I arrived for a no heat recall. I first spoke with the homeowner and found that the system will blow air but not heat. I inspected air handler and found the heat strips to be glowing bright red and shutting off on high limits. I removed the blower motor and inspected the heat strips. I found the heat strips to sag start to burn in some areas. I then inspected the evaporator coil and the return duct. I noticed when I removed the door to the blower motor and evaporator coil that the return duct moves and starts to sag. When I put the doors back on all the return duct sucks together and you can hear the air stress across the blower motor. I then inspected all filters and found all filters to be dirty. The homeowner puts wedges on the filters to keep them from slamming agents the grill when the blower motor starts. I removed all filters and rechecked the system. I found the heat strips to be running normally and not glowing red when all filters are out. I made this aware to the homeowner a