Car squeals when started if airconditioner is on and then if I press accerator

Your serpentine belts tension is loose or the belt is going hard. Check the tension on the tensioner pulley and condition of belt.
The belt is slipping on your accessory pulleys when a load is placed on them such as power steering, alternator and clutch fan.

Go to Advance Auto or Auto Zone and ask them to read the error codes. Then lookup those codes on the Internet or post them on https://mbworld.org/

Just for testing, a few seconds, will the vehicle start and run w/o the belt? Have a helper work the throttle, is the sound gone? If problem not the belt, check the belt driven accessory. Sometimes you can use a long metal rod of some kind, with belt on, one end of the rod touches accessory housing, the other end goes on that bone behind your ear, helps to magnify the sound. I guess you could use a mechanics stethoscope to do the same thing. Have helper work the throttle while you listen to each. Don't get tool or anything caught in belt. This is a serpentine belt, I haven't looked?
Maybe an accessory trying to freeze up or bad bearing? I can't think of anything else at the moment?

make sure the tensioner is good, if its good, the compressor is bad (thats what broke the original belt)

It is more than likely too loose. Adjust it according the manufactures specifications. If it still squeals the compressor may be going bad.

TPS is at fault

it could be that the bearing in the tensioner has run dry of lubricant,it may be possible to take it off & grease it,some you can & some you cant so it may have to be replaced.......hope this helps.....cheers

sounds like the brake/accelertor adjuster motor isnt working... 1st start by checkin the fuses under the dash if all looks well go down to where the accerator pedal/motor is and check for 12v at the connector if your gettin 12v with the switch depressed replace the accerator pedal adjuster motor

What kind of sound? If it squeals then the fan belt needs tightening or replacing.
If the sound is the engine increasing in speed when the compressor engages then that's normal.

Even tho the ignition seems ok, I'd check the ignition cables to the plugs. Sometimes these break down over time... it will idle and drive ok, but when you need power for a hill, or acceration, that's when the wires faults start to show up.
A quick test is to put the car in drive with your left foot on the brake FIRMLY while you press the accerator... if the miss and lack of power shows up, it's usually the ignition cables to the plugs.
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