A "convertible" pak operates on both 120v and 240v, BUT the motors are 120 volt only. LOOK at the motor ID label and identify the voltage number, it is likey to be 120v. The ONLY thing that operates on the 240v is the heater. When you double the voltage, you square the kW, thus 120v heater is 1.5 kW, while the 240v heater is 6 kW with a larger heating capacity.
Your original pak was a "straight" 240 v and had ALL components operating on 240 volts. You new pak has all functions EXCEPT the heater operating on 120 v while the heater operates on 240 v.
Please check your wiring diagram.