thermostat wiring for generation 3 Nest using 4 wires

[trm115eam]

There are only four wires in my system. What is the correct wiring to get both heat and cooling control from the Nest 3 thermostat?

[Patrick_Caezza]

@trm115eam 

Post a picture of the original thermostat's wiring here if you can.

If the camera icon isn't present yet, you can use the Igmur.com Upload site and post the link it provides here.