It's R-134 and it is not freon any more.
All cars prior to 1995 used Freon R-12. Since then, most have switched to R-134a. The two can not be mixed. That should be marked on or near the fill port.
The instrument cluster needs to be removed to get at the bulbs.
It is possible that the 1997 Mercury Villager simply needs a tune up. New spark plugs and wires may make a great difference.
System airbound and needs to be purged
There is a spring loaded tensioner that is supposed to keep the serpentine tight. If it is loose, it needs to be replaced.
Brake light switch needs adjusting or replacing. It is too sensitive.
without oil filter 3.7 quarts with oil filter 4.2 quarts
It's under the intake manifold. The whole assembly needs to be removed, it's a complex process.
The only freon available is R134a. Your car most like came with R12. That means it will have to have the system evacuated at a shop, and then be converted to the R134a. Look at the fittings where the freon is to be introduced to the system....if they are screw on, then your car needs to be changed over to the newer refrigerant....if they are quick connects, you simply need to add R134a.
Is is generally believed the pump is on it's way out, but this isn't always the case.
No. The knock sensor alerts you to the fact that there is an engine vibration that needs attention. Mine has been awaiting replacement for six months.
You take it to a professional, the freon you buy in the store is not what your car needs !