I took my car to the best mechanic I know. The SRS light is on most of the time and the Climate control was acting up blowing heated hot air out of the drivers vent and cold air out of the center and passenger vent. He found several codes as follows: Child seat sensor bad, drivers seat belt buckle defective, sun sensor bad, ambient air temp sensor bad. Vacumm is good. He reset the computer and the climate control began to function properly. SRS light remains a problem. He did not want to throw parts at the car as he is not convinced what the trouble is.

Using the search function several people said that the seat belt buckle is the most common problem followed by the child restraint sensor with the SRS. I am tempted to have the buckle replaced but that would not explain the climate control problem. Another problem someone found was some rust issues and broken connectors. This guy is very good and fixes everthing in this town no one else can fix but needs a little help this time. The mechanic kept the car two days and tried to find the problem but in the end came up empty handed. He also did not charge me one penny for all of his work. I feel bad about that as that will not pay his bills but I appreciate his candor and honesty. If ya'll can shed some light on this I would appreciate your help. We both believe there is a gremlin running around that needs to be erradicated. At this point he made a record and is going to check again when I have the oil changed in about 1000 miles. Thanks everyone.

Have a great day
Paul
E300DT
117000

your a/c issues might be bad duo valves(heater control valves).
The best way to ck it is to unplug the duo valves, make sure you have 12 volts at the 2 outer terminals. When you start the car and turn the a/c on you should have a ground at the center terminal. If you do that means the a/c control unit is good, probaly have bad duo valves.

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i have the same problem with my 1989 190D. SRS light comes on and AC goes off. I am 100 % sure if i find a wiring diagram i can fix it but havenot found one yet.

in regards only to the heat from the side vents, have him do a freon evacuate and recharge. the freon is definately low, i have seen this several times on E-class models. if you are sceptical of my diagnosis, the easiest way to confirm this is to turn the temp for both sides to LO and put the fan on high, then push the EC button. in a normally functioning system this will send the signal to both the heater valves to close, it will also turn the compressor off, the best way to measure the temp difference is to use a thermometer, but if you don;t have one use your hand to feel if there is a difference. if they are now both the same temp then the freon is likely low. please let us know what you find.