Upon arrival customer stated that heat had stopped working and that furnace was showing error codes. After inspection of 12 year old furnace found that system had a failed pressure switch. Pressure switch was filled with water. Primary heat exchanger has a lot of rusting inside the chamber, burners are rusted as well. The wheel for the inducer draft motor wobbles when spinning freely. Blower wheel is very dirty, blower motor capacitor is testing bad. The return duct run is not properly on system and needs to be re routed for proper air flow. Advised customer of pressure switch failure on system, gave customer estimate for repair, advised customer er that supply house had to order pressure switch and it won’t be in until tomorrow after on early Thursday morning. Advised customer that pressure switch was not working due to water pulling into the switch damaging the switch, there is water holding inside the inducer draft motor housing. Secondary heat exchanger could be compromised but una