Passenger side heater only works on high
blower motor resistor ?
My Corolla’s heater blower sports 3 speeds, works on the 2 highest speeds, but not the lowest. That speed failed after about 3 years. Pretty common problem on designs that use resistors to slow the fan speed. A 2017 Jeep may not use that technique though.
A somewhat related aside, I was recently doing some work under the my 50 year old Ford truck’s dashboard, and decided to see if I could find that resistor. I looked and looked, could never find it … lol … afterward I got to thinking it’s probably located inside the heater ductwork, that way the heat from the resistor helps heat the passenger compartment too. Plus it would tend to cool the resistor and make it last longer. It’s never failed on the truck.
When I encountered this problem in the past on my cars, replacing the resistor pack fixed it. I agree with @vipergg. Replace it and see if it returns variable fan speeds.
I have a 2015 Cherokee which has a dual zone climate control. If your does also there is a setting for the hivac which allows you to have different settings/temperatures, one for the driver (1 setting) and one for the front and rear passengers (2nd setting). For example, you can set the temperature for the driver at 75 degrees and the passenger setting for 60 degrees, so if you use the A/C on a 75 degree day, the driver side blower will not work because the ambient temperature is already at the setting, but the passenger blower will blow like mad to reduce the temperature from the ambient 75 degrees to the 60 degree setting. On the other hand, you can also set the system so both zones are at the same temperature.
I’d suggest before you go to the dealer/repair shop to have this sussed out you check your owner’s manual to see if you also have the dual zone climate control and to locate and check the settings.