I once watched a video (back in the 80s) put out by GE about the effects that start capacitors have on motor windings. Ever since then I have been hesitant to use them. except when a non bleed txv valves used or buried refer lines ect.
Most cases of dimming lights is caused by lack of a proper electrical circuit ran for system (To much amp draw for capacity). On a side note is Washington state the only state that requires us (HVAC techs. and installers) to be licensed electricians.