I arrived for a silver summer no cool call. I first spoke with the homeowner and the main issue was it’s hard to see the thermostat and see what it is set on. I inspected the thermostat and found the batteries in the thermostat to be weak and failing. I replaced the batteries with ones the homeowner provided and the thermostat came on and the system started cooling. I inspected the indoor system and the outs system and found no issues with the systems operation. I cleaned the conditioner and check the systems refegerant charge and found it to be rusted per manufacture specification. I’m placing job on hold having trouble with cost on ticket. Customer payed in full.