Commercial refrigerator stops cooling after a few hours...

[fridgetech ay]

This is my first time commenting on anything here so be gentle.
I may be wrong but the photo of the t'stat looks like it is outside the refrigerated space, if not sorry, the A19BBC-2 has three terminals. C-NO-NC, a simple check to ground on any one will confirm voltage and which way t'stat is switched.
17 oz of refrigerant sounds to me like a reach in unit maybe two door.
Probably not much for safeties in circuit.
If you have not checked pressures and subcooling and superheat yet, don't call for help untill you do.
Good luck...

[jackintheboxtec]

Replace the stat!

[MicahWes]

Whether that control is bad or not, you definitely need to replace it with the proper constant cut-in control. The sensing element probably needs to be buried in the evaporator.

[top shelf]

Tripping on O/L ? Just a thought.

[2sac]

That's a true cooler and it is the incorrect thermostat. That type of thermostat is usually mounted on the back wall of a wic. I don't care for those stats and usually replace them. The correct thermostat should be installed. The sensor slides in a copper tube which is attached to the coil. Before you replace the stat you should check that everything else is working properly.

[kamersoutdoor]

That's a true cooler and it is the incorrect thermostat. That type of thermostat is usually mounted on the back wall of a wic. I don't care for those stats and usually replace them. The correct thermostat should be installed. The sensor slides in a copper tube which is attached to the coil. Before you replace the stat you should check that everything else is working properly.

Is there any literature on this? Knowledge is power, and am often confronted when suggesting to change these to a constant cut-in.
I'm guessing that constant cut-in will also help with liquid migration (frozen coil)???

sent from my Samsung Galaxy Note

[kamersoutdoor]

To clarify, confrontation has come "more often than not", from fellow techs rather than customers!

sent from my Samsung Galaxy Note

[2sac]

Literature on???
The OEM control for true is a constant cut in and is designed to fit in the copper tube. I have used non oem constant cut in controls on some of the True's where either the copper tube has come loose or the cap tube on the oem controller has broke off inside the tube. Coiled up the cap tube and inserted in the coil That type of control allows for an off cycle defrost. The style of control that is pictured, in my experience, has always been mounted on the back wall or back side of coil of a wic It needs to be in the return air stream. Personal preference, I do not like those controls.

[2sac]

In the OP's pic, ithe cooler is designed to draw air thru the fan and over the coil. If the box is full the supply air will circulate around the coil thus the control is sensing supply air and is why it it cycling improperly.

[koolkahuna]

I had a True prep table that gave nothing but grief with the OEM cold controls failing after 2-3 months. This customer was 2 hours away so it really sucked. I went through 3 original controls before I realized they were definitely failing due to poor quality.

After asking around I found out my situation was not unique. I now use a Danfoss KPU73 instead of the original OEM constant cut-in cold control. I insert the bulb in the middle of the coil about 6" down from the top. I work the fins apart gently with a plastic pen until the coil just slides in with a little resistance.
No more problems and it's been 8 months!

[kamersoutdoor]

Constant cut-in (??-40deg) set cut-in helps defrost coil, by lowering the stat you depict the differential?
I set cntrl to let's say seven, I bring unit to 31° and contacts open, if constant is 39deg then contacts remain open until set point is reached allowing defrost compared to air sensing stat?


sent from my Samsung Galaxy Note

[2sac]

True had some bad controls getting shipped out for awhile. The biggest issue with Trues and their t-stats is improper diagnosis by techs. The first thing to get changed out if a unit is low on charge or a partial restriction it the t-stat because all the signs point to an erratic control. Guys blame the stats going bad when in fact the diagnosis was incorrect. In no way I am insinuating this is what's happening in your case.

You've had success with the danfoss? I'll have my shop look into them.

[koolkahuna]

True had some bad controls getting shipped out for awhile. The biggest issue with Trues and their t-stats is improper diagnosis by techs. The first thing to get changed out if a unit is low on charge or a partial restriction it the t-stat because all the signs point to an erratic control. Guys blame the stats going bad when in fact the diagnosis was incorrect. In no way I am insinuating this is what's happening in your case.

You've had success with the danfoss? I'll have my shop look into them.

Did you mean partial restriction in the tstat or the cap tube?