Freezer over freezing

[fixbear]

You say you checked the thermistors. So, it has to come down to control. What is the set point of the controller? A negative 25 is not an unreal freezer setting for certain products in long term storage. The other possibility would be the controller compressor relay has welded closed. But that would keep the compressor running even in defrost and you would have an ice buildup.

Klixon disc limits are used to cut off the defrost when the coil has thawed. They are also used to not restart the evaporator fans till the coil is sub-freezing to help keep product stabile.

[carlospavo]

Thanks for the reply fixbear. The set point was 10° when it went down to -25

On another try, I left it plugged for longer with set point 42° It kept over freezing past -35 It did build a block of ice all over the evaporator coil. I will check the controller compressor relay next

[fixbear]

That means the compressor is not stopping. Does it stop in defrost? If not, then you’ll have to replace the controller. Unless your good with bench work and have a soldering station. The compressor relay in the controllers are only 10 amp rated. Start load on a compressor is 17 times full run current. I like to see freezers with a separate relay in series with the controller. Very few manufacturers do that. As the compressor starting components age, especially with a dirty condenser, you wind up at the max of the Dixel controller.

How old is this cooler?

I believe there is a version of the Dixel that has a 20-amp relay for the compressor. Finding it is the difficult part.

[carlospavo]

The compressor does not stop on defrost either. The freezer was manufacture on 201. So about 8 years old. The Dixell controller looks like it was replace already before. I do not know how old the controller is. The only numbers that resemble a date on it are 001 #18/2019

Thank you so much for your input & help fixbear. I will replace the controller & update on it.

[fixbear]

Dixell controllers have been around for a long time now. There have been many changes to them including adding monitoring and alarm sensing. Also box remote recording. Venders will only have 2 to 3 models in stock. But that doesn’t mean you get one right for your box. Check that it has 20-amp compressor relay, fan relay, and defrost relay should be 8 amps. That will make it a low temp unit. Now you may also have to have a door switch to stop the fans when a door is opened. These are made to be either NO or NC. They also have different defrost time intervals. That is determined by the manufacturer when they design the box take down and evaporator design and how tolerable it is to moisture build-up. It will most likely be a XR60CX something. The auxiliary letters and numbers will determine that.

Oh, and make sure you have the polarity right on the thermistors.

[carlospavo]

Finally got the new controller installed. It is a Dixell XR06CX-4N1F1. It came with new thermistors & it has a 20 Amp compressor relay. The installation was straight forward. No need to add or modify any thing. After installation & set-up, the freezer works like a champ.

I took the old controller apart. It had internal corrosion on the circuit board. It seems like some liquid got inside corroded the board & burned some components.

Thank you fixbear for your help. I really appreciate it. You are a well of knowledge.

[fixbear]

At times I’ve seen many electrical parts that got damaged from cleaning agents. Especially ammonia-based products. They love to eat copper. And when wiping down the face of a cooler, the square edge of the controller acts like a squeegee. That then wicks into the internals. But the face looks nice.