this is correct, the heater control valve is located on the passengers side of the vehicle, mid-way down that side of the radiator, that does control the heat problem you are experiencing . i had to replace mine , it is simple to d.i.y. though time consuming.
i bought mine from my dealership, and it took about 3 hrs to remove and install.
i do hope this helps . keith.
Source: master mechanic, and car owner.