The valve is located in the compartment below the buddy seat. Raise the seat and pull out the plastic container. Then you will see the valve. It is operated with an electric motor and you probably need to replace it. Not a bad job.
Where would I find the cab heater valve on a 2166 My AC works fine but when I switch to heat I get nothing. On occasion last year if I kept messing with it, it sometimes would start to work. I replaced the switch. The hoses coming off the engine are hot.
Thanks for any advice. Wet corn and green beans.