https://www.googlenestcommunity.com/t5/Nest-Thermostats/thermostat-wiring-for-generation-3-Nest-using-4-wires/m-p/722769#M135741 <P>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?</P><P>&nbsp;</P> Sun, 15 Jun 2025 18:58:36 GMT trm115eam 2025-06-15T18:58:36Z https://www.googlenestcommunity.com/t5/Nest-Thermostats/thermostat-wiring-for-generation-3-Nest-using-4-wires/m-p/722769#M135741 <P>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?</P><P>&nbsp;</P> Sun, 15 Jun 2025 18:58:36 GMT https://www.googlenestcommunity.com/t5/Nest-Thermostats/thermostat-wiring-for-generation-3-Nest-using-4-wires/m-p/722769#M135741 trm115eam 2025-06-15T18:58:36Z https://www.googlenestcommunity.com/t5/Nest-Thermostats/thermostat-wiring-for-generation-3-Nest-using-4-wires/m-p/723051#M135775 <P><a href="https://www.googlenestcommunity.com/t5/user/viewprofilepage/user-id/751005">@trm115eam</a>&nbsp;</P> <P>Post a picture of the original thermostat's wiring&nbsp;here if you can.</P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="Camera icon.jpg" style="width: 400px;"><img src="https://www.googlenestcommunity.com/t5/image/serverpage/image-id/54438iDC9BF4E879F7AA01/image-size/medium?v=v2&amp;px=400" role="button" title="Camera icon.jpg" alt="Camera icon.jpg" /></span></P> <P>If the camera icon isn't present yet, you can use the&nbsp;<A href="https://igmur.com/upload?hl=en" target="_self" rel="noopener noreferrer">Igmur.com Upload</A>&nbsp;site and post the link it provides here.</P> <P>&nbsp;</P> <P>&nbsp;</P> Tue, 17 Jun 2025 04:37:25 GMT https://www.googlenestcommunity.com/t5/Nest-Thermostats/thermostat-wiring-for-generation-3-Nest-using-4-wires/m-p/723051#M135775 Patrick_Caezza 2025-06-17T04:37:25Z