Carrier 69NT40-541-001 Operation And Service page 57

CODE # TITLE
Cd30 In-Range Tolerance
Stagger Start Offset
Cd31
Time (Seconds)
Current Limit
Cd32
(Amperes)
Perishable Mode
Dehumidification/
Cd33
Humidification
Control (% RH)
Economy Mode
Cd34
(On-Off)
Cd35 Bulb Mode
Evaporator Speed
Cd36
Select
Table 4–5 Controller Function Codes (Continued)
The in-range tolerance will determine the band of temperatures around the set
point which will be designated as in-range. If the control temperature is in-range,
the in-range light will be illuminated. There are four possible values:
1 = ±0.5°C (±0.9°F)
2 = ±1.0°C (±1.8°F)
3 = ±1.5°C (±2.7°F)
4 = ±2.0°C (±3.6°F) - Factory Default
The stagger start offset time is the amount of time that the unit will delay at start-
up, thus allowing multiple units to stagger their control initiation when all units are
powered up together. The eight possible offset values are:
0 (Factory Default), 3, 6, 9, 12, 15, 18, or 21 seconds
The current limit is the maximum current draw allowed on any phase at any time.
Limiting the unit's current reduces the load on the main power supply. This is ac-
complished by reducing the SMV position until current draw is reduced to the set
point. When desirable, the limit can be lowered. Note, however, that capacity is
also reduced. The five values for 460vac operation are:
15, 17, 19, 21 (Factory Default), 23
Relative humidity set point is available only on units configured for dehumidifica-
tion. When the mode is activated, the control probe LED flashes on and off every
second to alert the user. If not configured, the mode is permanently deactivated
and "-----" will display. The value can be set to "OFF." "TEST," or a range of 65
to 95% relative humidity in increments of 1%. [If bulb mode is active (code Cd35)
and "Lo" speed evaporator motors are selected (code Cd36) then set point rang-
es from 60 to 95%.] When "TEST" is selected or test set point is entered, the heat
LED should illuminate, indicating that dehumidification mode is activated. After
a period of five minutes in the "TEST" mode has elapsed, the previously selected
mode is reinstated.
If humidification (CnF35) is enabled, then humidification will be
enabled and dehumidification locked out at set points of 75% and
above. At set points be low 75%, dehumidification will be enabled
and dehumidification locked out.
Economy mode is a user selectable mode of operation provided for power sav-
ing purposes.
Bulb mode is a user selectable mode of operation that is an extension of dehu-
midification control (Cd33). If dehumidification is set to "Off," code Cd35 will dis
play "Nor" and the user will be unable to change it. After a dehumidification set
point has been selected and entered for code Cd33, the user may then change
code Cd35 to "bulb." After bulb has been selected and entered, the user may
then utilize function codes Cd36 and Cd37 to make the desired changes.
This code is enabled only if in the dehumidification mode (code Cd33) and bulb
mode (Cd35) has been set to "bulb". If these conditions are not met, "alt" will be
displayed (indicating that the evaporator fans will alternate their speed) and the
display cannot be changed. If a dehumidification set point has been selected
along with bulb mode then "alt" may be selected for alternating speed, "Lo" for
low speed evaporator fan only, or "Hi" for high speed evaporator fan only. If a
setting other than "alt" has been selected and bulb mode is deactivated in any
manner, then selection reverts back to "alt."
4–21
DESCRIPTION
NOTE
T-316