Air Control Diaphragm & Valve
- In warm weather, it may be difficult to find a malfunction in hot air control system. In cold weather, vacuum leaks or faulty air control valve will result in engine stalling or hesitation, increased fuel consumption and/or lack of power.
- Check vacuum hoses for cracks and proper connections. Inspect air control diaphragm (vacuum motor) with engine stopped. See Fig 1 .
- Disconnect vacuum hose from air control diaphragm. Apply vacuum to diaphragm. Valve should rise to open position (hot air inlet uncovered, fresh air inlet blocked).
- If diaphragm does not hold vacuum, replace it. With valve in open position, pinch hose to trap vacuum. Valve should remain open for at least 30 seconds. If valve closes too soon, replace air control diaphragm.
NOTE:
Engine must be cold before performing following test. Check hoses, air control diaphragm and valve first.