Air Suspension: Location Of Compressor And Computer/controller

[Chip L]

1990 LS400 - 250k mi - Air Suspension

Looking for specific location of air suspension compressor and A/S computer/controller.

Suspension operates OK for days or weeks, then the rear totally drops. Both rear sides drop in tandem - one is not lower than the other. When the rear drops, the height indicator on the dash remains constant (if I'm in Hi mode, will read HI despite switching to NORMAL).

I don't believe the entire suspension is totally shot. 1) The front never drops. 2) The rear will function OK for weeks. 3) One side is not never lower than the other.

When the rear does drop after parking, I can hear a hissing from the driver rear well.

I'm thinking the problem may be a computer/controller issue or an air line / air release/bleeder valve issue. I'm open to ideas.

Thx

Chip L