Component Testing; Verifying High Pressure Switch And Low Pressure Protec- Tion Operation - Lennox EL23XCV Series Manual

Component Testing

Verifying High Pressure Switch and Low Pressure Protec-
tion Operation .................................................................53
Verifying Suction Pressure Transducer Operation..........54
Compressor Operation, Checkout and Status / Error
Codes .............................................................................58
Crankcase Heater, Checkout and Status / Error Codes .60
Compressor Sound Cover ..............................................63
Suction Line Filter Drier ..................................................63
Verifying High Pressure Switch and Low Pressure Protection Operation
OPERATION:
The unit's pressure S4 high pressure switch is factory wired into the control on the HPS terminals.
NOTE - The EL23XCV does not have a low pressure switch and LPS terminals are not jumpered. The unit has a suction
pressure transducer that emulates the low pressure switch with a cut-out of 40 PSIG and a cut-in of 90 PSIG. This provide
the same protection as a tradition low pressure switch. If the event the suction pressure transducer fails, back up protec-
tion is provided by the suction temperature sensor and will open at 25F.
Low Suction Pressure Protection - See figure 26 for low suction pressure protection sequence of operation.
High Pressure Switch (HI-PS) - See figure 27 for high pressure switch sequence of operation.
The following pressures are the auto-reset event value triggers for low and high pressure thresholds:
• High Pressure (auto-reset) - trip at 590 psig; reset at 418.
• Low Suction Pressure Protection (Suction pressure transducer emulates LPS) (auto-reset) - trip at 40 psig; reset at 90.
CHECKOUT - S4 High Pressure Switch
Using a multimeter set to ohms with the terminals disconnected from the control board, check the resistance between the
two terminals of the pressure switch. If the resistance reading is 0 ohms, the switch is closed.
Component Testing Table of Contents
Pressure Switch Event Settings
FIGURE 25. Verifying High Pressure Switch Operation
Liquid Line Filter Drier ....................................................64
Top Cap Switch Operation ..............................................64
Reactor Operations ........................................................65
Outdoor Fan Operation...................................................65
Outdoor Control Operation ............................................ 67
Unit Sensor Operations ................................................. 68
DC Inverter Control Operation ....................................... 71
S4
HIGH
PRESSURE
SWITCH
Page 53