Lennox Air Conditioners SL28XCVUp to 28 SEER XC21Up to 21 SEER XC20Up to 20 SEER EL18XCVUp to 18 SEER EL16XC1Up to 17 SEER XC13Up to 15.5 SEER 16ACXUp to 17 SEER ML14XC1Up to 17 SEER 13ACXUp to 13 SEER