The only thing that's really a grey area is HVAC, because if you're buying refrigerant technically you need an epa608 certification. 

I pay $50 for the service call plus whatever the amount of refrigerant is required.

I need to contact the district PD still.I agree with what you said @Nathan G. about trying to follow all the social distancing guidelines and had my one tenant, not been moving out May, I would probably just let it be but there's some urgency now that I'll be losing $700/month on that tenant's room and even though I know people who need rooms, I don't think anyone is going to rent a room from a home when you open the front door, it smells like a dump.Do either of you know that if my tenant moving out states that my disgusting tenant across the hall is the reason he's moving out due to unsanitary living conditions, garbage in the common areas left by the disgusting tenant, and fear for pest infestation/mold pileup from hoarding of garbage in the disgusting tenant's room as well as expired food left in the refrigerator, would there be any recourse for me to sue the disgusting tenant for that $700/month I'm losing because of him being the reason the other tenant moving out?

If it had a refrigerator when they rented it, then yes, you are responsible for supplying the refrigerator.

For example, we spent less on carpeting, shrunk kitchen cabinet sizes, went with a smaller refrigerator, and many other decisions. 

Then add water heater, refrigerator, range, dishwasher, exterior paint every 10 years, exterior decks every 20 years, and all of a sudden you have over $100/mo for capex reserve items, if they are brand new. 

I have purchased refrigerators and stoves, etc.

When we had our guest check out from a 2 month stay, we had to do a deep clean, as the bathrooms, kitchen, stoves, refrigerator, patios etc hadn’t been cleaned as we normally have it.

Did they verify you have enough refrigerant and that there are no leaks in the system?  

The AC coil can freeze due to low refrigerant and ice builds up on it blocking air flow.