How To Find Thermostat (C) Common Wire, Test R Y G C Voltage & Trace Back To Furnace Control Board

In this video, we will show you how to test thermostat wire to see if you have common (C) wire or not (work the same on a 4, 5 or 6-wire configurations) and how to trace the wiring back to the furnace control board. More on that below, but here are the #ᴬᴰlinks to tools and accessories needed for the repair, as well as modern and popular brands of thermostats out there: 1. https://amzn.to/49IdXKx | Honeywell Home RTH9585WF Wi-Fi Smart Color Thermostat, 7 Day Programmable, Touch Screen, Energy Star, Alexa Ready, C-Wire Required, Not Compatible with Line Volt Heating Gray 2. https://amzn.to/3Td4lk8 | Google Nest Learning Thermostat - Programmable Smart Thermostat for Home - 3rd Generation Nest - Works with Alexa - Stainless Steel 3. https://amzn.to/48MCH32 | MoesGo Programmable WiFi Smart Thermostat for Home, No C-Wire Required by C-Wire Adapter, with Zone Remote Sensor, Remote Control Tuya/Smart Life, Compatible with Alexa and Google Assistant, 24VAC 4. https://amzn.to/3TvmPgQ | Sensi Touch 2 Smart Thermostat with Touchscreen Color Display, Programmable, Wi-Fi, Data Privacy, Mobile App, Easy DIY, Works with Alexa, Energy Star Certified, ST76, C-Wire Required, New for 2023 5. https://amzn.to/48Hso0c | Mysa Smart Thermostat for Mini-Split Heat Pumps and AC | for Ductless Heat Pumps, Window Units or Portable Air Conditioners, Control Remotely with Smartphone or Tablet, Energy Saving, Easy Setup Or Click on Amazon link here and search for what you need: https://amzn.to/3D1T2GQ This method is only applicable if you have Integrated Air Handler system. Ours are Alpine Home Air Armstrong AirFlow Oil Fired Furnace Model# LBR80C112/125D20-3A, with Honeywell Beckett Interrupted Ignition Oil Primary Control R7184B/102. A common split system is where the heating/furnace is in the basement and the cooling/air handler is in the attic, both sharing a single ductwork system and connected to an outdoor unit. A furnace provides heating, while an air handler (or the air handler's evaporator coil) works with the outdoor unit to provide air conditioning. To test for a live and common C wire, first, turn off power to your HVAC system at the breaker. Then, use a multimeter set to AC volts (\(200\) VAC range) to test for power between the R (red) wire and the C (common) wire. A healthy reading will be between \(24\) and \(30\) volts AC; a reading of \(0\) indicates no power, while a reading of \(0\) between the R and another wire (like G, Y, or W) could mean the C wire is not connected or there's a different issue.   A 5-wire system might not have a C-wire because older thermostats and HVAC systems in older homes were designed differently and didn't require a constant power source from a C-wire. Modern smart thermostats need a C wire for their Wi-Fi and features. The blue wire, often the C (common) wire, is not a ground wire but acts as a return path to complete the 24VAC circuit from your HVAC system's transformer. Reasons for a missing or why might not have C-wire in a 5-wire system: Older technology: Mechanical or battery-powered thermostats didn't need a continuous 24V power supply, which is what a C wire provides. Thermostat function: The other four wires (typically R, W, G, Y) control power to the heating, cooling, and fan components, but a C wire acts as the return path for continuous power to the thermostat itself. To repurpose a green "G" wire for a common thermostat, you must move the wire from the "G" terminal to the "C" terminal at both the thermostat and the furnace control board, and then use a small jumper wire to connect the "Y" and "G" terminals on the furnace board. This modification provides continuous power to the thermostat but sacrifices independent fan control, as the fan will now only run when heating or cooling is active. Background: Our house has a Honeywell T87 Round (mercury-based) Thermostat and we're planning to install Honeywell Home RTH9585WF. We took out the old thermostat and saw that we have 5 wires. This video is part of our mini-series on "Home HVAC Diagnosis, Repair & Fix it By DIY'er Aiman - Oil Furnace, Water Boiler & Rheem Central Air Conditioner (#Aiman_HVAC_Troubleshooting)". Here's the link to that playlist if you are interested:    • How To Bleed The Oil Line For Oil-Fired Fu...   This video is brought to you by Aiman-Imran Anuar. You can watch more of #Aiman_DIY_Fixit, #Aiman_HVAC_Troubleshooting and other videos with wide range of topics and themes on #EyeOnAiman Youtube Channel & Facebook Page. NOTE: This video is NOT sponsored. Some product links are affiliate links which means if you buy something we'll receive a small commission. As an Amazon Associate I earn from qualifying purchases. Recording Date: August 20, 2023 Video URL:    • How To Find Thermostat (C) Common Wire, Te...