Once youve located all the wires, taken a photo, and labeled where everything goes, its time to disconnect the wires and the mounting screws. W wires go directly to the source of heating; that may be a furnace (gas, electric, oil, you name it) or heat pumps ( mini-split heat pumps included ). Some types may use voltages as low as 6 volts or as high as 30 volts, but 24 volts is. This wire runs to the furnace control board which in turn controls the activation of the compressor and. Using the color of the wires as a guide, compare the wiring on your thermostat to the wiring on your system control board. You may use this as a reference for the purpose of each wire. O, B, O/B: These wires are responsible for switching the changeover valve in a heat pump system. The transformer steps down 120 volts. Most thermostat wiring bundles have 8 wires, though 10-wire bundles are also used on some systems. If your HVAC system is compatible, we can use an extra wire as the Common wire. Disconnect the Wires. Understanding the Terminal Letters on a Thermostat The Thermostat Is Dirty. To do this, use a wire nut to attach the red power supply wire to the green fan wire, then turn on the power. C wires or varying colors apply to every thermostat, but blue C wires belong to thermostats attached to a heat pump. White - The white wire is what connects to the (auxiliary) heat on your system. LpHdjNu6LpOfpyMqh73A- referrerpolicy=origin target=_blank>See full list on paspolini. The green wire on your thermostat connects to the fan of your furnace or air handler. When it is the only component in the system, you only need the red wire and white wire. Sensi Touch 2 smart thermostat. If no wire is connected to the C terminal carefully look in the wall cavity. You may find a c-wire connection and lead. This particular wire extends from the transformer and is responsible for completing the 24 V power circuit in the thermostat. Connect the wires from the control board to the outside unit. Wiring Diagrams Locate the schematic In most cases, a wiring diagram can be located inside the HVAC unit. Most of the time, the wire labeled B goes into the O/B connector on your ecobee thermostat and is used to control the heat pumps reversing valve, which switches between heating and cooling modes. Look for any wire that is tucked away behind your thermostat. Check all that apply (not all. Go to your furnace or heating system This system is often located in your basement, attic, or garage. In order to install that heat pump they would’ve had to install a new thermostat cable between the furnace and the outdoor unit which had at least three conductors. Where do the 2 blue wire out of the back of the furnace go. 2 Wire Thermostat Wiring. The G wire is green and connects to the fan. Seems that the 2 wires coming from furnace are carrying 12v and high enough amps to blow … read more. Boiler, Air Conditioner, Heat Pump, Furnace: Connectivity Technology: Wi-Fi: Included Components: 1 x C-Wire Adapter, 4 x Screw, 4 x Wall Anchor, 1 x Backplate, 1. The installation is complete now and the thermostat will be powered upon switching ON the power outlet. Where do thermostat wires go on furnace? The white wire underneath your thermostat connects to your heating system. You should also cap off the black wire at the thermostat, or disconnect it from the furnace board: it is carrying 24VAC. Most thermostats that control central heating equipment, including furnaces, boilers, and heat pumps, are low-voltage thermostats that typically use 24 volts of electricity. Usually, these wires are powered with 24 volts. Orange Wire For O And Dark Blue Wire For B (O/B Wire). W2 is designated for two-stage heating. She said the thermostat was replaced recently, but that didnt cure the problem. Connect the Wires Connect the red thermostat wire to the R terminal. If you have typical wires behind your thermostat, those wires must go somewhere. A) Remove cover from furnace or heating system. W, W1, W2: Just like the Y wire, the W wire (s) control the heating aspect of your system. Furnace 24 Volt Transformer. While many options use more than two wires, all systems will use at least 2. 2 wire systems are used for every thermostat and HVAC component out there. Common “C” wires are connected to the transformer and provide a continuous flow of power to the thermostat. The green wire underneath your thermostat connects to the fan of your furnace or air handler. The white wire connects to terminal W in industry-standard thermostats. This wire connects to terminal B. Most of your current thermostats wires will be connected to your thermostat and go through the wall to connect to your HVAC system. The common wire links to the C terminal. Thermostats use 24 volts AC from a transformer to control a furnace. Go to your furnace or heating system This system is often located in your basement, attic, or garage. In another image given below, you