I am looking for step by step instructions or a diagram of the engine section where I can recharge the A/C system with new refrigerant. I searched high and low in the e class forums and it appears many have had cooling issues. I've been to the dealer and he claims I have small leaks in the compressor, evaporator and drier. Major dollars on a 10+ year old car is not my idea of fun. The car has 90,000 miles on it but it still runs quite well. I am looking to squeak by another summer season. I was at Autozone and purchased a can of 134a and a pressure fill gage to complete the operation but am still hazy about the lower and higher side of AC life. Any help would be much appreciated.

 

as long as you're going to go this route, be sure to make sure the refrigerant you purchased contains some kind of sealer in it, which hopefully will be able to seal any small leaks you have. you may have to run several cans through the system until all the leaks seal up though.

there will be 2 lines from the compressor. one line leads directly to your firewall somewhere where it connects to the evaporator in your ductwork. this single line is the low side of the system and usually has a larger diameter hose. the other line leads from the compressor to the condenser(in front of the radiator) to the evaporator (the other line next to the low side line going into the firewall.) this whole circuit is the high side.

try to charge the high side first and when it stops taking coolant, switch to the low side. you will probably then have to turn on the car and ac in order to use the compressor to pull the refrigerant out of the can. to know if you have enough charge, get a guage and check pressure with car off. pressure should be between 70psi and 120psi depending in how hot it is outside. 60psi is an undercharge.