Nilfisk-Advance 56508769, Service Manual

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14 - FORM NO. 56043123 - SR 1900
CONDENSER FAN, THERMOSTAT, PRESSURE SWITCH AND COMPRESSOR MOTOR
The following conditions must be met for the air conditioning system to function:
Positive (+) Voltage
The key switch must be in either the accessory or ignition position to p12 VDC (GRN/BLU wire) to the 20A circuit breaker

CB4 .
Circuit breaker

CB4 must be closed to p12 VDC (VIO wire) to the control side (coil) of the HVAC Relay K8 .
The 20A circuit breaker

CB9 must be closed to provide voltage (RED/VIO wire) to the load side of the HVAC Relay K8 .
HVAC Relay

K8 must be closed to p12 VDC (VIO/GRA wire) to the positive terminal on the Fan Switch S30 .
The Fan Switch

S30 must be set to the Low, Medium or High position to p12 VDC (RED/WHT wire) to the AC Switch S35 .
The AC Switch

S35 must be closed to p12 VDC to:
The control side (coil) of the Condenser Fan Relay
o
K9 (WHT wire).
The input terminal on the Thermostat
o
S33 (BLK/WHT wire).
The Thermostat

S33 (normally closed) must be closed to p12 VDC (GRN wire) to the input terminal on the Pressure Switch S34 .
The Binary Pressure Switch

S34 (normally closed) must be closed to p12 VDC (GRN/WHT wire) to the load side of the Compressor Relay K10
(terminal 30 ).
The load side of the Compressor Relay

K10 (normally closed) must be closed to p12 VDC (BLU/BRN wire from terminal 87a ) to the Compressor
Hydraulic Valve L10 .
Note: The Compressor Relay K10 coil (control side) is wired in parallel with the Hopper Up/Down Hydraulic Valve L5 . When the Raise Hopper switch is pressed,
it actuates the Hopper Up/Down Hydraulic Valve L5 to raise the hopper, and actuates the Compressor Relay K10 coil to open the circuit to the Compressor
Hydraulic Valve L10 and switch off the A/C compressor motor. This feature allows the machine to use the maximum available hydraulic force to raise the hopper.
Negative (–) Voltage
The control side (coil) of the Condenser Fan Relay K9 must be connected to battery negative (BLK wire).

The control side (coil) of the Compressor Hydraulic Valve L10 must be connected to battery negative (BLK wire).

The control side (coil) of the HVAC Relay

K8 must be connected to battery negative (BLK wire).