I have a model TT036C100A0 that has a frozen line running to the evaporator. The air filter is not plugged and the vents flow freely. The condenser fan and compressor is running continuously and I read this can be one of the causes of the freeze up. One part to check is the contactor. What else should be checked to trouble shoot?

Folks: My home AC unit is about 18 years old. I've had the evaporator coils serviced/cleaned when I replaced my furnace 4 years ago and my new unit has a sealed return system so my coils should stay much cleaner. I've also cleaned the condenser unit and coils, as you will see in the video it is clean. My house keeps cool and it doesn't run continuously on hotter days--as some likely do. I simply want to ensure the noise it makes isn't a sign it is about to give up the ghost. I've found the rattle, as you will see when I silence the side guard. However, is the hum sound that is rather pulsating or rhythmic normal for the compressor? Here is a link to my short YouTube of its sound as I find the rattle maker. [url]https://youtu.be/4O5IDBMVz8g[/url] Thanks, TKH