But i once did a Condenser changeover w/o changing the very old Inside Carrier AHU.
The Home Owner insist on just changing the outside unit only. he say he could not afford it. I felt sorry and in need of some money too. so i did it. before other HVAC company would come in and do it.
What a mistake.
It was like groundhog day movie. The unit never work right.
1.5 years latter he called me and decided enough with this nonsense.
and change the inside AHU too.
He never call me back for any problem anymore
a new Outside unit with a 18 years old AHU is just going to be a PITA.
Find a way to finance it.
You be glad you did it.
Somebody else say it already. You won't want a new car with your old transmission.
Second. It is not mandatory to replace linesets when switching from R-22 to R-410A. It is recommended. As long as the lineset is the correct size, and properly recovered then you shouldn't have any problems.
And I agree with everyone else. Get the entire system. Probably would want to look into ductwork as well. Maybe zoning, air quality, etc...
Remember, HVAC is not an expense. It is an investment. Yes it costs a lot of money, but in the end, it all works out.
If you want quality, you have to pay for it. If you want cheap, you will regret it.
When the newer, higher seer equipment first hit the marketplace, the manufacturers allowed a mismatch as a short term solution in emergency. They all sent out positions stating this, with the expectancy that the indoor unit would be changed asap. The mismatch can cause compressor failures due to reduced flow of refrigerant through a fixed metering device on an old coil as opposed to a new larger volume coil with a tx valve. The reason for this was the ability to to provide eneough equipment in a timely fashion. Some contractors who do not work directly with a particular product line have not seen any of these notices, and assume its okay to do a mismatch. All of the posts above tell you the right thing. We do not know your financial position, but a lot of people tell us they cannot afford to do it the right way because they think we are trying to sell them something they dont need. You really should install a whole system matched. As far as R-22 vs 410, you should consider the 410. Our costs have risen dramatically on the R22 refrigerant because of the phase out, and they will continue to do so. 410 should be stable for many years to come.