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For years I found time clock defrost when the clock tells it to go into defrost. Sometimes when it's not needed or not enough times. Low pressure controller goes into off cycle when the coil needs to defrost if it's set right.

I also just read all the threads and did not realize it was started in 2005!
A lot has happened with electronic control systems since then and there are now controls out there that combine all the functions needed on an evaporator,including fan control, thermostat, defrost termination, fan delay, drip time, door switches and other alarming functions plus internet communications.
Best of all demand defrost algorithms that finally work!

Originally Posted by baub

The A12-1506 has a pig tail for coil insertion or air sensing. Also a shorter cap.

Thanks baub,
Might work better on reach-ins with no capillary well.Usually on a A12-700 I will fold the cap tube over a few times if there is no well and place it between the fins.

Originally Posted by vzenuh

Not to change the subject, but we recently got called back to a new customer. Freezer never getting below zero. Excessive water drops on top of walk in freezer. Head manager is a stickler for always closing doors and correcting employees when the door is left open for whatever reason. Walk in freezer, walk in cooler, close the damn door.

I went out there and saw with my own peepers one of the main problems. Delivery truck had come in. Product left in kitchen. Employee has door wide open for about thirty minutes. I finish my work on the reach in cooler and go over to the freezer. It's not at temp and water drops on the ceiling. I grab the only manager I can see and point out to her that the door can't be left open for an extended time like that and this is the result. Showed her the drops on the ceiling and the coil that was excessively frosted up.


I learned that employees that make minimum wage dont give a hoot about closing the door to the freezer. it's cold in there.

Here is a good one, can't believe I am going to admit this......................... but, when I was in High school I worked at a mini mart convenience store. The air condition use to break all the time, so I would open up freezer and cooler doors to cool of store.

The A12-1506 has a pig tail for coil insertion or air sensing. Also a shorter cap.

Originally Posted by timebuilder

Here is a Ranco page that shows how the controls compare for temperature range.

http://www.uni-line.com/images/docs/...erence-pg3.jpg

Looks like jp's A12-1506 only varies slightly from the A12-700 by a few degrees cut-in. Does it do anything special ?

Originally Posted by VTP99

Wow !! 2005 how is it that these old post get revived ? I never even looked at the date. on the Ranco A12-701. I'll have to check out the Ranco A12-1506 that timebuilder mentioned.

Here is a Ranco page that shows how the controls compare for temperature range.

http://www.uni-line.com/images/docs/...erence-pg3.jpg

Originally Posted by smurphy

I started reading this thread this morning till I got to my original posts. Then I realized this was from 2005, LOL. Anyways, I actually quit using this setup. I don't know why. Maybe at the time I was working for someone, and now I'm a owner. I do remember I had good results at the time. Mostly used it on walk in beer coolers. Nowadays, I just add a defrost timer, four defrosts a day, air defrost for 45 minutes.

I use the Ranco A12-701 (constant cut in @41) for reach in coolers.

Wow !! 2005 how is it that these old post get revived ? I never even looked at the date. on the Ranco A12-701. I'll have to check out the Ranco A12-1506 that timebuilder mentioned.

Double post

Originally Posted by VTP99

I don't believe the johnson a19abc-24c is a constant cut-in control (your post #15) Correct me if I'm wrong. Now a Ranco a12-700 would be.

I started reading this thread this morning till I got to my original posts. Then I realized this was from 2005, LOL. Anyways, I actually quit using this setup. I don't know why. Maybe at the time I was working for someone, and now I'm a owner. I do remember I had good results at the time. Mostly used it on walk in beer coolers. Nowadays, I just add a defrost timer, four defrosts a day, air defrost for 45 minutes.

I use the Ranco A12-701 (constant cut in @41) for reach in coolers.

JP turned me on to the Ranco A12-1506. It has worked very well on two occasions where there was a control failure.

Originally Posted by smurphy

I use a constsant cut in t-stat on walk in coolers all the time.Been able to maintain a 34 degree box temp with out any icing problems.

I don't believe the johnson a19abc-24c is a constant cut-in control (your post #15) Correct me if I'm wrong. Now a Ranco a12-700 would be.

