Thermostat

It is difficult to see in the photo. Is there a wire connected to the Y2 terminal? Did you change the setting option to 2 stages of cooling? The default is one stage.

1. What is the brand and model of the OLD thermostat?
2. If you have access to the OLD thermostat installation manual, what is the purpose of the BK terminal at the upper right?

From this document page 4:

The DS/BK terminal is used with a variable-speed fan. If the HVAC equipment has DS, BK, ODD, or DHUM terminals, wire that terminal to the DS/BK terminal. When greater than 25% of zones are calling for cooling, this terminal will be energized and the fan will operate at normal speed. When 1 zone or fewer than 25% of zones are calling for cooling, the terminal will be de-energized and the fan will run at a reduced rate, which will reduce the amount of air that needs to be bypassed. This reduces blower speed on most variable speed blowers.

As discussed here, your new thermostat does not appear to support a variable-speed fan. Therefore, you must energize the black wire (which was connected to the BK terminal on the old thermostat) by connecting it to the RC terminal (which will receive power because it's jumpered to the R terminal). This will cause the fan to run at full speed (always).

According to the User Guide, page 29 you should configure the thermostat for two-stage heating and single-stage cooling.

-- amateur

Unfortunately, this did not work, no effect.

Hmmm. I'm kind of surprised, as jumping R to BK is the way the furnace was configured when there is NO thermostat control over the variable-speed fan as shown in Figure 63 and described in Note 9 in the Installation Manual. Maybe you should jumper R and BK on the furnace and ignore the black wire (?)

I assume that the thermostat yellow wire is connected to the furnace Y/Y2 terminal as described in Note 7.