Compressor relay change - Navigator & Expeditions built after FEB. 3, 2003
Navigator vehicles built prior to February 3, 2003 use a solid-state relay for the air suspension compressor motor. The control line from the module is grounded to energize the relay. The relay is located on the radiator support on the right side just behind the headlamp assembly.
Both Navigator and Expedition vehicles equipped with air suspension built since February 3, 2003 utilize a mechanical relay for the compressor motor. The control line from the module is grounded to energize the relay. The relay is located on the compressor bracket just above the compressor attachment to the radiator support on the right side.
In addition, there are important wiring differences between the two relays. Early production vehicle relays have one power feed, where late production relays have two (both are hot at all times). The solid-state relay also employs an external full-time ground, where the mechanical relay does not.
Relay Location on a 1993-1998 Mark VIII
The air suspension compressor relay is located inside the passenger side front fender. 1st Gen's have the relay closer to the RF wheel, while the 2nd Gen's are on the "front side", further away from wheel.