Slide the tube nut wrench over the brake line to the master cylinder connection. The master cylinder is normally on the driver's side of the engine bay and mounted on the firewall. Orient the wrench so that it fits over the tube nut on the end of the brake line.
2Disconnect the brake line. Turn the nut counterclockwise to remove. Note the location of each brake line. There are four lines total, and they need to be put back in the same location when reinstalling the lines. You may want to mark them with masking tape and permanent marker.
3Unplug the master cylinder cap electrical plug.
4Remove the brake master cylinder to brake booster bolts with a socket wrench.
5Back the master cylinder off the brake booster.
6Unbolt the bolts holding the brake booster to the firewall on your vehicle.
7Pull the cotter pin out of the brake pedal to brake booster connecting pin with a pair of pliers. This is done inside the vehicle down in the driver side foot well.
8Pull the brake pedal to brake booster connecting pin out to disconnect the brake pedal from the brake booster connecting arm.
9Mark and remove the vacuum hoses on the brake booster and slide the booster off the firewall.
10Install the new brake booster. Installation is the reverse of removal
one thing you can try is to take out the fuse for the door ajar button . this will take it off for sure. you can even try putting it back to see if it may reset
I suspect it is partially obscured from visibility by a bracket on the passenger side of the firewall. The low pressure port is actually on the receiver/dryer below this bracket. See the link for a video on how to get to it. (It's for a Ford Expedition, but is probably the same on your Mark).
Charging the AC on 1997 2002 Ford Expedtion F150
it is located at side of dash drivers side page 109 of your owners manual starts your fuse information the following link is the owners manual incase yours is unavailable
1998 Lincoln Mark VIII Owner Guide 1st Printing
There are several things that can cause these to fail in addition to a fuse. You need specialist knowledge to trace out the circuit and identify if it is the switches, power supply, wiring or control circuits. I suggest you take it to your local repairer or an auto electrician. I presume you have checked that the lock out switch is not on.
First make sure to check all air conditioning component. A basic a/c gauge and test light is needed to help diagnose most air conditioner problems. Normally internal system moisture is a leading cause of air conditioner system failure. All air conditioning parts are available at http://www.1airconditioning.com/air_conditioning_parts.htm This helps to solve your problem.
If the engine seems to be running well, the problem is not likely with the thermostat, but with the blend door in the heater control box. These have a tendency to get stuck over time. To see if the have the potential for heat, warm the engine up to normal temperature. Then under the hood, find the heater hoses. They are smaller diameter hoses (about one inch in diameter). There are two of them one runs to the heater core, the other is the return line fell both hoses. If they are warm to the touch (almost hot), then you have coolant thru the core. If only one side is hot, then you may have a clogged heater core. If there is heat on both, the problem is in either the dash controls for the heat, of the blend box under the dash.