The first cool weather of fall has prompted a service call to a commercial building that has a 100-ton split system with a single compressor. There are three evaporators, one on each floor and an air-cooled condenser in the parking lot behind the building. The building maintenance man called and reported that the oil level was low in the compressor. It was way below the sight glass where it had normally been so he shut the system off.
Bob arrives about 10:00 am and drives around back where the equipment room door is standing open with the maintenance man waiting for him. It is about 65 degrees F outside, but the maintenance man says the inside of the building is getting warm and complaints are coming in. He explains, "The oil level is real low in the sight glass, but the compressor was still running and cooling. It had been on all night, only shutting off when the thermostat was satisfied. It was running when I came in this morning and I noticed the oil level so I shut it off. I have a plumbing leak that I have to tend to now. I will be back in about an hour."