can see the same C wire going to the thermostat terminals side. This video is part of the heating and cooling se. Understanding Common Furnace Thermostats. Look for the wire connectors unknown wires attach to. The unconnected blue wire in the bundle needs to go to the c. How many wires does a furnace thermostat have? The most basic thermostat has 2 wires; usually a red and. Electric baseboard heaters and in-wall heaters may use line-voltage thermostats that use 120 or 240 volts of electricity. Using the color of the wires as a guide, compare the wiring on your thermostat to the wiring on your system control board. RH: The RH terminal is the 24-volt heating power supply. Note that only 24-volt wiring is covered: We do not cover 110/240-volt thermostat wiring and millivolt thermostat wiring issues. Many people can read and understand schematics called label or line diagrams. C wire from furnace to thermostat – Source. Where do thermostat wires go? Thermostat Wiring Tips The W wire is connected to your heating system. LEVOIT Smart Thermostat for Home, WiFi Programmable Digital Thermostat. C wire adapters are available here. Color of wire doesn’t matter it just color codes it for deciphering it from the thermostat and furnace, if your heat worked before there’s another issue that isn’t your wiring there looks of it the big white and big red look like they are probably connected to the heating relay. Simple Thermostat Wiring Guide (2,3,4,5,6,7,8 Wires …. If you’re unable to locate your HVAC control board or are uncomfortable doing so, please contact a certified HVAC technician in your area for additional assistance. The Y wire is yellow and connects to your air conditioning compressor. Find the transformer on the schematic Once youve located the. I can start the furnace by jumping the R and W wires on the control board. com/_ylt=AwrEbbv4m1dkh5A00EtXNyoA;_ylu=Y29sbwNiZjEEcG9zAzQEdnRpZAMEc2VjA3Ny/RV=2/RE=1683491960/RO=10/RU=https%3a%2f%2fpaspolini. Once you finish this connection, plug the transformer into your mains power outlet. Turn off the main power to your system at the breaker box. As the Pick HVAC Thermostat Buying Guide says about these thermostats. The most basic of systems (such as an older ‘heat only’ forced air / gas furnace with a standing pilot light) only need two wires for control. In some cases, one of those wires is your common. do you wire a honeywell thermostat to a furnace. Look for the wire connectors unknown wires attach to. Jumper the R terminal to the W terminal at the thermostat and see it starts the heat mode. If your thermostat controls your heat, you will have a white wire. This one covers the limitations of thermostat wiring that can be done with the oil furnace primary control. Green - The green wire connects to the fan. The common wire doesn’t have a standard color. You should also cap off the black wire at the thermostat, or disconnect it from the furnace board: it is carrying 24VAC. Where does blue wire go on furnace? The Blue or “C” Wire. How should the thermostat wires be connected to my furnace?. Of the Y, Y1, and Y2 wires, Y or Y1 go to the Y terminal and Y2 to the Y2 terminal. If there is any such wire, verify it as the common wire by examining the circuit board inside your furnace. IF the thermostat wire bundle routed to the thermostat included enough wires to operate all of the needed functions and IF the model thermostat includes both heating and cooling, the answer is probably yes. How to identify a thermostat wire. Identify a thermostat wire. Look for any wire that is tucked away behind your thermostat. Note that only 24-volt wiring is covered: We do not cover 110/240-volt thermostat wiring and millivolt thermostat wiring issues. This furnace houses the heating and cooling systems. Where do the thermostat wires go on the furnace? The white wire underneath your thermostat connects to your heating system. How do you wire a honeywell thermostat to a furnace. Locating the Required 24V Common Wire – Customer Support. 3 Method to Wire a Thermostat #1 Replace the thermostat wire for wire: #2 Locate the wiring connections in the furnace or air handler: #3 Use standard wiring colors to connect the thermostat: Common Thermostat Wiring Options – 2 Wire to 8 Wire Thermostats 2 Wire Thermostat Wiring 3 Wire Thermostat Wiring 4 Wire Thermostat Wiring. Typically, a furnace plus A/C HVAC system has four or five thermostat wires and a common wire. W, W1, W2: Just like the Y wire, the W wire (s) control the heating aspect of your system. As the Pick HVAC Thermostat Buying Guide says about these thermostats of alternate voltage: You might have to go to the air handler (could be a furnace) to locate the color of the wire on the Y terminal there. Your heater or AC won’t turn OFF Similarly, you can tell if your home thermostat is bad if your heater or AC don’t turn off at your command. Yeah the wiring looks correct, other than the red/white in the wall. Red wire to RH terminal on furance board and RH terminal on thermostat. The other cable is from your thermostat you have a red wire on R, a green wire on G, a white wire on W, a yellow wire on Y, and a blue wire on C. If a thermostat is thought to have a problem, then it can be bypassed with a jumper wire. Go to your furnace or heating system This system is often located in your basement, attic, or garage. Green Wire to G terminal on furnace board and G terminal on thermostat. 