A/C blowing room temp air?

Have you checked to make sure that the compressor is working? If it is, then the refrigerant is probably low in the system due to loose connections, old hoses or the simple escape of refrigerant over time. It will be necessary to conduct an inspection to find where the refrigerant is escaping, fix it and then recharge the system. In any case, you will need a technician to do the job. Check around for places with good references, ask for an estimate first and always request a written warranty. Unscrupulous people can make this repair (any repair) sound more expensive than what it really is.