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2. Drive motor reverses but does not forward, blower motor runs
A. If computer dot (first dot on the left) does not come on replace the computer.
B. Check for voltage across the coil of the forward contactor located in the reversing panel box. The
contactor according to your diagram is marked CR2. The coil markings A1 and A2.
If voltage is present, replace reversing contactor.
If voltage is not present, there is a bad wire or termination between BS2 and contactor coil (CR2).
C. If there is voltage across the two AS2 terminals and no voltage across the two BS2 terminals,
replace the arc suppressor board.
If there is no voltage across the two AS2 terminals on the arc suppressor board, the problem is a bad
wire or termination between the AS2 board and the J7 9-pin computer connector no. 8 or faulty
computer.
3. Drive motor works in forward mode but does not reverse, blower motor runs
A. If computer dot (second one from left) does not come on, check program to see if set for reverse.
B. If set for reverse, replace computer.
C. Check for voltage across the coil of the reversing contactor located in the rear panel box. The
contactor according to your diagram is CR3, also the markings on the coil are A1 and A2.
If there is voltage, replace the coil or the complete contactor.
If there is no voltage, check for voltage across the two BS3 terminals on the arc suppressor board.
If there is voltage across the two BS3 terminals and no voltage across the coil of the reversing
contactor (A1 and A2), the problem is bad wires or terminations between BS1 and the contactor
coil.
D. If there is no voltage between the two BS3 terminals on the arc suppressor board, check for
voltage across the two AS3 terminals on the board.
If there is voltage across the two AS3 terminals and no voltage across the two BS3 terminals,
replace the arc suppressor board.
If there is no voltage across the two AS3 terminals, the problem is bad wires or terminations
between the arc suppressor board and the computer 9-pin connector no. 9 or a faulty computer.
4. Blower motor does not operate, drive motor runs
A. Check for voltage across terminals A1 and A2 of the impeller contactor. This is the single contactor
in the reversing control box.
If voltage is present check for voltage across the blower motor. If there is voltage at the blower
motor replace the motor.
If there is no voltage at the blower motor, the problem is bad wires or terminations between the
contactor and the motor.
B. If there is no voltage present at A1 and A2 of the contactor, check for voltage across the two BS1
terminals of the arc suppressor board.