1 Answer Sorted by: 2 The blue wire at the furnace is likely feeding an airconditioner relay or something that was added later to the furnace. You may find a c-wire connection and lead. What is T1 and T2 on thermostat? L1 means line 1, L2 means line 2, T1 means Thermostat 1, and T2 means thermostat 2. Of the Y, Y1, and Y2 wires, Y or Y1 go to the Y terminal and Y2 to the Y2 terminal. A heat pump system, on the other hand, has eight or more different thermostat wires. Tap in the anchors, feed the thermostat wires through the hole in the base plate, set the plate back in position, and secure it with the provided screws. Familiarize yourself with the color coding for the wires. The two 24 volt wires go to the R terminal and C terminal inside the thermostat. If you cant find the c-wire or need help with the difference between a 4-wire thermostat and a 5-wire thermostat, call a professional electrician. Where Do Thermostat Wires Go on Furnace When you buy a new furnace or air handler, the wires that come with it usually have a white wire connected to it. It connects your thermostat to the air handler or furnace. Thermostat Wiring to a Furnace and AC Unit! Color. Most thermostat wiring bundles have 8 wires, though 10-wire bundles are also used on some systems. Thermostat Wiring to a Furnace and AC Unit! Color Code, How it Works, Diagram! AC Service Tech LLC 373K subscribers Subscribe 754K views 3 years ago. Your thermostat uses wires to transmit electric signals to your heating or cooling system at your command. The green wire connects to terminal G on your thermostat. Furnace Thermostats Wiring Starting on the upper right side of the diagram above: RC – Red:This wire provides 24 volt power from the furnace to the thermostat so that the thermostat can control air conditioning. While many options use more than two wires, all systems will use at least 2. Backup heat will typically switch on automagically depending on outdoor temperature. Most heat pumps include second-stage heating and require the white W2 wire. The HVAC control board is where the thermostat wires connect to your heating and cooling system. What All Those Letters Mean on Your Thermostat’s Wiring. Color of wire doesn’t matter it just color codes it for deciphering it from the thermostat and furnace, if your heat worked before there’s another issue that isn’t your wiring there You have two separate sets of wires coming to the stat…looks like the heating circuit rh and w you have placed the w on common this is no good. Black or Brown wire to C terminal on furnace board and C terminal on thermostat. Orange – This wire connects to. Red – Now, there can be two separate wires for this. Even though you won’t get any. Check your furnace to see if you have one. 118K views 9 years ago This one covers the limitations of thermostat wiring that can be done with the oil furnace primary control. Most of your current thermostats wires will be connected to your thermostat and go through the wall to connect to your HVAC system. Share Improve this answer Follow answered Dec 30, 2020 at 8:13 Ted Mittelstaedt 1,757 2 7. Why is my thermostat not getting power?. The other end of the white wire usually connects to the heating system in your home. LEVOIT Smart Thermostat for Home, WiFi Programmable Digital Thermostat, Works with Alexa and Smart Sensor, Energy Saving, Large Touch Screen, C-Wire Adapter Included, DIY Install, Aura 400S, White Visit the LEVOIT Store 114 ratings / 45 answered questions Deal -34% $9900 List Price: $149. the only other option is to pull more wires from the thermostat to furnace if you want to use a powered thermostat. However, if the low voltage wires touch each other during the work, the systems internal fuse will blow. This will be found on two-stage heat pumps, an aux heat system, or one that uses reversing valves that require power. Refer to the thermostat manufacturers wiring diagram for precise connection information. Where do thermostat wires go on furnace? The white wire underneath your thermostat connects to your heating system. Yeah the wiring looks correct, other than the red/white in the wall. Do not cut this or use the wall plug-in transformer if you have combined heating and cooling systems or a. The green wire on your thermostat connects to the fan of your furnace or air handler. Thermostat Wiring to a Furnace and AC Unit! Color Code, How it Works, Diagram! AC Service Tech