Cooling System: Testing and Inspection

For wiring diagram information, refer to Cooling System/Diagrams.

Accord & Prelude w/Carbureted Engine

1. Start engine and run until it reaches normal operating temperature.
2. Monitor coolant temperature using suitable thermometer and observe cooling fan operation.
3. Cooling fan should begin to operate when coolant temperature reaches approximately 191-197°F, and fan should stop running when coolant temperature drops to approximately 182-188°F.
4. If fan fails to operate, proceed as follows:
a. Stop engine, disconnect electrical connector to thermo sensor, connect suitable jumper between connector terminals, then turn on ignition switch.
b. If fan operates, replace thermo sensor and recheck system operation.
c. If fan fails to operate, check for blown fuse, defective relay, damaged or disconnected wiring or defective fan motor.
5. On models with A/C, place control in maximum cooling position.
6. On models with A/C, if cooling fan does not operate when compressor clutch is engaged, check for open circuit between fan relay and A/C switch, defective switch or defective compressor clutch diode.

Accord & Prelude w/Fuel Injected Engine

1. Start engine and run until it reaches normal operating temperature.
2. Monitor coolant temperature using suitable thermometer and observe cooling fan operation.
3. Cooling fan should begin to operate when coolant temperature reaches approximately 191-197°F and fan should stop running when coolant temperature drops to approximately 182-188°F. When coolant temperature is above approximately 220°F, the condenser fan goes into operation until coolant temperature drops to approximately 214°F.
4. On models with A/C, place control in maximum cooling position. Cooling fan should run whenever A/C compressor clutch is engaged.
5. On all models, using suitable gauge to monitor underhood temperature, stop engine and listen for cooling fan operation.
6. With engine stopped and underhood temperature above 220°F, cooling fan should run for a maximum of 10 minutes or until temperature drops below 220°F.
7. If system fails to operate as outlined, inspect fan circuit for blown fuses, loose connections and damaged wiring, and repair as needed.
8. If fan circuit wiring is satisfactory, test components individually and replace as needed. If all other components are satisfactory but system still does not perform as outlined, replace timer module and recheck system operation. Do not attempt to perform resistance measurements between module terminals as timer module may be damaged.

Civic & CRX w/Fuel Injected Engine

1. Start engine and run until it reaches normal operating temperature.
2. Monitor coolant temperature using suitable thermometer and observe cooling fan operation.
3. Cooling fan should begin to operate when coolant temperature reaches approximately 191-197°F, and fan should stop running when coolant temperature drops to approximately 182-188°F.
4. If fan fails to operate, proceed as follows:
a. Stop engine, disconnect electrical connector to thermo sensor, connect suitable jumper between connector terminals, then turn on ignition switch.
b. If fan operates, replace thermo sensor and recheck system operation.
c. If fan fails to operate, check for blown fuse, defective relay, damaged or disconnected wiring or defective fan motor.
5. On models with A/C, place control in maximum cooling position.
6. On models with A/C, if cooling fan does not operate when compressor clutch is engaged, check for open circuit between fan relay and A/C switch, defective switch or defective compressor clutch diode.