I just joined this forum, as I'm the proud, new owner of a 2007 Sig Limited w/ moonroof. Dark Cherry Metallic. Wanted to comment that you, sir, are an outstanding writer. I thoroughly enjoyed this read. Bravo!A few things.
This is not particular to the Town Car, but something that is often overlooked and a good indicator of neglect. Just lift the oil-filler cap off of the engine while the car is off and look at the inside of the cap itself. If it has a buildup that has the consistency of axle grease, it is an indication of long oil-change intervals or shoddy oil in general. It can sometimes be caused by a malfunctioning PCV system, but why gamble?
It's a sad fact of life but one that humanity has endured with a persevering attitude since before history: power window cables wear and snap. The first sign of a cable that is bound by a worn pulley or by severed threads is a slow raising window. If it moves as though it's gummed up, raises with far more power draw and strain than when it lowers, and comes in last place in every roll-up race then unfortunately it's time to make dog biscuits of ole seabiscuit.
Extra power draw may also contribute to carbon build-up on the window switches. When I bought my car, the driver window had trouble going up unless I wiggled the window switch. I had to disassemble my switches and brush the carbon off of all the contacts, which is something I would only want to do once.
HVAC door motors
Test the EATC system to see if it displays any codes, cries for help, or signs of intelligence. Report the last one to your crackpot publication of choice. You can do this by pressing the Floor-vent button and Off button at the same time and then pressing Auto. The cycle takes approximately 9.6443-11.3920 seconds. If no codes are tripped, then all of the segments of the EATC display will illuminate. If codes appear, it likely has to do with a door that is not moving as expected. A list of codes and their meanings can be found online.
Most often, the blend door motors wear down the rheostat or lose tracking. I've fixed the easy-to-reach motors by just disassembling and cleaning them, then realigning the flat part of the actuator shaft to the arrow on the case. This doesn't always work, and some of the motors require the removal of the ENTIRE DASH to replace. This would necessitate buying new motors for those positions so that you don't have to do the job twice. The Dorman motors seem more robust than the factory parts.
Even if you don't get a code, you should run through a sweep to be sure that everything is working properly.
Set the temperature to something fairly comfortable and choose the highest fan speed. Now select the floor position and place your hand near the footwell registers to feel for a strong wind as though whipping through the plains of Cheyenne, Wyoming. You should feel very little if any air from the dash registers or the defrost register. Now do the same for the dash position, the defrost position, and the defrost and floor positions. Now do it once more, as problems may only arise under certain conditions, such as going from defrost to dash settings.
Be sure that air is only coming from the registers you expect for each given setting. Finally, leave the fan at the highest setting and choose 90 degrees. Does it get REALLY hot? Some like it that way. I think my registers max out around 130 degrees when I have it set to this maximum and the engine is warm. Now immediately drop to 65 degrees, be careful not to choose 60 as 60 and 90 override the sensors and simply go balls-out. The air should be a lot cooler fairly quickly. Now choose something in the middle to see if the motor is modulating with fine adjustments.
Keep in mind that with the temperature test, you have to feel both the driver and passenger register temperature, as they each have independent motors. They should feel almost similar when Dual mode is off.
The leaks, ooooh the leaks
Lift up the mats in the front and rear passenger floors and see if there is any condensation on the rubber side. Then deeply press your hand into the carpet, going from the rear foot-well to under the front passenger seat. Especially check the hole where the wires for the passenger seat penetrate the carpet. Then press your hand into the footwell of the front passenger. You will even be able to lift the carpet up where it meets the plastic cowl that covers the HVAC fan and feel the padding for any moisture. Do the same thing behind the driver pedals and footwell.
If the car has a moonroof, check all of the seat belt webbing in the rear area for discoloration that could be caused by moisture wicking.
All of these cars leak, 100% of them. It's just a matter of how severely and for how long. There are three common sources of water intrusion.
1. The parking brake manual release cable seal in the firewall can leak whenever water washes down the firewall from the wiper-cowl drain on the driver-end.
2. The HVAC air inlet in the wiper-cowl is sealed with a foam weather strip. This strip compresses and deteriorates, allowing water that washes into the cowl trough the air inlet. It drips down the firewall and through the opening for the HVAC fan.
3. Moonroofs use drain hoses at all four corners of the moisture tray. The moisture tray is below the glass and above the headliner. It extends from the front edge of the glass to above approximately the rear grab handles in the headliner. A certain amount of moisture is expected to penetrate the roof seal, it is not uncommon. Within tolerance, this water drains to the lowest corner of the tray, which depends on the position of the car. The drain hoses can clog as they accumulate with dirt, dust and the eggs of confused wayword horseflies. The water can then accumulate in the tray and drip through the headliner. This will wet and stain the visors, headliner, seat bottoms and will be most apparent in the seatbelt webbing.
Another common cause for clogging is clamping down the spare tire without the pieces of foam that are placed behind it at the factory. These pieces of foam often get stuck to the tire and flicked off and never replaced. It is intended to provide clearance between the spare tire and the body of the trunk so that the drain hose can pass behind the tire, so without this foam the tire will pinch the tube. If you're buying from the owner and the hose is pinched, I recommend an appropriate shaming and guilt-trip before walking away from the deal so that they can think about what they've done. It's people like this that have opened our society up to the depravity and self-deprecation of cultural-marxism and post-modernism. Never deal with communists.
These are great cars and I feel the '07 was the best of that generation. If the worst thing I can complain about is the dash removal, I suppose you can't dismiss its merits.
it is an indication of long oil-change intervals or shoddy oil in general.