The
Cooling capacity reduction by modulation is the same as described for the conventional operating mode when any of the above first four conditions (1. thru 4.) are invalid.
With set points below
c.Operation in the economy mode (Code 34 set to ON)
The economy mode selection determines the status of the economy mode of operation. There are two values: “ON” and “OFF.” A code which represents the status of this function is recorded in the DataCorder memory whenever the value is changed.
Economy mode is a user selectable mode of operation provided for power saving purposes. Economy mode could be utilized in the transportation of temperature tolerant cargo or
The economy mode is activated by selecting function code Cd34 to the “ON” status. There is no active display indicator that economy mode has been activated, and a manual display of Cd34 is a way to be sure if the economy mode is or is not active.
In order to achieve economy mode perishable operation, a perishable set point must be selected PRIOR to activating economy mode. When economy mode perishable is active, the evaporator fans will be controlled as follows: At the start of each cooling or heating cycle, the high speed evaporator fans will be run for three minutes. After that initial three minutes, the evaporator fans will be switched to low speed any time the supply air temperature is within ¦ 0.25_C (0.45_F) of the set point and the return air temperature is less than or equal to the supply air temperature + 3_C (5.4_F). When the fans switch to low speed, they will run in low speed for one hour. At the end of the hour, the evaporator fans will switch back to high speed. The evaporator fans will again run in high speed for three
minutes and the above mentioned cycle will be repeated, just as it was from the start of the cooling or heating cycle. If the unit is not equipped with dual speed evaporator fans, then economy mode perishable will perform exactly the same as the normal control mode.
d.Operation in bulb mode (Code 35 set to bulb and Code 33 selected)
Bulb mode is an extension of the dehumidification mode. Dehumidification must be enabled by selecting a value (percentage of relative humidity) at function code Cd33 before bulb mode function code Cd35 can be initiated.
To initiate bulb mode, use the ARROW keys to scroll to function code Cd35 and change from “Nor” to “bulb.” Once the bulb mode is activated, the user may then change from the normal evaporator fan operation where the fan speed alternates every hour between low or high speed operation. This is done by toggling function code Cd36 from its default of “alt” to “Lo” or “Hi” respectively. If low speed evaporator fan operation is selected, this gives the user the additional capability of selecting dehumidification set points from 60 to 95% (instead of the normal 65 to 95%).
In addition, if bulb mode is active, the user is given the option to change the defrost termination sensor (DTS) temperature, in which defrost is terminated from the normal 25.6_C (78_F) temperature setting to 4_C (39.2_F) in 0.1_C (0.2_F) increments. The temperature set point that the DTS temperature must go below before the defrost interval timer begins counting down also changes from 0_C to 10_C as the desired DTS termination temperature is raised.
Bulb mode is terminated when:
SCode Cd35 is set to “Nor.”
SCode Cd33 for dehumidification is set to “Off.”
SThe user changes the set point to one that is in the frozen range.
When bulb mode is disabled by any of the above means, the evaporator fan operation for dehumidification reverts to “alt” and the DTS termination setting resets to the normal 25.6_C (78_F).
