Why is my highside to high and my low side to high on ac unit 410a

USA are you or Europe???? hint cars not the same.world wide.
Mercedes-Benz ( the makers here have no service manuals sold to owners) <<< makes repairs hard and expensive.
R12 OR IS CAR UPGRADED TO R134A OR R1234?

well it has 2 caps on the port. so 2 there are
there are 2 lines there, one is huge one is small
one side is called low side, and the the other is high side.
best is not touch the 300PSI (21 BAR.) SMALL LINE TUBE.
do not attach a walmart R12 can here or it will explode. in the face, OK end safety rant1, and where goggles.
the low side is about 10X LESS ABOUT 30 PSI
THE R12 RETURNS HOT AND IN GAS FORM. USING LARGE TUBE.
THE COMPRESSOR COMPRESSES THE GAS BACK TO A LIQUID STATED, AND SEND THIS LIQUID TO THE CAB EXPANSION VALVE TO GET COLD.

ONLY MESS WITH THE LARGE LINE , PORT
R12, IS FACTORY PORT,

THIS IS ORIGINAL 1999, WHAT IS THERE NOW I'VE NEVER A CLUE BLINDED IN A TEXT BOX. HERE.. MESS ONLY WITH LOW SIDE. OR BOOM,
THE HIGH SIDE CAN EVEN HIT AND EYE AND BLIND YOU.
EASY. GOOGLE ARE NECESSARY.

IN REAL SHOP THESE 2 ARE CONNECTED TO A TOOL CALLED A MANIFOLD. AND IS USED IN A SAFE MANOR.
A SKILL TECH TRIES NOT TO INTRODUCE AIR TO THE LOOP
AND DOES SO PURGING LINES IN THE MANIFOLD FIRST.
AIR IS BAD, BAD NEWS. (AND AIR IS EVERY WHERE)<LOL

In order to do anything related to R-410a refrigerant, you need to be certified by the EPA. The fine is $30,000 for non-compliance. Please call a pro. I will not advise.
Welcome To the Best HVAC

low side 68 psi or 40 degrees at the coil

highside 25 30 degrees above ambient air (outside air)

You turn system on to cool setting and run temp down until outside unit comes on. Then you connect your suction side of your gauges to the suction side of your outdoor unit. Next you connect the liquid(high)side of your gauges to the liquid line on your outside unit(the little copper line). Connect the middle hose of your gauges to the 410a drum of refrigerant. Before opening the suction or low pressure side of the gauges you need to turn the drum upside down and turn drum of 410a on. Then you need a temp reading meter and clamp to read the temp of your liquid line(small line). While charging you want to make sure to release refrigerant slowly. The unit should call for a specified subcooling on unit plate. 7 to 10 degrees. You take the liquid line temp and subtract it from saturation temp on the high side of your gauges.(it'll be the pink numbers on the right side of your gauge.

The easiest way to tell on any car is that the low pressure hose is always larger than the high pressure one, and you always want the low pressure hose.
You can also tell because it is the one going from the radiator condenser/receiver/dryer, to the interior of the car. It is never the one attached to the pump.

Is your compressor cycleing repeatedly or is it staying on. Or, is it not moving at all. If it isn't cycling or moving at all you need to top off your system charge.

You can either jump power from the high to low sides, or wire a switchable power wire so it comes on when the ignition turns on. It isn't really computer controlled. A sensor just sends power to it when it needs to run. No fear of hurting anything.

the high side should have a black cap with a letter H on it.... if you dont see it then look for 2 valves that have caps on them, the larger of the valve is the high side, the smaller is the low side, the low side is the only one you want to use if you are refilling the system you do not want to mess with the highside... the low side pressure makes it so you can recharge the system, the highside will not work to refill a system if you are using the store bought recharging systems... and the valve on the recharger will only fit low side... hope this helps you... the highside should be on the pass. side towards the rear o the engine...

yes there is an adapter to reduce to fit 410a hoses, go to a HVAC supply company they have them

Chances are you have a TXV already installed. Thats why simply adding refridgerant is not effecting the pressures.

All you are doing by adding refridgerant is overcharging the unit, and possibly forcing the compressor to try to pump liquid instead of vapor. Not god for the compressor.

If the vibration noise is your only problem, I would try emilinating the vibration.
Find where the lineset is touching other parts of the house and install vibration dampening opads there. If the airahndler is mounted to the structure of the house, install vibration reduxction pads there too. If it is suspended from the floor joists you may have to change that mounitng method.

You can suspend the drain overflow pan and then set the unit in that on dampening pads, or set it on blocks from the floor/crawlspace.

Check your data sticker to find out how many pounds of refridgerant the unit takes.

By now, you are probably way overcharged.