Blower Control (A54)
BLOWER CONTROL (A54)
16−PIN PLUG |
(BOARD TO MOTOR) |
DIAGNOSTIC |
LED |
ADJUST
SELECTOR PINS
(Setting affects both heating and cooling modes)
HEATING SPEED SELECTOR PINS
COOLING SPEED SELECTOR PINS
Figure 12
!WARNING
Electric shock hazard. Can cause injury or death. Before attempting to perform any service or maintenance, turn the electrical power to unit OFF at disconnect switch(es). Unit may have multiple power supplies.
15GCSX units are equipped with a variable speed motor that is capable of maintaining a specified CFM throughout the external static range. A particular CFM can be obtained by positioning jumpers (COOL, HEAT, and ADJUST) on the blower control. The HEAT and COOL jumpers are labeled A, B, C and D. Each of the numbers corresponds with an air volume (CFM) setting. The ADJUST jumper is labeled Test, −, +, and Norm. The + and − pin settings are used to add or subtract a percentage of the CFM selected. The Test jumper is used to operate the motor in the test mode. See figure 12.
Factory settings for the blower speed jumpers are given in the wiring diagram in figure 11. Figure 12 shows the blower control. Use tables 4, 5 and 6 to determine the correct air volume for operation in heat and cool mode.
The CFM LED located on the blower control flashes one time per 100 cfm to indicate selected blower speed. For example, if the unit is operating at 1000 CFM, CFM LED will flash 10 times. If the CFM is 1150, CFM LED will flash 11 full times plus one fast or half flash.
At times the light may appear to flicker or glow. This takes place when the control is communicating with the motor between cycles. This is normal operation.
Read through the jumper settings section before adjusting the jumper to obtain the appropriate blower speed.
To change jumper positions, gently pull the jumper off the pins and place it on the desired set of pins. The following section outlines the different jumper selections available and conditions associated with each one. Refer to figure 12.
After the CFM for each application has been determined, the jumper settings must be adjusted to reflect those given in tables 4, 5 and 6. From the tables, determine which row most closely matches the desired CFM. Once a specific row has been chosen (+, NORMAL, or −), CFM volumes from other rows cannot be used. Below are descriptions of the jumper selections.
The variable speed motor slowly ramps up to and down from the selected air flow during both cooling and heating demand. This minimizes noise and eliminates the initial blast of air when the blower is initially energized.
ADJUST
The ADJUST pins allow the motor to run at normal speed, approximately 15 percent higher, or approximately 15 percent lower than normal speed. Tables 4, 5 and 6 give three rows (+, NORMAL, and −) with their respective CFM volumes. Notice that the normal adjustment setting for heat speed position C in table 4 is 900 CFM. The + adjustment setting for that position is 1035 CFM and for the − adjustment setting is 765 CFM. After the adjustment setting has been determined, choose the remaining speed settings from those offered in the table in that row.
The TEST pin is available to bypass the blower control and run the motor at approximately 70 percent to make sure that the motor is operational. This is used mainly in troubleshooting. The G terminal must be energized for the motor to run.
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