LLC 373K subscribers Subscribe 754K views 3 years ago CAPE MAY COUNTY In this HVAC Installation. However, some thermostats will have a jumper wire that doesnt go back through the wall to connect to your system. White – The white wire is what connects to the (auxiliary) heat on your system. (meaning it uses R and C to complete a 24 volt power circuit) Reply. The best location for a thermostat is on an interior wall positioned near the middle of your home that is not affected by the following: Heat, steam, or moisture from a bathroom Drafty windows or doors Exposure to direct sunlight A neighboring cooling/heating register or grate Heat from a nearby appliance or from cooking. Instead, a short jumper wire connects two thermostat terminals together. Wire on a Thermostat (Beginner’s Guide!)>What Is the X2 Wire on a Thermostat (Beginner’s Guide!). Double-check the level before you tighten the screws all the way. Many older thermostats did not need c-wires, but they were available for use. What Is The Blue Wire On A Thermostat?. The orange thermostat wire links to your heat pump, if you have one. Option 1 – Connect an extra wire at the existing thermostat: Check your current wiring for extra wires the previous thermostat did not utilize. The furnace is a newer Rheem 80% (IFC, spark ignition) with A/C coil. How do you wire a Trane gas furnace thermostat? Wire a thermostat for a Trane furnace using these wire colors and terminals: Red to the R terminal for heating. Most of your current thermostat’s wires will be connected to your thermostat and go through the wall to connect to your HVAC system. Thermostat Wiring: How To Wire Thermostat? (2,3,4,5 Wire Guide). If you have a C wire, place it into the C terminal on your wall plate. In the modern thermostat, they have usually relegated these staging configurations and terminal designations into the installer setup, and every thermostat is a little different. The situation is the thermostat wont operate the furnace. Jumper the R terminal to the W terminal at the thermostat and see it starts the heat mode. It connects your thermostat to the air handler or furnace. Thermostat Wiring to a Furnace and AC Unit! Color Code, How it Works, Diagram! AC Service Tech LLC 373K subscribers Subscribe 754K views 3 years ago CAPE MAY COUNTY In this HVAC Installation. Thermostats use 24 volts AC from a transformer to control a furnace. This video is part of the heating and cooling series of. G: The G terminal controls the fan relay and is responsible for turning the blower fan on and off automatically or manually via the thermostat. Typically, a furnace plus A/C HVAC system has four or five thermostat wires and a common wire. At its most basic level, its simply a temperature-sensitive switch. Red - Now, there can be two separate wires for this. Green – The green wire connects to the fan. When testing the wires on the thermostat with a multi meter I still get zero volts. The ‘white’ color wire is part of the set that goes to the condenser unit. Where Do Thermostat Wires Go on Furnace. Look at the back of your thermostat and if the blue wire is connected to the thermostat’s C terminal you know that a C-wire is in place. Red wire to RH terminal on furance board and RH terminal on thermostat White wire to W terminal on furnace board and W terminal on thermosta Green Wire to G terminal on furnace board and G terminal on thermostat Optional wire for constant power to thermostat. The green wire connects to terminal G on your thermostat. Color of wire doesn’t matter it just color codes it for deciphering it from the thermostat and furnace, if your heat worked before there’s another issue that isn’t your wiring there You have two separate sets of wires coming to the stat…looks like the heating circuit rh and w you have placed the w on common this is no good. In most cases the control board can be found at your furnace or air handler. You may find a c-wire connection and lead. I just couldnt tell you where, or how they interface with your furnace. Orange - This wire connects to your heat pump (if you have one). However, on some thermostats, the wire labeled B is the Common (C) wire. Let’s look at the G wire. Wiring a Modine heater will require you to run an 120-volt electrical wire from a power source to the heater and a low-voltage thermostat wire from the thermostat to the heater. This one covers the limitations of thermostat wiring that can be done with the oil furnace primary control. However, some thermostats will have a jumper wire that. The fuse that’s in most furnace circuit boards is a 3-amp blade fuse. AC & Furnace Thermostat Wiring (Diagram & How To …. Furnace’s Control Board is Bad? Here’s What to Check. However, some thermostats will have a jumper wire that doesn’t go back through the wall to connect to your system. 