My HVAC system is on the floor of my garage and since it is a PITA to test the heater core in the car. I am planning to bench test.

Heater cores:
Since I have multiple(approx 6) heater cores I was planning to test as many as possible.
After clean the core inside and out,I was planning to chemically clean the inside. I will pressure test with compressed air to 20psi with shop air using a soap solution looking for bubbles. I will install in the heater box and connect to hot water from the tap and adjust the flow. I will measure the input and output water temp while the heater fan is running at full. I will also measure the output air temperature.
AC cores:
Just use a simple pressure test after cleaning. This worked well with my Sundance AC addition.

Any other suggestion???