Originally Posted by gas_n_go

Did not read through entire thread so my apologies if this has been covered. I always prefer controlling temp with a lpc for a few reasons.

1. Offers compressor protection
2. Kiss timeclock can't fail if it's not there
3. Customers can crank stat down but I control how low it will go
4. Saves nuisance calls from iced up coils due to door being left open or fans turned off because it's self regulated.
5. Maintains better product integrity
6. Better energy efficiency
7. Compressor life extended because it cycles better


Sidenote regarding blends

They are a bit trickier what you need to member is that they enter as a liquid and exit as a vapor and only in the center are they a true saturated state.

For example say you are looking for a co evaporation temp of 15degrees and your refrigerant has a corresponding bubble point of 10lbs and a dew point of 20lbs the correct co pressure is 15lbs.

What that does is compensates for the glide and should produce 15 degrees at the center point in your coil. It sounds more confusing then it is but it does work.

If the condensers are outside then your LPC is being used in the pump down. In my AO the cut out is set for 1lb and the cut in is about 15lbs. When it's -30 outside the LPC still has to be able to make.

Originally Posted by Eadam1985

i just started doing work at this resturant and had a walk in freezer that was icing up i couldnt figure out why defrost work and pressures were fine long story short the manager would shut off the fans and leave the door open when they would load the freezer.

The defrost fans have to be interlocked with the thermostat and the liquid line solenoid valve. Any time the switch is off the freezer pumps down. I can't imagine anyone with a brain wiring it without this simple protection.

Johnson Controls A419 works well. Solved two different icing issues without timers. Both older systems with high user activity.

Did not read through entire thread so my apologies if this has been covered. I always prefer controlling temp with a lpc for a few reasons.

1. Offers compressor protection
2. Kiss timeclock can't fail if it's not there
3. Customers can crank stat down but I control how low it will go
4. Saves nuisance calls from iced up coils due to door being left open or fans turned off because it's self regulated.
5. Maintains better product integrity
6. Better energy efficiency
7. Compressor life extended because it cycles better


Sidenote regarding blends

They are a bit trickier what you need to member is that they enter as a liquid and exit as a vapor and only in the center are they a true saturated state.

For example say you are looking for a co evaporation temp of 15degrees and your refrigerant has a corresponding bubble point of 10lbs and a dew point of 20lbs the correct co pressure is 15lbs.

What that does is compensates for the glide and should produce 15 degrees at the center point in your coil. It sounds more confusing then it is but it does work.

Originally Posted by traviscmatthews

With the technology today, and for best product temp control, its a simple solution. Thermostat, solenoid, and defrost clock. Defrosts are totally dependent on climate, but 4 times a day, at 45 minutes apiece will ensure a 100 percent clear coil, but not warm up enough that the customer will notice. If anyone asks you to anything different, they are cutting corners, and trying to save money on the install. If you're not going to do it properly on the install, don't bother. You seem like you have the right attitude. Keep up the good work, and don't listen to the guys wanting to save the customer $10, and cutting corners.

Way too much.

With the technology today, and for best product temp control, its a simple solution. Thermostat, solenoid, and defrost clock. Defrosts are totally dependent on climate, but 4 times a day, at 45 minutes apiece will ensure a 100 percent clear coil, but not warm up enough that the customer will notice. If anyone asks you to anything different, they are cutting corners, and trying to save money on the install. If you're not going to do it properly on the install, don't bother. You seem like you have the right attitude. Keep up the good work, and don't listen to the guys wanting to save the customer $10, and cutting corners.

Originally Posted by marter

pretty much every switch i see that kills the fans also kills the solenoid and puts the unit into pump down.

Saw an interesting one today. WIF has 3 disconnects and one toggle switch in the box. 2 evap coils 1 solenoid and tstat. 1 disconnect for fans only. 2 disconnects for heaters, 1 for each coil. Toggle switch kills power to solenoid and fans. Don't know why you would have an option to kill fans only or fans and sollenoid. Probably field engineered by a sparky.

pretty much every switch i see that kills the fans also kills the solenoid and puts the unit into pump down.