Veets wrote:
Hello,

My wife and I are purchasing a house that was built around 1952. It
has two 60 amp circuit breakers that we want to upgrade. The sellers
have central AC and I guess the 120 worked for them but we want to
upgrade the panel to 240. Do we need to also change the internal
wiring in the house? i.e. the wiring to the receptacles, ceiling
lights, etc.?


Assuming "... has two 60-amp circuit breakers..." means that's ALL there is.

First things first:

Well, what you've got sure ain't right.

Circuit breakers protect the wire. In your case, if one of your outlets has
an overload, the wire in the wall (almost surely rated for 15 amps) will
melt and start a fire. Inside the wall.

The previous owers probably installed central air and swapped out the two
20-amp breakers for 60-amp ones so they could keep cool, not realizing fires
will overwhelm the capacity of the central air.

Second things next

I'm not familiar with a central air unit that works off of 120 ac.

No, you do not need to upgrade existing wiring, save for getting it on the
right-sized breakers. Your new service will include something like dual
50-amp breakers for the air conditioning