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Hot Engine

  1. Ensure engine is at normal operating temperature. On Accord models, disconnect hose No. 14 from power valve control solenoid valve located within control box, and plug hose. See Fig 1 and Fig 2 .
  2. On Civic 1500 models, disconnect vacuum hose from power valve at carburetor and plug hose. See Figure . On Prelude models, disconnect hose No. 14 from control box No. 1 and plug hose. See Figure and Figure .
    Fig 1: Accord Control Box
    G42712
  3. On Civic 1500 models with manual transmission and without power steering, remove cover from control box No. 2. On all models, start engine and check that frequency solenoid valves A and B are operating while running engine at 2500 RPM.
    Fig 2: By-Passing Accord Vacuum Control Valve
    G42243
    NOTE: On Civic 1500 models equipped with automatic transmission and power steering, frequency solenoid valves are located outside of control box No. 2. Hose No. 6 leads to valve A and hose No. 21 leads to valve B.
  4. Frequency valves should emit a clicking sound. It may be easier to place hand on each individual valve to feel movement. If either solenoid A or B is inoperable, replace valve and retest. If both solenoid valves operate properly, proceed to step 6).
    Fig 3: Civic 1500 Control Boxes No. 1 & 2
    G42715
  5. If either solenoid A or B are inoperable, check for voltage at terminal lead wires while engine is running at 2500 RPM. If voltmeter fluctuates between 12 volts and zero volts, replace solenoid valves and retest.
  6. If voltmeter indicates 12 volts and engine operating condition is normal, check vacuum lines of system for blockage, leaks or disconnected hoses. If no problem exists, check both air control valves A and B.
  7. If voltmeter indicates zero volts, proceed to TROUBLE SHOOTING  . If voltmeter indicates 12 volts and engine operating condition is abnormal, or engine stops, proceed to TROUBLE SHOOTING  .
  8. Reconnect vacuum hoses. With A/C, radiator fan, heater blower motor, rear window defogger and headlights off, ensure that frequency solenoid valves are inoperable while engine is at idle speed.
  9. If solenoid valves are inoperable, system is okay and testing is complete. If solenoid valves do operate, proceed to TROUBLE SHOOTING  .
Fig 4: Prelude Control Boxes No. 1 & 2
G42716
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