Do you have any questions?

We are here to answer your questions: AND Klima

  2. i) The thermostat is set at 35°C, so if the temperature inside the cabinet is lower, the compressor and external fan will not operate. It may appear as if the device is “not working” because the air circulating inside the cabinet is not being cooled.
  3. ii) Setting the thermostat to 35°C ensures the proper operation of the air conditioner and the electronics on the control panel, preventing condensation. Therefore, it is a crucial operational parameter and a warranty requirement.
  5. i) Place the thermostat according to the indications provided in the instruction manual.
  6. ii) Ensure that the air conditioner operates at the nominal voltage level.

iii) For air conditioner control units powered by three-phase supply (Rotary Compressors), ensure that all phases are correctly connected and not reversed (refer to the wiring diagram – K1 = Phase Sequence Control Relay). If the phases are reversed or one of them is not connected, the air conditioner control unit will remain off. If there is a display on the air conditioner, it will also be off.

  1. iv) If the air conditioner control unit is equipped with “Door Open Control,” make sure the door contact is connected. If not, short-circuit the relevant terminals on the external terminal strip (X9-1 + X9-2). If the air conditioner control unit is equipped with cables for power supply and signals, short-circuit the 2 red wires of the 5-way multi-pole cable (refer to the wiring diagram – SQP = Door contact).

If the SQP contact is open (cabinet doors are open), the air conditioner control unit will remain off. If there is a display on the air conditioner, it will also be off.

After checking the above points:

  1. v) When the air conditioner is powered on, ensure that the internal fan (Evaporator Battery Side) is rotating (air circulation inside the cabinet).

To perform the test, the temperature on the thermostat should be lowered as follows:

  1. i) Electromechanical thermostat:

(a) Loosen the minimum temperature adjustment stop screw (only available on models produced before 2000) to allow the thermostat to reach the start of the scale.

(b) Rotate the adjustment screw counterclockwise (using a screwdriver) to reach the cut-off point where the compressor and external fan start operating.

  1. ii) Non-display electronic thermostat:

(a) Rotate the adjustment screw counterclockwise to reach the cut-off point.

iii) Display electronic thermostat:

(a) Adjust the temperature from the display (refer to the operation manual and/or the second page of the wiring diagram for the process).

  1. iv) The compressor and external fan (Condensation Battery Side) will start operating, and after approximately 15 minutes, cooled air will be emitted from the outlet holes (the temperature of the air will vary depending on the temperature inside the cabinet, ambient temperature, humidity, and the cleanliness of the condensation battery).

After confirming the proper operation of the air conditioner as described above, reset the internal control thermostat (electromechanical or electronic) to 35°C. If there is a stop screw, reposition it, otherwise, the thermostat may break.


It is possible to check the operation of the thermostat using a digital thermometer and a wire detector:

  1. i) Place the detector of the digital thermometer next to the air conditioner fan inside the cabinet and verify that the temperature reading matches the temperature at which the thermostat is set to respond.
  2. ii) Wait for 10 minutes before performing the operation.

iii) For the electromechanical version, slowly turn the thermostat adjustment screw clockwise (from 0 to maximum) to reach the cut-off point, then check if the value on the thermostat matches the value on the digital measurement device.

  2. i) Start the air conditioner and follow the instructions for TEST #1 called “Operation of the Air Conditioning Control Unit” if necessary.

WARNING: THE TEST SHOULD BE PERFORMED WITH THE CABINET COMPLETELY CLOSED. No measurements should be taken inside the cooled cabinet.

  1. ii) Ensure that the model is equipped with original MKS filters and that they are clean.

iii) Wait for a minimum of 15 minutes before proceeding with the test.

  2. i) Measure the ambient temperature at the inlet of the external condenser circuit (Wall model: lower part of the external cover / Roof model: slots on the cover).
  3. ii) Measure the air temperature at the outlet of the condenser (Wall model: upper part of the external cover / Roof model: slots on the roof or long side of the cover). The air temperature ‘Tu’ will be higher than the ambient temperature ‘Ta’ (Tu > Ta).

iii) Complete the table below and send it to our customer service department. Our department will provide you with a quick response, including a brief report on the cooling capacity of the air conditioner.

