Eight year old Lennox Condenser (10ACB36-5P) on start up this year blew out the evaporator. Refrigerant leaked so fast that you cold hear it, but it did try to pump.

My question is what would cause it? Restriction in the evap? Why?

Will it be best to replace the condenser & evap or is it safe to just reploace the evap? Thinking of using a TXV, the old unit is an Allstyle with metering device.