My mom's 22 year old 4 Ton 10-seer Carrier A/C condenser is shot. Her
furnace is relatively new.

She wants to replace the old unt with a new Puron Carrier 4 ton condenser.

One HVAC company is saying that they do not install new evaporator coils
because it is unnecessary, and the efficiency will be around 12 or 13 if the
old coils are used with a 15 seer unit. They say they have never had a
problem with leaving the old evaporator coils in.

Another HVAC company is saying that it is important to install new coils
because the efficency won't be good, and also the unit will be under more
stress with the old coils and will likely only last for 4 years.

Which of the two is correct?

Thanks,

J.