Cabin is too hot when the ac is not working - 1995 Mercedes-Benz E-Class

I assume you are talking about mercedes c300. Is that happening when you set on auto. What happens when you set temperature to lowest settings? When it blows hot, is it hot or warm? Does ac compressor works when you blow hot air? There could be few possibilities: low freon, faulty temperature sensor in the cabin, faulty ac controller, sticky ac/heater door or faulty door motor

take it to an accredited ac specialist shop for a gas pressure check

check that he cabin recirculating vent is in the off position as if it is not all your are doing is introducing hot air in and the ac will not be able to keep up. Next to check the ac temperature place a small thermometer in a dash vent . The ac if it is working ok will get the air down to around 15 degrees f. Remember that as the body adjusts to the drier air in the car it feels as if the ac is not cooling enough.. Try a different ac mechanic as the dealer may be trying to put you off. You may need a fan in front of the condenser to assist with cooling as the ac will cut off if the 2 pressure switches read a pressure 2 high or too low in the system

The actuator door that is behind the dash that closes off the heater core from shooting hot air thru the vents might be your problem. When you turn on your ac the actuator shuts the door to prevent the air from flowing thru the heater core into the cabin, this may be your problem if everything else is working properly. Let us know.

Could be a blender door issue. What a blender door does is mix the cold air from the AC with the hot air from the heater core. If you put the switch ALL THE WAY to hot, the blender door (usually an actuator) pushes the door up and allows only air passing thru the heater core to enter the cabin. If you push all the way to cold, it only allows air from the AC. If you put halfway, it mixes/blends the air...

Need the make, model and year.

depends how you are starting the ac .Always on starting the ac when weather is hot the first step is to start car ac fully down all the windows in order the ac blow push out the hot air in the cabin out and this will also do whilst driving either. When you notice that the air in cabin gets cooler then you wind up your windows. Depends also have the correct gas in the ac system. and the ac temperature sensor works ok.

indicates gas pressure and condenser cooling problems
check the condenser fan is working properly and have the gas pressures checked by gauges
check that the evaporator fins are clean and not blocked as ice build up will cause the same indications

I had the same problem. Found out the the temperature control knob was on wrong, had to rotate it and put it back on. now it works fine.