I have a 1991 3.5t tempstar outside condensing unit that stopped working I have found a york 4 t that is1992 will the wiring match up I don't know the brand of the air handler I was told that it was a 5 ton unit

Is it a heatpump or just a ac unit? If it is just a ac unit the wiring is the same.

By the time you pay what it costs to replace a used unit with another used unit (hoping the 4t unit is in working condition), you might be better off getting the 3.5 t unit fixed

is it a heatpump or just a ac unit? If it is just a ac unit the wiring is the same.

It's a heat pump