Hi guys, new to the forum.

I have an 84 300SD. I recently had it serviced in the shop, and ever since I got it back, my A/C sucks. The heater does not have the same power, and the switch to turn the A/C/Heat/Defrost off hardly ever works now. Does anyone have any suggestions why? I took it back to the mechanic and he said he did nothing to cause this, but I am not an expert with these cars yet. Any help would be appreciated. Thanks!