What to Do if Your Enclosure Air Conditioner Overheats or Isn’t Cooling


If your enclosure air conditioner is not performing optimally, you need to attend to it promptly. Any delay may cause electrical enclosure overheating, potentially resulting in equipment failure and loss in production. The fault may be minor and easily identified. Before calling for specialist support, have your maintenance staff perform these simple checks because they may be able to repair the air conditioner themselves.

First Steps

The first step should be to check and note the enclosure temperature on the digital controller display. At the same time, check that the set point has not been inadvertently adjusted and that it is below the enclosure temperature. If the enclosure temperature is above 110 ºF, it may be wise to switch the electrical enclosure off to prevent equipment damage until the reason for the overheating has been established and rectified.

Establish if any of the following alarm signals are displayed as these will indicate the reason for the fault:

  • P1: Indicates an enclosure temperature probe fault.

  • P2: Indicates a condenser temperature probe fault.

  • HA: The maximum enclosure temperature has exceeded 105 ºF for 3 minutes. Note there is a 30 minute start-up delay.

  • LA: The enclosure minimum temperature has been lower than 45 ºF for 3 minutes. Note there is a 30 minute start-up delay.

  • HA2: The condenser temperature has exceeded 145 ºF for more than 3 minutes.

  • LA2: The condenser temperature has been below 50 ºF for more than 3 minutes

  • CA: The evaporator coil pressure is low.

  • noP“: The wrong probe has been selected, reprogram the correct probe.

If HA2 and CA are showing, the compressor will have tripped and cannot be restarted until the corresponding fault has cleared and a 5 minute delay time has elapsed.

Refer to the technical manual for the air conditioner. If the air conditioner compressor is off, it will restart once the fault condition is cleared.

If the Unit Is Not Running

If the air conditioner isn’t running as evidenced by no display on the controller and the evaporator fan is not working, check the following:

  • Is the power switch on: Confirm that the power switch is on. It’s usually visible from inside the electrical enclosure.

  • Is there power: Make sure the supply fuse is not blown or the circuit breaker tripped. If a door kill switch is fitted, verify that it’s working.

  • Correct voltage: In the case of a newly installed unit, ensure the supply voltage is as specified on the air conditioner’s nameplate.

Unit Running but Overheating

If the air conditioner is running but the enclosure temperature is too high or the air conditioner itself is very hot, perform the following checks:

  • Filter: Find out if the condenser inlet air filter is clogged; if so, clean or replace it.

  • Condenser and evaporator fans: Make sure both fans are running; if not, verify they are connected and replace them if necessary.

  • Dirty condenser: Is the condenser coil fouled or dirty; clean if necessary.

  • Iced evaporator: Check if there’s ice on the evaporator coil; if so, switch the unit off and clear the ice. If icing continues, the unit may be low on refrigerant gas.

  • Air leaks: Confirm the enclosure doors shut properly and there are no air leaks in the enclosure and between the enclosure and the air conditioner; seal any leaks found.

  • Capacity: It’s possible the air conditioner is undersized; measure the evaporator coil temperature, verify the heat load, and contact Thermal Edge customer support.

Unit Not Cooling

If the enclosure air conditioner has power and is running, but is not cooling, check the following:

  • Digital controller: Establish if any alarms are displayed; if so, refer to the manual to establish what they mean and repair as necessary. Ensure the set point is set below the ambient temperature.

  • Is the compressor running: If the compressor isn’t running, use a meter to confirm there’s voltage at the terminals. If there is no power, check the contactor and contactor coil and replace if necessary.

  • Compressor thermal relay: Ensure the thermal relay, which is mounted on the compressor, is allowing power to the compressor; replace if open-circuit.

  • Evaporator fan: Check that the evaporator fan is running, if it isn’t, replace it.

Additional Support

Refer to the air conditioner enclosure manual for additional information and to locate and identify components. If the fault cannot be found, or repairs require the services of a refrigeration technician, contact Thermal Edge customer support or call in a competent refrigeration technician to carry out the required repairs.