DESCRIPTION

Both the heating-A/C system and the heater-only system use two vacuum check valves. One vacuum check valve (1) is installed in the accessory vacuum supply line located on the dash panel in the engine compartment, near the brake booster and, the other check valve is located on the passenger side of the HVAC housing, behind the glove box. The vacuum check valves are used to stabilize the vacuum within the HVAC vacuum circuits whenever the vehicle is accelerating or when engine vacuum varies due to operating conditions. The vacuum check valves are designed to allow vacuum to flow in only one direction (2) through the vacuum supply circuits.