Deli Case - not behaving

[HoneyDo]

Customer asked me to look at why his deli case is making loud buzzing noise.
It is a McCray case SCCDS35-4 s/n 94-47831-7.

I have not put gauges on yet. Sight glass is full and green.
It sounds like a loud buzzing noise coming form the compressor.

I suspect either the relay, overload or capacitor.

I plan to front seat the high side on the receiver, pump down to look for vacuum. Check amp draw.

Any other suggestions?

[dirtyboy103us]

how about a contactor or relay

[icemeister]

That current case model uses a 1/4 HP CopeVap condensing unit, so there wouldn't be a contactor. It should have a discharge gas loop in the unit base which often creates an annoying buzzing noise.

I've also had similar sounds generated by the start capacitor if it's not secured tight in its mounting bracket. Then of course it could be the fan shroud vibrating.

[76olds]

Stop condenser fan motor from running, see what happens. Could be as simple as fan blade hitting something or something not screwed on tight.

[monkeyspanners]

Sometimes the rubber mounting feet perrish and allow a comp to bottom out on the chassis, making a noise.

[HoneyDo]

The cap and relay were badly overheated the cap wires were so brittle the insulate crumbled. The overload connections to cap were also badly rusted/corroded.

Changed Cap and Overload.
Noise level came down but still not as quiet as I would expect.

Icemeister mentioned that...
"should have a discharge gas loop in the unit base which often creates an annoying buzzing noise."

Any way to remedy this??

And thank you for all your information, it helps me organize my thoughts when it comes time to explain what might be wrong.

[icemeister]

...Icemeister mentioned that...
"should have a discharge gas loop in the unit base which often creates an annoying buzzing noise."

Any way to remedy this??

I usually start by grabbing different sections of the piping to see if the noise stops. (You may want to wear some good gloves while doing this around the discharge lines. )

Often, all it takes is "a somewhat less than scientific bend of the tubing" here and there to eliminate the problem.

[HoneyDo]

I searched for the noise maker and blame the compressor.
Disconnected the pot and let the condenser fan run on it's own. No Problem.

I'm beginning to think that I should have thrown some
gauges on and add an oz. of 134a

I'm gonna go back today and see what else I can discover.
I'll also try to front seat the receiver and look for suction.

[HoneyDo]

Added 10 oz., same buzzing.

Front seated the high side waited and waited a few minutes and no vacuum.
The buzzing has got to be a valve or something, because of no vacuum right?
I'm gonna price a new compressor for Monday.

[IceVicious]

BALLEST ????

[HoneyDo]

Ballast?

What do you mean?

Funny because the sound IS like a bad light ballast. But louder.

I turned the light off with the compressor running. Same problem.

[76olds]

tecumseh compressor?

[HoneyDo]

Copeland,

Do you think there is something I may be overlooking?

The noise it makes sounds like the straining buzz you get from
a compressor that just starts up, then in seconds
the noise normally subsides.

But this pot just buzzes and buzzes.

There is a separate switch to turn the lights off inside the case.
So I doubt it can be a ballast.

After back seating the receiver valve the low side gauge just sat at about 25lb. and the high side was at about 100lb. and the temp wouldn't go above 48˚.

[76olds]

Tecumseh compressors can get real loud, that's why I asked. You frontseated the receiver service valve and it only pumped down to 25#, you need a compressor. I'm just curious as to what this compressor sounds like, thats all.

[mmmdave]

What indicated the need to add refrigerant?

You said cap and relay were overheated, and you replaced cap and overload. Did you replace relay? Bad relays are known to buzz.

[HoneyDo]

The buzz sounds like, 'when a manitowoc goes into a harvest cycle' but louder.

Replaced cap and relay, same buzz.

Relays do buzz, and thought to go with least expensive parts before I get to far into a bad compressor.

Maybe the new relay was a defect.
As an after thought, I guess I could have thrown on a hard start combo to test that out?

I added 134a hoping to see if the noise would improve.
Just as an experiment.

I just quoted a pot replacement. I'll see if he goes for it.

It seems that for the price of the pot and 4-5 hrs. time,
he's considering replacing with another unit. His call.

[maxpower]

Maybee there's a big Bee stuck in there somewhere?