6 Wire Thermostat Wiring. The unconnected blue wire in the bundle needs to go to the c terminal so both of them are connected there. Low-voltage thermostats are the most common and versatile type of thermostats found in homes. Thermostat Wiring Colors & Terminals Explained. The thermostat you see on your air conditioning unit is wired to a furnace. Thermostat Wiring to a Furnace and AC Unit! Color Code, How it Works, Diagram! AC Service Tech LLC 373K subscribers Subscribe 754K views 3 years ago CAPE MAY COUNTY In this HVAC Installation. If you can’t find the c-wire or need help with the difference between a 4-wire. A thermostat basically just energizes the individual circuits (G (fan), W (heat), Y (cool) ) which in turn (via the furnace controller) powers a relay which provides line voltage to the actual units (like the fan or A/C. A low-voltage thermostat typically runs on 24 volts of electricity and is powered by a step-down transformer wired to a standard 120-volt household circuit. C wire adapters are available here. This one covers the limitations of thermostat wiring that can be done with the oil furnace primary control. Most of your current thermostats wires will be connected to your thermostat and go through the wall to connect to your HVAC system. Thermostat C Wire: Everything you need to know about the common wire. Use the thermostat screen. Open the image of your thermostat wiring on your phone. Thermostat Wiring Guide (2,3,4,5,6,7,8 Wires Color Code)>Simple Thermostat Wiring Guide (2,3,4,5,6,7,8 Wires Color Code). 6 wire setups include using the C-wire and will be used on advanced heating systems with air conditioning. This is where you’ll see the RH and the RC wires. These wires are typically either blue or black and connect into the “C” terminal. Yeah the wiring looks correct, other than the red/white in the wall. The RH/RC jumper wire is located on the back of the thermostat face plate. Twist the black lead from your electrical wiring with the black lead on the heater. Where do the 2 blue wire out of the back of the furnace go. There are several steps you need to take to connect your thermostat to your AC unit: Disconnect the thermostat. This white wire is usually connected to the terminal W on your thermostat. Electric baseboard heaters and in. It terminates at your air handler or furnace. Bring a flashlight, labels, phone, and screwdriver. Yellow - The yellow wire connects to your compressor. Specific wires connect the thermostat and the heater to operate those systems. The line voltage feeding the furnace (to operate the fan blower motor) is transformed down to a safer level of 24 volts (the gas control valve needs 24 volts to open), and after making a series loop. Your thermostat uses wires to transmit electric signals to your heating or cooling system at your command. A) Remove cover from furnace or heating system Open the heating and cooling systems cover to find the control board. Double-check the level before you tighten the screws. Use a level to ensure that the wall plate is straight. If the fan comes on, this is a sign that your thermostat is failing to send the signal to the fan. R – Red:This wire serves the same purpose as the RC wire but for heating. Starting on the upper right side of the diagram above: RC - Red: This wire provides 24 volt power from the furnace to the thermostat so that the thermostat can control air conditioning. Where Do Thermostat Wires Go On FurnaceMost thermostat wires operate on 24-volt power provided by a transformer, and they are generally safe to work on without shutting off the circuit feeding the thermostat wiring. Tap in the anchors, feed the thermostat wires through the hole in the base plate, set the plate back in position, and secure it with the provided screws. Secure the wiring with an electrical clamp. 1 Answer Sorted by: 2 The blue wire at the furnace is likely feeding an airconditioner relay or something that was added later to the furnace. Vocational, Technical or Tra 29,324 satisfied customers. and could short out against one of the other wires. 6 Wire Thermostat Wiring. What Is the 4 Wire on a Thermostat. studio%2fen%2fhow-should-the-thermostat-wires-be-connected-to-my-furnace%2f/RK=2/RS=gMqYnF. In most cases the control board can be found at your furnace or air handler. The furnace thermostat is the nerve center of your home heating system. Where Do Thermostat Wires Go on Furnace. Extra wires may also be tucked behind the thermostat or in the wall, pull gently on the bundle of wires or shine a flash. 