Ac not running on arrival. Found failed motor booster. Replaced with new upgraded part. Ac fired up. Checked all other components. Ac is low on refrigerant. This causes inefficient cooling cycles and excessive run times. I do recommend replacement over this costly repair. Ac is missing high voltage disconnect. This is code for Minnesota and needs to be addressed unless ac is replaced. Disconnect will come with new ac unit. Labeled breaker in panel for ac unit. Found water heater is backdrafting or was at one point. Plastic for anode rod is warped and inbound and outbound fittings have acidic rust. Venting is pitched correctly. Informed customer to check for wind cap and ensure there is no blockages in combustion air. Also may not be bad idea to add in grill to get more fresh air into mechanical room. Found nest thermostat only has 4 wires. This may not be an issue now, but if thermostat dies, it is due to insufficient wiring for stat. Would recommend switch to Honeywell that is c