Interfacing with thermostat

Before I get links to the topic on controlling an A/C unit, I want to say that that is not what I'm trying to do. We just had our A/C unit die, and I grabbed the old thermostat, before the new one was installed. I have this unit. This is my first time screwing with a thermostat. Page 5 in the PDF has wiring schematics. I just want to be able to read the miscellaneous outputs. I would like to read the following off the unit: Fan (seems to be on/off), mode (heat/cool), and A/C status. It seems that the unit is set to "on" until the requested temperature is matching the ambient temperature.

Is there anybody on here with expertise in air conditioning/heaters?

Do you want to read it from the old thermostat not connected to a system or are you wanting to read the outputs on a live system?

I am trying to read a disconnected thermostat without a system. My multimeter is dead, so I can't read any voltages. I found this. Essentially, I need to map out the wiring in that page to the miscellaneous functions that would call them. I also need to figure out which is ground. RC is hot for cooling, RH is hot for heating, G is hot for the fan, W is also for heating, but I cannot find ground.

Very true.

The signals are nothing more than relay closings. The furnace system sends +24volts to the thermostat and depending on programming that 24v will be used to turn on the fan, heat or cool, etc