How To Bypass The Thermostat: Step By Step Guide

bypass thermostat

The thermostat is an ac component that controls the heating and cooling by opening and closing your AC. If your thermostat is bad your ac will not do any cooling or heating. You can try to bypass it to see if there is a problem with the thermostat or not.  

How To Tell If An Ac Thermostat Is Bad?

If your ac is not turning On and you think it’s the thermostat. Then you can just remove the thermostat and try bypassing it with jumper cables. If the AC turns on then your thermostat is malfunctioned or bad. To bypass the thermostat just follow the below step-by-step tutorial.

Thermostat Wires Explained


The thermostat terminal will be labeled as. 

G = Fan

Y= Cooling

W= Heating

R= Power

Rc= Power to Cooling

Rh= Power to Heating

C= Common

  • The Red wire (R) is going to be your power wire (24 volts) which sets into the R socket of the thermostat. If you have Rc or Rh then you want to have a jumper between R and RC or R & RH. Because R means power and RC means power for cooling. So if you don’t have any power going to cooling then your AC won’t be turning on.
  • Y is yellow and it’s for cooling and it’ll set into the Y socket of the thermostat.
  • G (Green) is for the fan (the blower fan) in the furnace or air handler. The green wire will set into the G socket of the thermostat. 
  • W or white is the heating. The white wire will set into the W socket of the thermostat. 
  • The blue wire is for common and it’ll set into the C socket of the thermostat. 

Note: Just so you know even though this is standard color coding. There are thermostats out there that don’t go by this code. So in that case you can do is just click a picture before removing the thermostat wiring. That way you’ll know which wire goes into which socket.

How To Bypass The Thermostat In AC?

Step 1: Turn Your Furnace Power Switch OFF

The furnace switch looks like a light switch you need to turn that switch OFF. Because this switch passes current and you don’t want to get shocked.

Step 2: Take Your Thermostat Cover OFF

The second thing you need to do is take your thermostat cover off. You can do that by different methods because different thermostats have different structures. It can have two or more screws you’ll need to take that off or it can have clips you’ll need to pull them off or just pull the thermostat off.

Step 3: Then bypass the thermostat with Jumper cables

You’ll need a pair of jumper cables (you can buy magnetic or alligator jumper cables). If you don’t have a jumper cable you can just do it with a piece of wire. But to be on the safe side use jumper cables. 

So the thermostat will have a fan switch, a cooling switch, and a heat switch. So in the summer when the temperature gets too high that switch automatically oops up and it turns on the AC, in the winter same deal with the heating, and for the fan.

If you set the fan setting to on that’ll flip that switch on as well. So basically what we’re doing with a jumper is manually turning on those switches. 

Bypass the thermostat and Turn the AC ON:

So first you’ll need to put your jumper cable on the ‘R’ i.e the power. And then put the other end of the jumper cable to ‘Y’ i.e for cooling. And after this turn, your furnace power switch On and this way your AC will turn on and start cooling. If nothing happens and AC doesn’t turn on then you know that your thermostat is not the problem.

Bypass the thermostat for Heating:

So for heating, you’ll need to connect one end of the jumper cable to the R and the other to the ‘W’. If you have R and Rh terminals at the thermostat.

Then you need to put a jumper in between those two terminals. Most of the time ac heating is not working because there is no jumper between these two terminals.   

And similarly, you can do for the fan one end to R and the other to G.

How To Bypass The AC Thermostat At The Control Board?

Step 1: Turn the furnace switch OFF.

Step 2: Open Your Furnace door and access your control board.

Step 3: If you want to turn your ac On. Then connect one end of the jumper cable to the R (power) and the other end to the Y(cooling).

Now if you want to jump for the heating you can jump from R to W and for the fan R to G.

Remember if you are using a jumper cable to Turn ON the AC then it’ll run continuously because you have bypassed the thermostat. Once your house is cooled enough just remove the jumper cables. 

Check Our Article On Most Reported Problem By AC Owners

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