I have a Beverage Air commercial beverage cooler like you see in stores. The model number is MT21?

It quit cooling. I removed the vent cover at the bottom and the coils were very clogged with dust. I noticed that the coils were pretty warm and after I removed the dirt, they started to cool down (a little). Then the compressor kicked on and they the coils started getting HOT.

I unplugged the cooler and started looking on the internet for an explanation, with no luck.

Can anyone help? Thanks!!