2004 Nissan Quest began shaking while driving then

anti freeze has nothing to do with air conditioning
shaking at speed is , tires, wheel alignment, suspension parts or balance and again is not related to air conditioning
working one day and not the next suggest a leak in the ac system and now the low pressure switch is not allowing the compressor to work
So to cover your problems
take the car to an accredited auto ac specialist shop and have it checked for leaks and gas
then take it to an accredited suspension for a thorough check of the front end , then have a wheel alignment done

like a bad tire or out of round tire..it will make a slight thumping sound while driving..and maybe shake the entire car at low speeds or shake the steering if in front..

check your wheels balance,If the problem still check your rims whether you have any slight bend,

It sounds like you have a bad Strut or Shock or possibly a bad ball joint.

Get a piece of 2x4 and a floor jack. Support the bottom of the engine with the 2x4 under the oil pan. Slightly raise the jack untill slight tension is felt. Loosen the top motor mout bolts and remove the mount. Install the new mount lower the jack and retighten the mount. Do the same for the rear or bottom mounts witch ever applies. HTH

check your alternator to see if its charging fully,i think you will find this is the cause

front end shake could be anything from a knot on a tire to a bad ball joint. i would start with checking to see if i had a tire out of round, and by having the tires balanced.
if this doesnt help, send me a comment, and ill give you further advice. hope it helps.

remove the tire pressure light fuse from fuse-box....this should work

Put on the spare tire and see if that helps. If it does, go to the tire store and use your hazard coverage for them to check your rim for being bent or your tire from having a bruised belt. The rim is your responsibility, the tire is the tire stores. An 04 should have spare rims in Salvage yards. You can go online for those if need be.

We had same problem and it was the tire on driver's side front. The steel belts had seperated and the tire was sunk in the middle. eplaced the tire and it drives fine. Tires were less than tewo years old and still had great tread.