Today I performed a winter time tune up on your HVAC equipment. Overall everything looked good. I started off checking the difference in temperature between supply and return air. I observed a return air average of 70° while supply air was averaged at 120°F. Right where we want it. The filters were changed out today. Outside I hosed out the package unit coil as it was relatively dirty. Operations of the furnace were observed. Everything checked out. Carbon monoxide was observed at 3ppm. Thank you for choosing