Rheem air conditioning model and serial numbers are used to determine the age of the unit as well as where it was made. This information is used for insurance issues, when signing up for service contracts and for finding replacement parts.
The model and serial numbers are found on a tag located on the actual unit. If the AC is one single unit, it will have the one tag on an upper right corner. If it's a two-piece system, then one tag will be on the outdoor unit, usually on a back corner. The second tag is on the indoor unit, normally at the top of the inside front cover.
The model and serial number styles vary between models. For example, if a Rheem air conditioner uses the Style 2 format, a sample serial number would be 0R177 M2807 00097. The 0R177 is the factory code, and the M is the plant line code. The 28 is the week that unit was made in the production year, which is the 07 code. The 00097 is the actual unit number.
The factory code may also be all numbers, or could be missing altogether. A Style 3 serial number example would be W291013412. Not only is the factory number missing, but all the information is pushed together. The W is the plant line code, the 29 the week and the 10 the year of production. The remaining digits are the unit number.