Product data

SERVICE – 38HDC, 38QR, & 38BK018,024
WARNING: Before performing recommended maintenance, be sure unit main power switch is turned off. Failure to do so
may result in electrical shock or injury from rotating fan blade.
OUTDOOR FAN
A reinforced wire mount holds the outdoor fan assembly in position. See Fig. 7 for Cooling Units and Fig. 8 for Heat pump
Units for proper mounting positions.
HIGH-PRESSURE RELIEF VALVE
Valve is located in compressor. Relief valve opens at a pressure differential of approximately 450 +/- 50 psig between suction
(low side) and discharge (high side) to allow pressure equalization.
INTERNAL CURRENT AND TEMPERATURE SENSITIVE OVERLOAD
Control resets automatically when internal compressor motor temperature drops to a safe level (overloads may require up to
45 minutes to reset). When an internal overload is suspected of being open, check by using an ohmmeter or continuity tester.
PUMPDOWN PROCEDURE
The system may be pumped down in order to make repairs on low side without losing complete refrigerant charge.
1. Attach pressure gage to suction service valve gage port.
2. Front seat the liquid line valve.
CAUTION: The outdoor unit holds only the factory designated amount of refrigerant. Additional refrigerant may cause
units to relieve pressure through compressor internal pressure relief valve (indicated by a sudden rise of suction pressure)
before suction pressure reaches 5 psig. If this occurs, shut off unit immediately, front seat the vapor valve, and remove and
recover excess refrigerant following accepted practices.
3. Back seat valve, start unit, and run until suction pressure reaches 5 psig.
4. Shut unit off and front seat suction valve.
5. De-pressurize low side of unit and recover refrigerant following accepted practices.
FILTER DRIER (If Installed)
Whenever the accessory, field-installed moisture liquid indicator (if installed) shows presence of moisture, replace the filter
drier. If no indicator is installed, replace the filter drier whenever system has been opened for service or maintenance.
HIGH-PRESSURE SWITCH
This switch, located on discharge line, protects against high discharge pressures caused by such events as overcharge,
outdoor fan motor failure, system restriction, etc. It opens on pressure rise at about 426 psig. If system pressures go above
this setting during abnormal conditions, the switch opens.
WARNING: DO NOT attempt to simulate system abnormalities. High pressures pose a serious safety hazard.
The High-pressure switch is checked with an ohmmeter. If system pressure is below 320 psi (cooling) or 426psi (heat pump)
switch shows continuity. The high pressure switch will reset automatically after the CLO (compressor lockout switch) has
been reset, and the time delay device has completed its timing cycle.
NOTE: If pressure switch needs to be replaced, there is a Schrader valve located under the switch so that system will not
need to be evacuated.
LOW-PRESSURE
This switch is mounted on the vapor line for Cooling Only Units and the liquid line for Heat Pump Units, and has fixed, non-
adjustable settings. On Heat Pump units, this switch is bypassed during defrost mode, and also for the first 2 minutes of
heating operation after defrost. This is accomplished by a time delay relay to prevent nuisance tripping of the loss-of-charge
switch. To check pressure switch, attach pressure gage to service valve gage port. Slowly close shutoff valve and allow
compressor to pump down. Do not allow compressor to pump down below 2 psig. Compressor should shut down when
pressure drops to cutout pressure as shown in Physical Data Section #8, and should restart when pressure builds up to cut-in
pressure shown, after CLO (compressor lockout switch) has been reset and accessory Time Guard device has completed its
timing cycle. MORE ON NEXT PAGE