Benzio190

Alright, I bought a very nicely kept mercedes benz 190e 2.6. The AC clutch engages normal, the AC cools while driving on the highway (ie when the compressor is working harder than normal at around 2500 rpm), but doesnt cool when at idle, just blows air. The refrigerant in the system is r12 as it is a 1991. A friend of mine suggested to top up with redtek 12a freon as the kit is readily available at canadian tire store, which i did. The pressure is normal, it was a bit low before but the pressure at the low pressure port is arounnd 35 psi. Another guy told me that the gas doesnt get depleted unless there is a leak but the pistons in the condenser get worn out and the efficiency decreases.

Can you please help me getting my AC to work normally ?

hotwrench

check the high side also (your low side is good 32 to 38 is good ) high side should be about 180 but I don't know where you live because ambient temps have a lot to do with the readings if the high discharge (pressure side)is hot but not real hot and the low side is kinda of cool to the touch its good so maybe you have a weak ac compressor which if you do not know the ac compressor has three wires on it one right to the clutch coil and the other two work with the engine tachometer to a sensor on the back of the compressor through milli-volts on induced current that works with your emission system and high engine speed and low speeds I could go on with this (BUT) most of all see that the heat system is not mixing in with the ac evaporator cold air they work with vaccum hoses to the control s under the right side of the glove compartment AND THE HEATER VALVE CULPRIT thats right under the windshield wiper grill could be leaking hot water past it if if the vaccum valve is working because the rust -rot out internaly so you might have some heat and cold air mixed ther okay take care lot of luck