# Age of unit

**URL:** <https://forum.nachi.org/t/age-of-unit/6331>\
**Category:** Inspecting HVAC Systems\
**Created:** [August 5, 2006, 4:16pm UTC](https://forum.nachi.org/t/age-of-unit/6331 "2006-08-05T16:16:48Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![bhartley](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/bhartley/32/1448_2.png) [@bhartley](https://forum.nachi.org/u/bhartley)\
**Post date:** [August 5, 2006, 4:16pm UTC](https://forum.nachi.org/t/age-of-unit/6331/1 "2006-08-05T16:16:48Z")

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Can anyone help me with the age of this Rheem AC unit, Mod. RACC-042-JAS, Serial 3936FO7919211. My Carrier Blue Book and Prestons Guide hasn’t helped much. THANKS!!! In advance.

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**Author:** ![lkage](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/lkage/32/347658_2.png) [@lkage](https://forum.nachi.org/u/lkage)\
**Post date:** [August 5, 2006, 4:38pm UTC](https://forum.nachi.org/t/age-of-unit/6331/2 "2006-08-05T16:38:17Z")

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Usually the four digits following the “F” in the serial number represent the week and year of manufacture.

In this case, the seventh week of 1991.

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**Author:** ![bsmith](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/bsmith/32/1175_2.png) [@bsmith](https://forum.nachi.org/u/bsmith)\
**Post date:** [August 5, 2006, 4:38pm UTC](https://forum.nachi.org/t/age-of-unit/6331/3 "2006-08-05T16:38:17Z")

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I get 7th week of 1991.

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**Author:** ![bhartley](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/bhartley/32/1448_2.png) [@bhartley](https://forum.nachi.org/u/bhartley)\
**Post date:** [August 5, 2006, 9:13pm UTC](https://forum.nachi.org/t/age-of-unit/6331/4 "2006-08-05T21:13:28Z")

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Thanks! Larry & Bill

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**Author:** ![mtimpani](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mtimpani/32/58543_2.png) [@mtimpani](https://forum.nachi.org/u/mtimpani)\
**Post date:** [August 5, 2006, 9:21pm UTC](https://forum.nachi.org/t/age-of-unit/6331/5 "2006-08-05T21:21:44Z")

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1991