  2. i) This test should be performed after the air conditioning unit with a minimum protection class of IP 54 has been running for at least 1 HOUR with the doors CLOSED. Additionally, it is advisable to select or simulate the Maximum Ambient Temperature Conditions of the final installation location.
  3. ii) If the model is equipped with filters, ensure that they are MKS originals and clean.
  5. i) Check the thermostat setting (it should be set to 35°C).
  6. ii) Place a thermometer at the hottest point inside the cabinet, leave it there for approximately one hour, and record the temperature.
  8. i) If the temperature does not exceed 35°C / 40°C, the air conditioning unit is correctly sized.
  9. ii) If the temperature exceeds 40°C, the air conditioning unit is undersized (insufficient power). In this case, a new sizing calculation is required (use MKS website ( or request the “Air Conditioning Unit Sizing” form).

iii) If the temperature remains around 35°C AND THE COMPRESSOR STARTS MORE THAN 6 TIMES PER HOUR, the air conditioning unit is oversized and will have a shorter operating life (this is inversely proportional to the number of compressor starts). In this case, a new sizing calculation is also required.

  2. i) Ensure that the air conditioning unit is in a completely level position (with a maximum tolerance of 2°).
  3. ii) Condensation water is formed by extracting humidity from the air inside the cooled cabinet and does not occur without the entry of humid air from the outside.

iii) In situations where the humidity in the air is high, and the temperature inside the cabinet is at least 10°C lower than the surrounding environment, condensation forms on the cabinet walls.

  1. iv) When the air conditioning unit is first started or each time the cabinet is opened, the air inside removes humidity and condensation is discharged outside, where the compressor heat evaporates the water.
  2. v) As a result, the air inside the cabinet is dehumidified (dehydrated) and remains so until fresh air enters from the surroundings.
  3. vi) If the humidity is particularly high, the use of door contact is strongly recommended (the air conditioning unit must not operate with the doors open, as it would result in spraying water inside due to accumulated high humidity on the surface of the evaporator battery).

If the air conditioning unit consistently produces excessive condensation, perform the following checks:

  1. i) The cabinet must have a minimum IP54 protection class. In particular, there should be no openings, gaps, or holes in the lower part of the cabinet.
  2. ii) Once condition i) is fulfilled, proceed with the following steps:

iii) The air conditioning unit should operate with the cabinet doors closed. If there is a “door open” warning system, ensure that it operates correctly.

If the cabinet doors are open, stop the air conditioning unit.

  1. iv) The thermostat of the air conditioning unit should not be set below 35°C. If it is, revert to the factory settings (as per the user manual).
  3. i) Condensate drain pipe:

(a) It should never be located at a higher position than the air conditioning unit’s outlet connection point.

(b) The ends should be open.

(c) It should be above the water level.

(d) It should never be placed on the cabinet roof due to the concave structure caused by the weight of the air conditioning unit.

Accumulated outside condensation and any liquid can seep into the interior of the cabinet.

(e) Reinforce and ensure the waterproofing of the cabinet roof if necessary.

If the above procedures do not successfully reduce condensation production, please contact our after-sales service department.



Create a vacuum in the refrigeration circuit and ensure that the pressure reaches 9 Pa. Use the two compressor valve connections (remove the delivery valve where the pressure switch is connected) for this purpose. [1 Pascal (Pa) = 1 x 10-5 Bar].


Stop the vacuum pump and wait for the pressure to stabilize for 10 seconds. If the pressure exceeds 110 Pa during this period, it indicates a leak.


If the pressure remains below this value, proceed to step (6).


Search for leaks by pressurizing the circuit with nitrogen gas at 20 bar.


Inspect all connections and brush them with water and soap.


Repeat the procedure after repairing the leak.


Fill the system through the input valve (remove the delivery connection) with the gas type and quantity indicated on the air conditioning unit’s data sheet. If the data sheet is unreadable, contact us to obtain the necessary information for this procedure.


Remember to tighten the protective caps on the valves securely.