START-UP
Step 1 — Check for Refrigerant Leaks
Proceed as follows to locate and repair a refrigerant leak and to charge the unit:
1. Locate leak and make sure that refrigerant system pressure has been relieved and reclaimed from both high-
and low-pressure ports.
2. Repair leak following accepted practices.
NOTE:
Install a filter drier whenever the system has been opened for repair.
3. Add a small charge of Puron (R-410A) refrigerant vapor to system and leak-test unit.
4. Recover refrigerant from system and evacuate to 500 microns if no additional leaks are found.
5. Charge unit with Puron (R-410A) refrigerant, using an accurate scale. Refer to unit rating plate for required
charge.
Step 2 — Start-Up Cooling and Make Adjustments
Complete the required procedures given in the Pre-Start-Up section before starting the unit. Do not jumper any safety
devices when operating the unit. Do not operate the unit in cooling mode when the outdoor temperature is below 40°F
(4.4°C) (unless accessory low-ambient kit is installed). Do not rapid cycle the compressor. Allow 5 min. between “on”
cycles to prevent compressor damage.
CHECKING COOLING AND HEATING CONTROL OPERATION - Start and check the unit for proper cooling control
operation as follows:
1. Place room thermostat SYSTEM switch in OFF position. Observe that blower motor starts when FAN switch is
placed in ON position and shuts down within 60 sec. when FAN switch is placed in AUTO position.
2. Place SYSTEM switch in COOL position and FAN switch in AUTO position. Set control below room
temperature. Observe that compressor, outdoor fan, and indoor blower motors start. Observe that cooling
cycle shuts down when control setting is satisfied.
3. If unit is equipped with electric heat, place system switch in HEAT position. Observe that indoor fan energizes.
Set control above room temperature. Observe that heating cycle shuts down when control setting is satisfied.
4. When using an automatic changeover room thermostat, place both SYSTEM and FAN switches in AUTO
positions. Observe that unit operates in Cooling mode when temperature control is set to call for Cooling
(below room temperature), and unit operates in Heating mode when temperature control is set to call for
Heating, if equipped with electric heat (above room temperature).
Step 3 — Refrigerant Charge
Refrigerant Charge — The refrigerant system is fully charged with Puron (R-410A) refrigerant and is tested and factory
sealed. Amount of refrigerant charge is listed on unit nameplate and in Table 1. Unit must operate a minimum of 15
minutes before checking charge.
NOTE
: Adjustment of the refrigerant charge is not required unless the unit is suspected of not having the proper Puron
(R-410A) charge.
NOTE
: Unit sizes 36-48 have fixed orifice refrigerant metering devices; the 60 size has a TXV. There is a different
charging procedure for both expansion devices. Refer to the correct procedure for your unit.
NO CHARGE - Use standard evacuating techniques. After evacuating system, weigh in the specified amount of
refrigerant (refer to Table 1).
Low Charge Cooling 50ZPM Unit 36-48, Fixed Metering Device:
1. Operate unit a minimum of 10 minutes before checking charge.
2. Measure suction pressure by attaching an accurate gauge to compressor suction side service port.
3. Measure suction side temperature by attaching an accurate thermometer type or electronic thermometer to
suction line about 10 in. from compressor.
4. Measure outdoor air dry-bulb temperature with thermometer.
5. Measure indoor air (return air) wet-bulb temperature with a sling psychomotor or electronic equivalent.
6. Using Superheat Charging Table find outdoor temperature and indoor air wet-bulb temperature. At this
intersection note superheat. Where a dash (-) appears on table do not attempt to charge unit under these
conditions or refrigerant slugging may occur. In this situation refrigerant must be evacuated and weighed in.
See rating plate for charge quantity.
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