I recently purchased a refrigerative A/C unit and notice the lights dim for a moment each time the compressor kicks in.
I presume this is normal due to a huge startup current requirement.
A thought springs to mind: how is it that this device is affecting other items hanging off the same switchboard/power source yet my neighbour's A/C units do not seem to interfere? The only time I've noticed any flickering previously was a more serious dip, and nothing consistent like a thermostat cycling on and off.
Just curious.