After 260K miles the PSE pump that controls the door locks and provides vacuum to the AC vacuum pods when REST is selected on the AC control panel finally started to die.

It would lock the doors promptly and shut off, but when unlocking; the pump ran a good 30 seconds after everything was unlocked. I didn't know if there was an issue with the pump motor or the vacuum manifold works, but I knew it was due to be swapped out with a newer pump.

I did diagnose the 3 pump lines (yellow, clear and yellow mixed) for leaks, but everything held vacuum and pressure. Over the years my main clear line that runs from the pump to the vacuum distributor block on the firewall disintegrated into many sections requiring a new line be run. I also replaced/rebuilt/inspected as many of the vacuum pods on the AC stack (maybe 11 altogether) when I replaced the evaporator and heater cores.

The pump motor just wouldn't blow as well as it sucked.

New pumps are available, but cost a bunch of money. So it was time to hit eBay for a domestic pump that most likely didn't endure 260K miles and the minor issues that my original had to put up with. A seemingly good used pump showed up at my house for $170. The outer case was a bit chewed during removal from the donor car, but I would just reuse my case and just swap out the innards.

Not everything has to come out of the trunk, but I took out the battery cover, trunk mat, wind screen, wind screen cover and backrest. I then removed the black outer rectangle box just outside of the pump which reveals a hidden 8mm screw that retains the white K2 box just above the pump. With the K2 box removed, the PSE pump lifts up out of its carrier and flops onto the spare tire hatch cover. Carefully, remove the foam insulator from the outside of the pump. You will have to reuse the insulation so take your time, it is slightly glued to the PSE case in several spots.

I use a 5/16 ths by 1/4 inch Craftsman open end wrench to remove all my vacuum fittings. You just slip the 5/16th end between the fitting and the case and lift. Very simple. With all three fitting popped, you just have to pull to the side while lifting the 2 method electrical connector. Now the pump if fully free of the car.

There are 2 small screws at the top of the case and a bunch of snap locks on the bottom. I used 2 thin blade flat screwdrivers and a knife to slowly release the locks. I started on one end and then released the locks on one side and the other end. Work slowly and don't damage anything.

When the white bottom pops off the sort of heavy pump motor and electronics are ready to fall out,

My old pump (pictured) was loaded with black residue from 23 years of service and smelled a little burnt. The newer pump didn't have a 10th the residue and nothing other than a normal electrical component odor. Peering in the top of the old motor, I did notice that the 2 carbon brush arms were closer to the armature than on the eBay motor.

 

Interesting.
My central locking system is okay except my trunk takes 15 secs to unlock

 

With the trunk open, lock and unlock the car using the remote on one of the doors.

Listen for the pump operation at the right side of the trunk. It takes vacuum to lock the car and pressure to unlock. After each operation the pump should immediately stop. If it doesn't, then you have to figure out if it's a vacuum pod, vacuum line, vacuum distributor, or the pump itself. The vacuum pod for the trunk lock is a little rare. When mine went out 6 months ago, the only one I could find came from old stock at a dealership in Egypt. You have a different year car than mine, so it might be a different vacuum pod.

Either way, if you have a leaky vacuum system, the pump tries too hard to do it's job and eventually fails.

On a side note, I think the vacuum pump tries to assist the engine vacuum reservoir during acceleration and a weak PSE on an otherwise good system will enable the center vent to stop blowing when the AC is on. So far, with the newer pump, this nagging issue hasn't recurred. Fingers crossed.