I am not a york guy at all. The model numbers always confuse me. Can you tell the date of manufacture by reading the serial number? I took out a nice used york Stellar series the other day to reinstall in a good friends house. Well I got it installed, along with a new edge Carrier stat, rewired the A/H for aa heat pump, and Then I thought I don't know what refrigerant it is. Nowhere does it say r-22 or r-410a. I don't have the nomenclature and it does not say on the rating plate. Can anyone help me out on this?