[iceburg]

What is is with the Ranco constant cut in controls? Why do they say on the box Cut in 39*, for a A12-1560 but the paperwork says Normal off 24* Warm Off 29* Cold Off 19* Cut In 38* ??
I always thought that according to the literature, the control was set to cut in at 39 and cut out between the Cold Off(19*) and the Warm off(29*) depending on the dial setting.

I had replaced a control K12-1536 because the cut in was 43* and higher.
the customer wasn't going to store his chicken in there until the temp problem was fixed.

I replaced the control with the Ranco A12-1560 but couldn't get the thing to control as expected.

Unit Make : Victory Model: RIA-2D-s7 115V 134a

Pulled the evap blades, coil comes right down and got to 10*
The 1560 is for a straight tube, but had improvised a coil to insert in the same location as the original control.

Cut out was 25* CI 43/44*

Help Please, these controls are frustrating, but I'm sure someone will help me make sense of them.

Any helpful tips on what controls to stock for different applications. (ie Cap Tube, TXV, Reach ins, Refrig, Freezer, etc.)I've kept the 1506's, and the 1560's on the truck.
Thank You!!

 

[UmmScott]

A12 700....boom

Perfect for reach ins...that's all we use

 

[iceburg]

Are they coiled at the end, or a straight cap tube you insert thru a tube from the side of the coil? And whats your take on explaining the Normal off, Warm off, Cold off?

 

[BBeerme]

The A12-1560 is a wonderful little control. Most uses are for small refrigeration, but I've even put them on problem walk-in's and have had great success. The key to taking the frustration out of the equation is understanding their use and application.

Their use:
Virtually any small refrigeration. Or any application where evaps freezing up is a common occurrence.

Their application:
Understanding the constant cut in is important. That constant cut in means you are guaranteed a defrost and clean evap before the compressor starts again. So how to mount it? You need to bury the capillary tube deep into the fins of the evap, that's how you make it work. It's pretty simple in practice, but maybe hard to explain. Remember, you need to get a bunch of that capillary tubing into the coils to sense that temp [you do not need a tube mounted from the manufacturer to put that capillary into].

 

[iceburg]

Thanks for that. I pretty much get the purpose and do appreciate your response. I'm looking for a more technical approach to understanding exactly what they mean by the (3) off settings. Is it ok to take a 1560 and coil the end, and are there particular controls for certain specific applications? Like TXV vs. cap tube. There are a whole slu of cut in controls, how should one select the proper control for what he's working on.

 

[BBeerme]

Thanks for that. I pretty much get the purpose and do appreciate your response. I'm looking for a more technical approach to understanding exactly what they mean by the (3) off settings. Is it ok to take a 1560 and coil the end, and are there particular controls for certain specific applications? Like TXV vs. cap tube. There are a whole slu of cut in controls, how should one select the proper control for what he's working on.

Do not make it any more complicated than it really is.

Sure, coil the end if you want. Just be sure to bury it in the coil. The stat will then only sense the spot you put that coiled bulb.

 

[UmmScott]

They're coil sensing...no metering device doesn't affect them usually if they're feeding correctly.
Remember reach ins have a 15°F temp difference...so if u want to average a 35F box then ur coil is gonna have to pull down to 18 or so..and the stat will cut out depending on what # its set on
A12700 cuts in at 37...great for beer, pop, and other beverages
A12701 cuts in at 41 more so for food coolers.

 

[Mike19]

Why do they say on the box Cut in 39*, for a A12-1560 but the paperwork says Normal off 24* Warm Off 29* Cold Off 19* Cut In 38* ??
I always thought that according to the literature, the control was set to cut in at 39 and cut out between the Cold Off(19*) and the Warm off(29*) depending on the dial setting.

Yeah.

When the temperature is set at its warmest setting it will cut-out at 29 and cut back in at 39

When its set at the middle setting it will cut-out at 24 and cut back in at 39.

When its set at the coldest setting it will cut-out at 19 and cut back in at 39.

Personally, I prefer the a12-700, I use it for pretty much all coil-sensing medium temp applications.

 

[Snapperhead]

You also need to check pressures if you can. If its low on refrigerant it wont pull down well.... and it short cycles. Likewise if overcharged, it wont pull down well.

 

[Snapperhead]

Whats the diff between a 1560 and 700 ?

 

[iceburg]

why this control over the others. Is it because it's more universal due to it lower cut out temp?

 

[Mike19]

why this control over the others. Is it because it's more universal due to it lower cut out temp?

Yes, because of the lower cut-out.

 

[Chillin1981]

In a nut shell the constant cut in t-stat is used so manufactures do not have to add a time clock to defrost the coil. The end of the cap tube is installed or buried in the evap coil so once the control has turned the unit off it will not restart until the evap reaches 39 degrees to insure there is no frost left on the coil. I agree with using the 700 to replace it with as it gives you a wider operating range. The major limitation of the control is its lock rotor ratings cannot handle a larger H.P. Compressor. The controls work well for small door refrigerators with up to 1/3 hp compressors.

 

[2sac]

They're coil sensing...no metering device doesn't affect them usually if they're feeding correctly.
Remember reach ins have a 15°F temp difference...so if u want to average a 35F box then ur coil is gonna have to pull down to 18 or so..and the stat will cut out depending on what # its set on
A12700 cuts in at 37...great for beer, pop, and other beverages
A12701 cuts in at 41 more so for food coolers.

This is important. An incorrect charge or restricted metering device may not be blatantly obvious when you have no refrigerant ports to connect your gauges to. Bad thermostats is a common misdiagnosis

 

[UmmScott]

This is important

Right...I imagine...a partial restricted cap tube.. Or an underfeeding txv will cause it to cut out too soon

 

[UmmScott]

Err well I guess it's a balance anyway...maybe a small enough restriction would cause it to cut out too soon due to the lower coil temp....but more restricted it may not cut out at all.

I had a standard true t23 cooler kept freezing up and would maintain 38 degrees but never shut off.

When I tapped on I had 10 suction, 125 head with a clear coil. Drier ended up being plugged. Afterwards had normal pressures and proper stat operation

Point here is that anyone could've easily diagnosed the stat as sticking when it really was a refrigeration issue

 

[ECtofix]

This is important. An incorrect charge or restricted metering device may not be blatantly obvious when you have no refrigerant ports to connect your gauges to. Bad thermostats is a common misdiagnosis

Yup. Done that and learned from it.

Right...I imagine...a partial restricted cap tube.. Or an underfeeding txv will cause it to cut out too soon

...or not cut out soon enough.

If only part of the evap coil is cooling due to a clogged cap or a low charge, but the stat's sensor is located further along and therefore affected by refrigerant already well into the superheated range, the stat may not satisfy until the box is below freezing.

Had a few do that and was freezing their veggies.

 

[iceburg]

The major limitation of the control is its lock rotor ratings cannot handle a larger H.P. Compressor. The controls work well for small door refrigerators with up to 1/3 hp compressors.

Ive used them in a pinch when the walk in box was using pump down with a LPC.