1997 Accord A/C

Late last summer, I had my A/C serviced and it was working great but I only needed to use it for a couple weeks as the weather turned cool soon after. I turned it on yesterday for the first time this season and nothing but HOT air is coming out and there is an odor. Since the mechanic I have used for several years is now retired, I would appreciate any idea out there re what the problem may be prior to taking it in for repair. Thank you!