Specifications
Refrigerant Feed Components ...............51
Thermostatic Expansion Valve (TXV) .........51
Moisture/Liquid Indicator ....................51
Filter Drier ..................................51
Liquid Line Service Valve ....................51
Compressor Discharge Service Valve ........51
Protective Devices ..........................51
• COMPRESSOR PROTECTION
• EVAPORATOR-FAN MOTOR PROTECTION
• CONDENSER-FAN MOTOR PROTECTION
• HIGH- AND LOW-PRESSURE SWITCHES
Relief Devices ..............................51
Control Circuit, 115 V .......................51
Control Circuit, 24 V ........................52
Electric Heat ................................52
• OVERCURRENT
• OVERTEMPERATURE
TROUBLESHOOTING, CV UNITS ...........52-57
Economizer .................................52
• MOTOR CHECKOUT
• CONTROL BOARD CHECKOUT
Control Board Checkout .....................53
• BASIC CHECK
• DETAILED CHECK
• ECONOMIZER BOARD CONTINUITY CHECK
TROUBLESHOOTING, VAV UNITS ..........58-62
VAV Diagnostic Information ..................58
• CODE 30: REAL TIME MEASUREMENT FAILURE
• CODE 51 TO 56: COMPRESSOR FAILURE
• CODES 59 AND 60: LOW-PRESSURE SWITCH
• CODES 63 AND 64: OIL PRESSURE SWITCH
• CODE 70: ILLEGAL UNIT CONFIGURATION
• CODES 71 TO 81: THERMISTOR FAILURE
• CODE 82: LEAVING-AIR TEMPERATURE SET
POINT FAILURE
• CODE 83: ECONOMIZER FEEDBACK
POTENTIOMETER FAILURE
• CODE 84: RESET LIMIT POTENTIOMETER
FAILURE
• CODE 85: DEMAND LIMIT POTENTIOMETER
FAILURE
• CODE 86: MINIMUM POSITION ECONOMIZER
POTENTIOMETER FAILURE
• CODE 87: WARM-UP TEMPERATURE SET POINT
FAILURE
Electronic Controls Checkout ................60
• PROCESSOR BOARD CHECKOUT
• RELAY BOARD CHECKOUT
• DISPLAY BOARD CHECKOUT
• TWO-STEP DEMAND LIMIT MODULE
START-UP CHECKLIST .....................CL-1
SAFETY CONSIDERATIONS
Installation and servicing of air-conditioning equipment
can be hazardous due to system pressure and electrical com-
ponents. Only trained and qualified service personnel should
install, repair, or service air-conditioning equipment.
Untrained personnel can perform basic maintenance func-
tions of cleaning coils and filters and replacing filters. All
other operations should be performed by trained service per-
sonnel. When working on air conditioning equipment, ob-
serve precautions in the literature, tags and labels attached
to the unit, and other safety precautions that may apply.
Follow all safety codes. Wear safety glasses and work gloves.
Use quenching cloth for unbrazing operations. Have fire ex-
tinguisher available for all brazing operations.
Before performing service or maintenance operations on
unit, turn off main power switch to unit. Electrical shock
could cause personal injury.
On 50DK units the evaporator fan can start at any time
after the initialization period when the timeclock places
the unit in the occupied mode.
Always turn power to unit off before performing any
service or maintenance.
INSTALLATION
This book contains instructions for 50DJ,DW constant vol-
ume (CV) units and 50DK,DY variable air volume (VAV)
units.
Rigging and Unit Placement — Inspect unit for trans-
portation damage. File claim with transportation agency. Do
not drop unit; keep upright. Use spreader bars over unit to
prevent sling or cable damage. Rollers may be used to move
unit across a roof. Level by using unit frame as reference.
See Fig. 1 for additional information. Unit weight is shown
in Tables 1A and 1B. These units are not designed for han-
dling by forklift trucks.
Roof Curb — Assemble and install as described in in-
structions shipped with this accessory. Accessory roof curb
and information required to field fabricate a roof curb is shown
in Fig. 2A and 2B. Install insulation cant strips, roofing, and
counter flashing as required. For unit drains to function prop-
erly, curb must be level or within tolerances shown in
Fig. 2A and 2B.
Roof Mount — Check building codes for weight distri-
bution requirements. Unit weight is shown in Tables 1A
and 1B.
Slab Mount — Provide a level concrete slab that ex-
tends beyond unit cabinet at least 6 inches. Make a slab
8 in. thick with 4 in. above grade. (For condensate drain to
function properly, slab must be at least 4 in. above grade.)
Use gravel apron in front of condenser coil air inlet to pre-
vent grass and foliage from obstructing airflow.
2