Vacuum Exhaust Heat Control Valve: Testing
- Visually inspect VHC for damage, repair or replace as necessary. Check that vacuum source is working. If a vacuum check valve is used, it must be checked for proper operation.
- Using a hand operated vacuum source, apply specified vacuum to VHC vacuum motor and hold for one minute. See VHC VACUUM SPECIFICATIONS table.
- VHC butterfly valve must start to close and be completely closed when specified vacuum is applied. Vacuum motor must not leak more than 2 in. Hg vacuum when 15 in. Hg vacuum is applied.
- VHC butterfly valve must return to full open position when vacuum is released.NOTE: VHC butterfly valve is closed if the shaft lever comes within 0.065" of the stop.VHC VACUUM SPECIFICATIONS
Engine Start Closing (in. Hg) Closed (in. Hg) 302" 1-3 6 or less 351 W" 1-3 6 or less All Others 3-6 10 or less