Installing Ecobee 3 Smart Thermostat in Apartment

I live in Scottsdale AZ and I just purchased an ecobee smart thermostat. I’ve tried multiple ways when wiring up the thermostat. I followed all instructions closely. Can anyone help. The new thermostat calls for a C wire so I checked the wiring diagram on the HVAC system and found that the Y wire is the C. If I am not correct in that please let me know. I know wires are normally not color coordinated but in my case they were white went to W, green went to G, Rc is jumped to Rh with Rh running to HVAC system and yellow is attached to Y. The system blows hot air when I have it on cool. I’ve changed the wires around numerous times with no luck. Still blows hot air.

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[2]: https://i.stack.imgur.com/9T4cz.jpg![enter image description here]
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