

[2sac]

What's the voltage at the compressor at start up? Does it drop when there's a load on it? If not, ohm out the pump. If it ohm's out ok, change the start components first before you condemn the pump.

[Tommy knocker]

If your caps checked good I wood change the relay before condemning comp as well.

[zxcb]

What's the amp draw when it's running and when it tries to start?

[carmon]

and whats the breaker size....

[vzenuh]

had something similiar happen on a true freezer. Start components bad. Replaced with oem. Installed and everything was fine while I was there. The head of maintance had left before I could fill out my invoice. Went back the next day to get a sig and the freezer was out again.

Found that voltage was fine without a load 119V. Underload 108V. Starting voltage 76V. Called true and was informed that starting voltage needs a be a minimum of 105V.

It was a 50/50 shot. If she started it was good to go, but the minute it failed to start it would cycle on internal overload over and over again.

If your voltage, start components, and amp draw prove to be good it may be something with the breaker. Poor connection? Weak breaker?

[2sac]

Exactly what I was saying.

[timebuilder]

It very well could be a low voltage issue.

You said it starts and pumps down, sometimes. Are the pressures equalized, or nearly so, when the unit tries to start at cut-in temp? If you are starting under a high load, such as that caused by a lot of head, you may need to dig deeper.

[supercooljim]

I want to thank all of you for your time on your input.I have considered a voltage problem and also a chance of the comp trying to start on high head pressure.I have tried it on separate circuit and separate location a ll together.Same thing happening.Prussures are within range.Suction stands @ 15psig and head is 200psig 404 system.RLA is @ 11amps and its pulling LRA of 57...The comp is. Copelnd semi hermetic and the RLA is rated at 10.9...After the unit satisfies it pumps down and shuts off s usual.Then after 5 or so minutes it tries to cycle back on and pulls LRA and trips breaker.I changed all starting components but still does the same.This system does have a LLS and a low pressure control.Im now in the process of suspecting its the $600 control board.Will see what follows.I was suspecting comp failure but what's throwing me off is how after it trips the breaker in a minutes time if you reset the breaker (20A) the unit starts like nothing runs till it satisfies then does the same thing...

[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.