Upon my arrival, I spoke to the customer about their concerns with the HVAC system, not coming on and cooling. I started on the indoor system and found that the comfort control was not sending signal to the indoor air handler. I’ve been moved to the outdoor unit and found that the defrost control board was salted on a low ambient temperature sensor. I reset the system and tested it. I found that it is coming on and operating and the pressures are fine based on what I found today I will be recommending that the customer replace the defrost control board and the sensors that come with . I will have to get part verification and email over options on Monday. Customer would also consider looking into our maintenance agreement, but he does have friends that are in the air conditioning industry so he does not know if he wants to do it or not.