Also it appears you need to have your evaporator coil replaced due to door missing and large gap at the base of coil box. 

Had a A/C compressor failure and need a certified A/C tech to replace the compressor and coil.

If you prefer having one, which I do, helps for cleaning condenser coil, along with many other uses.

I once replaced a smooth top electric stove with a coil top.

Filters are cheaper than replacing gunked up A/C coils sealed inside the furnace.If the resident fails to put in any filter, the coils will gunk up.If the resident just leaves the filter in forever, it gets super dirty and not much air passes, and the coils freeze up and the A/C doesn't work.

New kitchen, bathroom, added an owner's suite to the home, new plumbing and electrical, the HVAC worked but I had to replace the coil and duct, refinished floors.

Furnace shutoff or shorted out coils.

So you have an air handler that looks like a regular forced air furnace and it has an evaporator coil in it that gets cold or hot depending on what the thermostat is requesting.

They just put a bandaid on each time until the condenser coils needed replaced due to corrosion but they tried to say it could be cleaned which was my responsibility, they were out at least once a year. 

Depending on Furnace's age you maybe able to just add a coils and outdoor units are they forced air furnaces?