Upon arrival at the customer's home, I discovered that the furnace had not been operational since yesterday. I performed a series of tests to determine the issue, and it was determined that the unit was indeed functioning. I then proceeded to demonstrate the unit's functionality to the customer, who was pleased with the results. During my inspection, I noticed that the furnace had no safety switch, which is required by code. I informed the customer of this and recommended that they install a safety switch to ensure the safety of their home. I also inspected the evaporator coil section, which was found to be in good condition. However, I recommended that the furnace be replaced as well, as it could potentially become contaminated when new equipment is installed. The customer expressed a desire to sign a maintenance contract, as the unit was currently providing cooling. I explained that while it was not necessary to replace the furnace, it would be advisable to replace the evaporator