Nest Thermostat blowing cold air

[Noob122021]

Just installed the NEST thermostat a couple of days ago. The old thermostat was working just fine and the furnace hasn't had any issues at all. Once the NEST was installed, it only blows cold air when set on heat. I've posted how it was wired with the last thermostat and how it's wired with the new NEST. Can someone assist? 

• 

   

  

   

[Houptee]

You can take a piece of wire and with Nest pulled off jumper R to W and heat will turn on.

If it does not turn on when jumped you might have told the Nest wron info about the system when you set it up.

Just tell it you had wire on Rh only not Rc because your old thermostat had a jumper switch on bottom that connects Rh and Rc so just tell Nest you only had wires on Rh W C Y G

[Noob122021]

Isn't the jumper from RC to RH?

I've jumped W to R and deleted/re-added the thermostat. Still blowing cold air. 

[Noob122021]

 

[Noob122021]

Also did Rh only, but it then says the system isn't compatible. 

 

[Houptee]

If the heat is not kicking on with the jumper from R to W you might have blown the fuse in the furnace for the 24V power. There is sometimes a automotive style fuse on the board.

[Houptee]

With Nest removed test for AC voltage with a multi meter from R to C should read around 24 v AC not DC.

Do not install Nest with the jumper wire installed that is only to test the system.

The jumper puts power from R directly to W it should force heat to turn on without a thermostat (the thermostat is basically just a switch that puts power from R to W for heat, and G for fan, or Y for the AC).

[Houptee]

If you did not turn off the power when you wired the Nest you might have blown the fuse on the furnace board or some use a small circuit breaker that can be reset near the board in the furnace. Or possibly the transformer got damaged if the fuse is good and you do not read any AC voltage from the transformer.