5 Reasons Your Thermostat Isn’t Working. Mark new holes to match the holes in the wall plate. The ‘black’ color wire is part of the set that goes to the thermostat. Refer to the thermostat manufacturers wiring diagram for precise connection information. O, B, O/B: These wires are responsible for switching the changeover valve in a heat. Check your furnace to see if you have one. How to Wire a Thermostat: 10 Steps (with Pictures). How To Connect Your Thermostat Wires to the AC Unit>How To Connect Your Thermostat Wires to the AC Unit. R (or Rh and Rc) provides the 24VAC power. G: The G terminal controls the fan relay and is responsible for turning the blower fan on and off automatically or. Most of the time, the wire labeled B goes into the O/B connector on your ecobee thermostat and is used to control the heat pumps reversing valve, which switches between heating and cooling modes. What is RH and RC on Thermostat? (Simple Answer!). But for all its mystery, the thermostat is actually a very simple device. 2 Wire Thermostat Wiring. Red wire to RH terminal on furance board and RH terminal on thermostat White wire to W terminal on furnace board and W terminal on thermosta Green Wire to G terminal on furnace board and G terminal on thermostat Optional wire for constant power to thermostat. Yellow – The yellow wire connects to your compressor. If it looks like there is a black puff of smoke in the fuse, then the fuse is blown. Wiring diagrams help technicians to determine the way the controls are wired to the system. Put up the replacement wall plate, if there is one. 3 Wire Thermostat Wiring. This means that you do have a c-wire, but you need to find the end of the lead near your thermostat. Compare the wiring at your control board with the wiring at your thermostat. The transformer steps down 120 volts to the 24 volts the thermostat needs, and sends out the 24 volts on two wires. In some cases, one of those wires is your common. Tap in the anchors, feed the thermostat wires through the hole in the base plate, set the plate back in position, and secure it with the provided screws. Blue wires are for heat pumps, like orange wires. and the other 4 wires most likely go to the AC Reply. RVIA Certification. – gregmac Apr 13, 2015 at 1:40 1 C and R on the control board are 24VAC. A C wire transformer has two output wires; connect one wire to Rc terminal and the other wire to the C terminal of your thermostat. This is one level of greater complexity and includes a C wire or Common wire connection. Typically, it will be on the inside of the access cover. The best location for a thermostat is on an interior wall positioned near the middle of your home that is not affected by the following: Heat, steam, or moisture from a bathroom Drafty windows or doors Exposure to direct sunlight A neighboring cooling/heating register or grate Heat from a nearby appliance or from cooking. The O wire reverses the valve from heating to cooling, and the B wire switches the valve from cooling to heating. Furnace Thermostats Wiring Starting on the upper right side of the diagram above: RC – Red:This wire provides 24 volt power from the furnace to the thermostat. It terminates at your air handler or furnace. Perhaps you connected the control leg to the wrong R terminal and actually need to install the required jumper between the Rc and the Rh as the old thermostat did. They can be hard to find, so make sure to look either inside the furnace or inside the wall. If a thermostat is thought to have a problem, then it can be bypassed with a jumper wire. Adding 24 VAC External Transformer in Place of C …. In some cases, one of those wires is your common. Green – The green wire connects to the fan. The common wire links to the C terminal. This one covers the limitations of thermostat wiring that can be done with the oil furnace primary control. 3 Method to Wire a Thermostat #1 Replace the thermostat wire for wire: #2 Locate the wiring connections in the furnace or air handler: #3 Use standard wiring colors to connect the thermostat: Common Thermostat Wiring Options – 2 Wire to 8 Wire Thermostats 2 Wire Thermostat Wiring 3 Wire Thermostat Wiring 4 Wire Thermostat Wiring. If you have typical wires behind your thermostat, those wires must go somewhere. An issue with these wires can cut off communication to your AC or furnace. They connect to a two-wire thermostat (generally a mechanical thermostat with a mercury filled ball connected to a coiled bi-metal strip). Open the image of your thermostat wiring on your phone. Where do the thermostat wires go on the furnace? The white wire underneath your thermostat connects to your heating system. The easiest way to tell if your circuit board’s fuse is blown is to look at the center area of the fuse. Thermostat for Home, WiFi Programmable Digital >LEVOIT Smart Thermostat for Home, WiFi Programmable Digital. Furnace Thermostat Wiring and Troubleshooting – HVAC How To. However, some thermostats will have. W wires go directly to the source of heating; that may be a furnace (gas, electric, oil, you name it) or heat pumps ( mini-split heat pumps included ). In order to install that heat pump they would’ve had to install a new thermostat cable between the furnace and the outdoor unit which had at. Option 1 – Connect an extra wire at the existing thermostat: Check your current wiring for extra wires the previous thermostat did not utilize.