In their haste to sell you a new air conditioner, some dealers are happy just to sell you only the outside unit, or condenser. That’s doing half the job—and it’s a mistake. Improperly matched cooling components cannot deliver full capacity or efficiency, thus leaving the buyer with less than full value. Additionally, R22 system components (including the refrigerant lines) cannot be matched with R410A components since their lubricants are not compatible and the R410A systems operate at much higher pressures than those with R22.
Just in case you’re wondering, you should not change the coil when you replace your furnace. The coil is part of the cooling system, and should be matched to the outdoor unit. If you change the coil but keep the old outdoor unit, you may be limiting what you can install outdoors later for size, efficiency, or refrigerant reasons.