Symptom

Possible cause

Check & Test

Remedies

Totally Dead:
If neither the fan nor the compressor operate with the thermostat on.

 If no flashes start with step A.

Faulty Thermostat

Step A: Make sure the thermostat and power are on.

 Is the thermostat on? Does it “click” when switching to off?   No!

By pass the thermostat at the compressor.  Connect terminals T and C or the connectors at the end of the yellow speed resister harness if fitted.

Thermostats are make and break switches. Use an ohmmeter to check thermostat wires for continuity (on).

If Compressor and fan run replace the thermostat. 

If compressor and fan still do not run, go to step B.

Totally Dead:
If neither the fan nor the compressor operate with the thermostat on.

Single Flash

No power to unit 

Step B: Do you have power to the unit?   

Power cables could be reversed.   

Note: Do not apply battery power to any Compressor Module terminals other than the top two labeled with a large (-) (+). Doing so may destroy the Module. 

Measure the battery voltage at the compressor connections.  

If The Unit Has Power the fan will run or the fault light will flash when switched on and power is available. 

Check for fault code on the small red LED on the data plate end of the cabinet.  Early units had internal LED or none.  

Single flash is low voltage when trying to start.  

Check voltage or start charging batteries to raise the voltage. Also check for loose wires or a corroded connection. 

Check amp draw to confirm that the compressor is operating.

Totally Dead:
If neither the fan nor the compressor operate with the thermostat on.

Two Flashes  

Faulty Fan

Check for fault code on the small red LED on the data plate end of the cabinet.  Early units had internal LED or none. 

Two flashes means the fan circuit is over loaded.

Unplug the fan to see if the compressor starts and fault is corrected. If the compressor runs replace the fan.  All units use a 12-volt fan (even 24 volt systems).

Symptom

Possible cause

Check & Test

Remedies

Compressor does not start:
The fan runs but the compressor does not start.

Three Flashes

Overcharged   
Has charge been added?

Faulty module 

Three Flashes: This fault may also occur when the compressor is trying to start a warm system.  Several attempts and then start up can be normal.

Check for fault code on the small red LED on the data plate end of the cabinet.  Early units had internal LED or none.  

Three flashes. The compressor may be overloaded by excessive refrigerant charge. Has charge been added?  This fault can also occur if wiring is weak or switch contacts are worn. The compressor cannot get up to speed on low voltage.   

If charge has been added, remove some refrigerant until flashing stops.  

If three flashes show and charge has not been added, i.e. the compressor has been working well, then the module is weak and will need to be replaced.  

See module replacement  data sheet. 

Partial Cooling:
If the compressor runs and cools but is not cooling the entire plate when left on.    

Frost will form on the coldest place first. This frost is moisture.  Moisture will eventually leave suspension and the air in the cabinet will become very dry after a time.  Check the temperature of the cold plate(s) not the frost level or amount of coverage. Sometimes only one plate in a freezer will be frosted for it has picked up all the moisture.

Expansion valve setting :

The expansion valve is the brass device connected to the cold plate or one of the freezer plates.  It is under a cover on the single plate systems and the Freezer Bin. 

Low on refrigerant  

Remove the cover as needed by removing all related screws and perhaps the thermostat knob if so fitted.  The expansion valve has a plastic moisture cap on it that will have red heat shrink on it until it is first adjusted in the field. Tradewinds will not have the heat shrink.  Remove the heat shrink by cutting it away with a small knife.  Do not cut into the plastic cap.  Remove, by unscrewing, counterclockwise, the cap, being careful not to squeeze the brass knob under it and turning it.  Mark the brass knob with a marker in order to return it to this position if needed.

See valve testing and valve setting data sheet.

First test: Turn the adjustment knob ¼ turn clockwise and replace the moisture cap.  Be sure the cap seals against the rubber “O” ring.  Observe the cooling on the cold plate.  More of the cold plate should cool if the compressor remains on.  If no noticeable increase in cooling is indicated within an hour the system is low on refrigerant.  Re-set the valve to the original position and re-cap it. Refer to re-charging instructions.  

Leak check and add or re-charge with refrigerant. 

Symptom

Possible cause

Check & Test

Remedies

Lack of airflow 

Excessive heat  

Faulty Module

Four and five flashes would indicate lack of air or excessive operating temps like an enclosed locker or hot engine space.  

Check the water pump if air and water-cooled. 

This fault will correct itself when the unit cools off.  

If it does not, replace module.

Compressor is noisy

Excessive refrigerant charge

 Air in the system

The compressor is silent.  Any audible noise has been tracked to excessive refrigerant charge or air introduced to it by leaks or improper servicing.    

Fix: Evacuate and re-charge with the correct amount of refrigerant.

Compressor will not turn off

Faulty Thermostat

Incorrect Thermostat probe installation

The thermostat may have continuity (on) but might not turn off. The system may run continually. Frost or active cooling may develop from the return line tube on the plate (second plate) to the compressor.

Check that the compressor will turn off with the thermostat knob in the off position.  

Remote Thermostats work best when any excess capillary tube is in the cold space. 

If the thermostat is a Remote or ETT the bulb must be clipped on the side or bottom of the cold plate.  The best location would be the coldest section of the plate. 

If the compressor does not turn off with the thermostat knob in the off position, replace the thermostat. 

Check that the thermostat bulb is in good thermal contact with the cold plate. The bulb probe must be on the second plate in a two-plate system. This is the plate without the valve.   

No Cooling:
If the compressor is running and there is no cooling. 

With the compressor running for a few minutes some cooling will be evident when touching the cold plate near or at the expansion valve. 

See the following sections:
Service port leaks
Quick connect leaks
Swagelok fitting leaks 

Leak check and re-charge with refrigerant.