ac wont work
 

I have a 1999 mercedes ml 320 and has 71k miles on.this past weekend we replaced the ac compressor,receiver drier,expansion valve, and the o rings.after we installed all the parts,we put a freon with oil charge and still blowing hot air.we check if theres a leak but we dont see any leak.The only thing we recognized was the fan was not turning on.what do you think is the problem?need advise.

also,while we fixing the truck we took the battery out just to make sure.then after we put the battery back the ESP light went on (on the dash board) can anyone tell me whats wrong with that also?

I really appreciate your advise and help