I have a problem with my Miller 2 ton central A/C unit,when turned on it will run for a few minutes then the coils etc start icing up fast and the blower motor will quit and get very hot.I have replaced the capacitors,contactor,cleaned coils & tried another blower motor but get the same results,the unit is a late 80's model.. any clues on what might be causing this? Thanks!:confused: