After inspecting the electrical controls and wiring, replace all the panels. Start the unit, and observe at least one
complete cooling cycle to ensure proper operation. If discrepancies are observed in operating cycle, or if a suspected
malfunction has occurred, check each electrical component with the proper electrical instrumentation. Refer to the unit
wiring label when making these checks, See Typical Wiring Diagram.
Refrigerant Circuit -
Inspect all refrigerant tubing connections and the unit base for oil accumulation annually.
Detecting oil generally indicates a refrigerant leak.
If oil is detected or if low cooling performance is suspected, leak test all refrigerant tubing using an electronic leak
detector, halide torch or liquid-soap solution. If a refrigerant leak is detected, refer to Check for Refrigerant Leaks
section. If no refrigerant leaks are found and low cooling performance is suspected, refer to Checking and Adjusting
Refrigerant Charge section.
Indoor Airflow -
The airflow does not require checking unless improper performance is suspected. If a problem exists,
be sure that all supply-and return-air grilles are open and free from obstructions, and that the air filter is clean.
Metering Devices -
Refrigerant cooling metering device is a piston (036-048) or TXV (060) located upstream of the
indoor coil distributor assembly.
High Pressure Switch -
The high-pressure switch is located in the discharge line and protects against excessive
condenser coil pressure. It opens at 650 psig (4482 kPA).
Low Pressure Switch -
The low-pressure switch is located in the suction line and protects against low evaporator coil
pressure. It opens at 54 psig (372 kPA).
To check switches: 1. Turn off all power to unit, 2. Disconnect leads on switch., 3. Apply ohmmeter leads across
switch. You should have continuity on a good switch.
Puron (R-410A) Compressor -
The compressor used in this product is specifically designed to operate with
Puron (R-410A) refrigerant and cannot be interchanged.
The compressor is an electrical (as well as mechanical) device. Exercise extreme caution when working near
compressors. Power should be shut off, if possible, for most troubleshooting techniques. Refrigerants present
additional safety hazards.
Compressors vary in type by unit size. See Table 5 below for compressor type by size.
Table 5 – Compressor Type and Oil
Unit 50ZPM
Compressor Type
Manufacturer Suggested Oil Type
36
Reciprocating
Hatcol 32BCE Polyolester (POE)
48
Scroll
Mobil 3MAF-POE
60
Scroll
Mobil 3MAF-POE
WARNING
EXPLOSION, SAFETY AND ENVIRONMENTAL HAZARD
Failure to follow this warning could result in personal injury, death or equipment damage.
This system uses Puron (R-410A) refrigerant which has higher operating pressures than R-22 and other
refrigerant. No other refrigerant may be used in this system. Gauge set, hoses, and recovery system must be
designed to handle Puron (R-410A). If you are unsure, consult the equipment manufacturer.
WARNING
EXPLOSION HAZARD
Failure to follow this warning could result in personal injury or death and/or property damage.
Wear safety glasses and gloves when handling refrigerants. Keep torches and other ignition sources away from
refrigerants and oils.
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