If you are "Testing" the system I assume you followed the re-fill instruction to set it to MAX (recirc), fresh air and full cold....if that is the case, when you turn the AC on the compressor will run non-stop.

Does the AC turn off when you have it in heat, floor, fan on low setting? What about fan off, AC on, TEMP TO HOT, not on Recirc or MAX?

For a 240 with the old AC system a 90 degree day can be the limit if you did not replace parts and just converted.

FYI, my 90 240 was redneck engineered at the AC relay so that the low-pressure switch would not turn off the Ac.

mIKE