Controls, Operation,
and Troubleshooting
CONTENTS
Page
INTRODUCTION
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
VAV Control System
. . . . . . . . . . . . . . . . . . . . . . . . . . 2
Processor Board
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
• P1 — LEAVING-AIR SET POINT
• P2 — ECONOMIZER POSITION
• P3 — RESET LIMIT
• P4 — DEMAND LIMIT
• P5 — ECONOMIZER MINIMUM POSITION
• P6 — WARM-UP SET POINT
• P7 — RESET TEMPERATURE
• PROCESSOR BOARD OUTPUTS
• CONFIGURATION HEADER AND DIP SWITCH
ASSEMBLY
Relay Board
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Display Board
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermistors
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
• T1 — LEAVING-AIR SET POINT THERMISTOR
• T2 — RETURN-AIR THERMISTOR
• T3 — SATURATED CONDENSING
TEMPERATURE, CIRCUIT 1
• T4 — SATURATED CONDENSING
TEMPERATURE, CIRCUIT 2
• T10 — RESET TEMPERATURE
Compressor Operation
. . . . . . . . . . . . . . . . . . . . . . . 7
• CONTROL RELAY (CR)
Accessory Board
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
• P3 — RESET LIMIT
• P5 — ECONOMIZER MINIMUM POSITION
• P6 — MORNING WARM-UP TEMPERATURE
Single-Step Demand Unit
. . . . . . . . . . . . . . . . . . . . 12
Demand Limit Control Module (DLCM)
. . . . . . . 12
OPERATING INFORMATION
. . . . . . . . . . . . . . . . 12-21
Digital Display
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
• CODES 0 THROUGH 6, CAPACITY STEPS
• CODES 20 THROUGH 30 AND 88, OPERATIONAL
STATUS
• CODES 51 THROUGH 87, OVERLOAD
INFORMATION
Operating Sequence
. . . . . . . . . . . . . . . . . . . . . . . . 13
• SIZE 024-034 AND 054-074 UNITS
• SIZE 044 UNITS
Head Pressure Control
. . . . . . . . . . . . . . . . . . . . . . 14
• SIZE 024-030 UNITS
• SIZE 034-074 UNITS
Inlet Guide Vanes
. . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Temperature Reset
. . . . . . . . . . . . . . . . . . . . . . . . . . 14
Demand Limit Control
. . . . . . . . . . . . . . . . . . . . . . . 17
Building Pressurization Mode
. . . . . . . . . . . . . . . . 17
Smoke Purge Mode
. . . . . . . . . . . . . . . . . . . . . . . . . 17
Units Equipped with Static Pressure Control
Option
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Page
Quick Test Program
. . . . . . . . . . . . . . . . . . . . . . . . . 17
SERVICE AND TROUBLESHOOTING
. . . . . . . . 21-32
Inlet Guide Vane Motor (Units with Inlet Guide
Vanes and Static Pressure Control Option)
. . 21
Modulating Power Exhaust Differential
Pressure Switch
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
• SIZE 024-030 UNITS
• SIZE 034,044 UNITS
• SIZE 054-074 UNITS
Inlet Guide Vane Differential Pressure Switch
(Units with Inlet Guide Vane and Static
Pressure Control Option)
. . . . . . . . . . . . . . . . . . . 21
• SIZE 024-030 UNITS
• SIZE 034,044 UNITS
• SIZE 054-074 UNITS
Differential Pressure Switch Set Point and Null
Span (Units Equipped with Inlet Guide Vane
and Static Pressure Control Option)
. . . . . . . . 22
Differential Pressure Switch Set Point and Null
Span (Units Equipped with Modulating Power
Exhaust Option)
. . . . . . . . . . . . . . . . . . . . . . . . . . . 23
VAV Diagnostic Information
. . . . . . . . . . . . . . . . . . 23
• CODES 51 AND 55: COMPRESSOR FAILURE
• CODES 59 AND 60: LOW-PRESSURE SWITCH
• CODES 63 AND 64: OIL PRESSURE SWITCH
• CODE 70: ILLEGAL UNIT CONFIGURATION
• CODES 71 TO 76: THERMISTOR/RESISTOR
FAILURE
• CODE 81: RESET THERMISTOR OR
POTENTIOMETER FAILURE
• CODE 82: SUPPLY-AIR TEMPERATURE SET POINT
POTENTIOMETER FAILURE
• CODE 83: ECONOMIZER FEEDBACK
POTENTIOMETER FAILURE
• CODE 84: RESET LIMIT POTENTIOMETER
FAILURE
• CODE 85: DEMAND LIMIT POTENTIOMETER (P4)
FAILURE
• CODE 86: MINIMUM POSITION ECONOMIZER
POTENTIOMETER FAILURE
• CODE 87: WARM-UP TEMPERATURE SET POINT
FAILURE
Electronic Controls Checkout
. . . . . . . . . . . . . . . . 25
• PROCESSOR BOARD CHECKOUT
• RELAY BOARD TROUBLESHOOTING
• DISPLAY BOARD CHECKOUT
• ACCESSORY BOARD CHECKOUT
• TWO-STEP DEMAND LIMIT CONTROL MODULE
(DLCM) TROUBLESHOOTING
Thermistor Troubleshooting
. . . . . . . . . . . . . . . . . 29
Control Wiring
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
48DK024-074
50DK,DY024-074
Variable-Air Volume Rooftop Units
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1
1
Tab
1a 1b
PC 111
Catalog No. 564-878
Printed in U.S.A.
48/50DK,DY-1T
Pg 1
4-96
Replaces: New
