THERMO Valve & Purge Control Valve
- Ensure vacuum lines are properly routed and are not damaged or obstructed. With engine coolant temperature below a designated thermosensor operating temperature, disconnect upper vacuum hose from purge control valve. Refer to THERMO SENSOR OPERATING TEMPERATURE table for specific temperature.
- Connect vacuum gauge to hose. Start engine and let idle. Vacuum should not be present. If there is vacuum on EFI Civic models, test purge cut-off solenoid valve. See PURGE CUT-OFF SOLENOID VALVE
test. If there is vacuum on all other models, replace thermo valve. Retest thermo valve.THERMO SENSOR OPERATING TEMPERATURE
Application Operating Temperature °F (°C) Accord 131 (55) Civic 1.3L 122 (50) 1.5L Carbureted Engine 104 (40) EFI Engine 149 (65) Civic CRXSi 149 (65) Prelude Carbureted Engine 158 (70) EFI Engine 131 (55) - On all models, if there is no vacuum, remove vacuum gauge and reconnect hose. With engine coolant temperature above specified temperature, disconnect upper vacuum hose from purge control valve. Run engine at idle and observe vacuum gauge. On EFI Civic models, vacuum should be present, after 5 seconds of operation.
- If there is no vacuum on EFI Civic models, test purge cut-off solenoid valve. See PURGE CUT-OFF SOLENOID VALVE test. If there is no vacuum on EFI Accord or EFI Prelude models, replace thermo valve and retest.