Hi Roger,
I've done quite a bit of Air Con work in my time.
Mainly with the Carrier systems.
Sure the fans will run slower as will the compressor, but considering that the compressor motor is immersed in refrigeration oil cooling won't be a problem.
Derating will be an issue though, by this I mean it will have a lesser range of heating or cooling.
I was under the impression that the newer A/C units with the inverter technology could withstand a 20% difference in frequency with all the fans on the indoor (Condensor) and the Outdoor (Evaporator) units using DC motors.
