Evaporator Freezing Up - Even Ice Build Up

  1. Always verify evaporator is clear of debris.
  2. Always check super heat and set to factory recommended settings. If in doubt. Set for an 8-12 degree superheat and always make sure that the compressor has a superheat that is recommended by manufacturer at compressor suction line to prevent thermal or physical break down.
  3. Is thermostats/pressure controls set and cycling properly?
  4. Check contactors contacts. Are they stuck?
  5. Is the liquid line solenoid normal or stuck open?
  6. Check evaporator air flow restriction due to damaged fins and/or incorrect fan rotation. Is there a door switch or additional bypass switch in circuit? This could be a cause for evap fans to remain off.
  7. Is ambient temperature within parameters?
  8. If no:

    Is this a remote outdoor unit?

    Be sure to test head master/head pressure control. Always insure that the head pressure is maintaining 90 degrees.
  9. Check to see if hot product is loaded. Is the equipment rated for this option? Has the customer been doing this for several years? If not, have customer reduce product that is loaded into refrigerated space or choose different equipment.
  10. Is door left open? although this is always an option, unless you actually see for yourself. Never assume this is the problem.
  11. Check door gaskets, however more refrigeration is rated to maintain with some leakage unless high ambient conditions exist.