Programmable Functions Q3 and Qht Controls for Direct Expansion Systems
12 L-2516 ENGLISH
19: Cool-Only Mode
(Factory Default: HP)
You can select Heat Pump or Cool-Only operation. Select “HP” and the unit will operate in the default Heat Pump Mode, which
allows for cooling, reverse cycle heating and (optional) electric heat modes. Select “CL” for cool-only operation and the unit will
operate in Cooling or (optional) electric heat modes.
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20: High Pressure Delay
(Factory Default: 3 minutes)
This function is used when the standard 3-minute delay during the high pressure fault routine requires an extended delay. The
delay can be increased up to 5 minutes between high-pressure-fault off cycles.
21: Anti-Icing Routine Adjustment
(Factory Default: 70°F)
The anti-icing routine prevents ice build up on the evaporator coil during extended periods of cooling operation. Installation
variables such as grille sizes, length of ducting, insulation, and ambient temperatures determine the run time required to
achieve set point. Factors that substantially increase run time include operating the system with hatches and doors open, and
programming an unrealistic set point (e.g. 65°F/18.3°C). Such situations can cause the evaporator to form ice on warm humid
days.
This function is used during cooling operation to allow any ice that may have formed on the evaporator coil to melt when the
cabin temperature drops below 70°F (default). This routine works in 10-minute cycles during which time the compressor cycles
off for 15 seconds for each degree the ambient-temperature is below 70°F (default) and runs during the rest of the 10-minute
cycle. For example, if the inside temperature is 67°F, the compressor will shut off for 45 seconds (3 x 15 seconds), and then run
for nine minutes and 15 seconds (10 minutes minus 45 seconds), repeating in 10-minute intervals. You may adjust the cabin
temperature at which the Anti-Icing routine is initiated. The range of adjustment is 65°F to 80°F.
22: Fan Speed Division
(Factory Default: 5)
You can select either 5 or 3 fan-speed divisions based on the Fan Response Differential (see Programmable Function “4: Fan
Response Differential” on page 9). The default is set at 5 fan-speed divisions.
• Q3 - Displays either the individual High, Medium and Low fan-speed LEDs if 3 speeds are selected, or a combination
of the High, Medium and Low fan-speed LEDs if 5 speeds are selected, for example:
• Low Speed = Low LED
• Medium Low Speed= Medium and Low LEDs
• Medium Speed = Medium LED
• Medium High Speed = Medium and High LEDs
• High Speed = High LED
• Qht - Displays 5 bars to indicate the five distinct speed changes or groups the bars to show three distinct speed
changes.
23: Aux Heat Enabled/Disabled
(Factory Default: “- -” Disabled)
The control allows operation of an optional auxiliary (aux) electric heater. The default for this feature is “- -” indicating disabled.
If an aux heater upgrade kit is installed, change this setting to “h1”. Selecting “h1” allows the electric heater to be operated
independently of the reverse-cycle heating and never at the same time.
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NOTE
If you select “CL” Cool-Only mode, a 2-minute compressor delay will initiate whenever the compressor shuts down on
set point, a fault, or a power outage. The two minute delay will begin immediately after compressor shuts down. The
display will show the remaining time delay countdown at two second intervals when compressor is called to operate
within the two minute countdown period. If the two minute delay period has passed before the compressor is called to
operate, the compressor will come on with no delay.
NOTE
If you enable the aux heat function (“h1”), the fan will delay turning off for 30 seconds to allow the electric heater to
cool down. The delay occurs when the electric heater cycles off after set point is reached or when the mode is
changed.
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