How to troubleshoot the LPEr and HPEr alarm codes on a Sinoclima truck refrigeration unit?
LPEr Alarm
1,System pressure is too low:
Below the lower limit of the pressure switch, just turn on the unit, the LPEr alarm immediately, indicating that there is no refrigerant in the system, there are leaks, need to check the leaks,
exclude leaks before further replenishment of refrigerant oil, vacuum, refrigerant; if the alarm occurs after the operation to a low temperature, it means that the amount of refrigerant is too low, or the expansion valve opening is too small, or the expansion valve has a dirty blockage or ice blockage, after inspection and processing to continue to use;
2,Low-pressure switch damage:
Can not close under normal pressure; confirmation method: in the system refrigerant is sufficient, use a multimeter to directly measure the pressure switch two contacts to see whether it is connected, such as no connection indicates that the pressure switch is damaged, need to be replaced;
3,Low pressure switch disconnection:
The low pressure switch is intact, but the two wires connecting the low pressure switch have a disconnection in the middle;
4,Controller damage:
The basis for judgement, in the system under normal pressure, from the back of the controller plug directly measure the low pressure switch line (generally brown line) and the black negative line to see if it can conduct, that the wiring harness and pressure switch are normal, and here the pins are intact and in place, then the controller is damaged, replace the controller.
5,R134A Chill unit pressure switch:
While the refrigeration units do not have a low pressure switch, the low pressure switch line is connected directly to the negative pole, use a multimeter to measure the controller after the brown line and the black line is normally connected, if not, check the line;
If it is connected and the pins are firm and normal, it indicates that the regulator is damaged, replace the regulator.
