37
38AUDC with SVR Relays
With no thermo s tat demand, there will be no voltage at
LVTB--A1; HGBP SOLENOID is de--energized and solenoid
valve remains closed, preventing bypass vapor from the
desu p erh eating tank to enter the suction line at the
compressor .
On a thermostat call for first--stage cooling, LVTB terminal
Y1 is powered; when CADM 1 is satisfied, compressor
contacto r C1 and Solen o id Valve Relay SVR 1 are ener g ized .
SVR1 contacts close, providing 24--v to LVTB terminal A1,
then through H GBP RELAY NC contacts to H GBP
SOLENOID. HGBP solenoid valve opens, allowing bypass
vapor from the desuperheating tank to enter the compressor
suctio n por t.
If thermostat calls for second stage cooling, LVTB terminal
Y2 is powered; when CADM2 is satisfied, compressor
contactor C2, Solenoid Valve Relay SVR2 and HGBP
RELAY are ener gized . HG B P RELAY NC contacts open,
de--energizing the HGBP SOLENOID; solenoid valve closes,
blocking bypass vapor from the desuperheating tank and unit
runs at full cooling capacity.
The model 38AUDC also includes the 32LT Motormaster
low ambient control as a standard feat ure. Refer to
Appendix C for information on the Motormaster control.
All Units
If either the Low Pr es s ur e Switch or High Pres s u re Switch
opens while thermostat output Y1 or Y2 remain energized,
the compressor contactor is de-energized, the compressor
sto ps and liquid line solen oid is de-energized (valve closes) .
CADM initiates a TRIP event (cooling demand s en s ed at
CADM terminal Y but no curren t is measur ed at T1, T2, T3
motor sens o rs ) ; CAD M relay opens and RED LED is
illuminated. TRIP condition maintains lockout of compress or
operatio n until CAD M is manually reset. Reset CADM by
cycling unit main pow er.
Complete system shutdown may be caused by loss of main
power , open compressor internal overload, open
low-pressure or high-pressure switch, or a fault detected by
the CADM logic. Compressor operation w ithout cooling
may indicate the compress o r’ s AS TP featur e is active;
disconnect unit power and allow compressor to cool. S ee
Serv ice section for further details .
Cooling, Unit With Economizer —
Refer to fan coil unit installation instructions and
economizer accessory installation instructions for
operat ing sequences when system is equipped with
accessory economizer.
Heating —
Refer to fan coil unit installation instr uctio ns and access or y
heating device installatio n instru ction s for operating
sequences in heating mode.
ROUTINE SYSTEM MAINTENANCE
These items should be part of a routine maintenance
prog r am, to be checked every month or two, until a specif ic
sched u le for each can be identified fo r this ins tallatio n:
Quarterly Inspection (and 30 days after initial start) —
Indoor section
S Condenser coil cleanliness checked.
S Return air filter replacement
S Outdoor hood inlet filters cleaned
S Belt tension checked
S Belt condition checked
S Pulley alignment checked
S Fan shaft bearing locking collar ti ghtness checked
S Condensate drain checked
Seasonal Maintenance —
These items s hould be checked at the beginning of each
season (or more often if local conditions and usage patterns
dictate):
Air Conditioning
S Condenser fan motor mounting bolts tightness
S Compressor mounting bolts
S Condenser fan blade positioning
S Control box cleanliness and wiring condition
S Wire terminal tightness
S Refri gerant charge leve l
S Evaporator coil cleaning
S Evaporator blower motor amperage
Heating
S Power wire connections
S Fuses ready
S Manual-reset limit switch is closed
Economizer or Outside Air Damper
S Inlet filters condition
S Check damper travel (economizer)
S Check gear and dampers for debris and dirt
SER VICE
Refrigeration System
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in damage to
equipment.
This system uses Puron
R
refrigerant which has hi gher
pressures than R-22 and other refrigerants. No other
refrigerant may be used in this system. Gage set,
hoses, and recovery system must be de signed to
handle Puron. If you are unsure consult the equipment
manufacturer.
CAUTION
!
38AU
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