Nilfisk-Advance SR 1900 Service Manual

Also see for 56508769: Instructions for use Instructions for use

Nilfisk-Advance SR 1900 Service Manual Manual pdf 10 page image

8 - FORM NO. 56043123 - SR 1900SECTION 4 — HEATING SYSTEMNote: Refer to Section 2 — Know Your Machine and the schematics in Section 6 — Appendix.GENERAL SYSTEM OVERVIEWThe SR 1900 cab heating system uses an electronic Heater Control Assembly (15) to direct the appropriate amount of engine coolant to the Heater Core (9) in theHeater Air Box Assembly (10). The Blower Assembly (8) in the Heater Air Box Assembly blows filtered air through the Heater Core to provide warm air to the cab.A four-port bypass butterfly valve in the Heater Control Assembly, run by a small electric motor, controls the coolant flow to the Heater Core. The HeaterTemperature Control (4) in the cab controls the voltage to the valve motor, and uses a feedback potentiometer to sense the position of the butterfly valve.ELECTRICAL CIRCUIT OVERVIEWHeater Blower MotorThe following conditions must be met for the blower motor to function:Positive (+) VoltageThe key switch (S1)must be in either the accessory or ignition position to provide +12 VDC (GRN/BLU wire) to the 20A circuit breaker CB4.Circuit breaker CB4 must be closed to provide +12 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 input load side of the HVAC Relay K8.HVAC Relay K8 must be closed to provide +12 VDC (VIO/GRAY wire) to the positive terminal on the Fan Switch S30.The Fan Switch S30 must be set to the Low (YEL wire), Medium (RED wire) or High (ORN wire) position to provide +12 VDC to the corresponding terminal onthe Blower Motor M6.Negative (–) VoltageThe Blower Motor M6 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).Heater Temperature ControlThe following conditions must be met for the heater temperature control to function:Positive (+) VoltageThe key switch must be in either the accessory or ignition position to provide +12 VDC (GRN/BLU wire) to the 20A circuit breaker CB4.Circuit breaker CB4 must be closed to provide +12 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 input load side of the HVAC Relay K8.HVAC Relay K8 must be closed to provide +12 VDC (VIO/GRAY to RED wire) to the Heater Temperature Control E1.Negative (–) VoltageThe Heater Temperature Control E1 (BLK wire) must be connected to battery ground.The control side (coil) of the HVAC Relay K8 must be connected to battery negative (BLK wire).