Hello I'm new to the forum. I have been searching for hours and can't find anyone with the exact same problem as me, but I found many similar issues.

I have a 2007 Ford Ranger. I can't get any heat through the vents, in any of the selector switch positions, or any position on the hot/cold selector.

Also, unless the vent selector switch is in the off position, the AC engages, and blows very cold air. it seems that no matter what I choose, it always blows as if it's set at the coldest AC setting, even when I have the heat setting cranked.

I have checked my heater core hoses at the firewall, and they both feel like the same temperature (hot). The "heater control valve" plunger moves in and out when I turn the heat on and off, so it seems fine. I have also checked several of the fuses (in both fuse boxes, under the hood box and interior passenger side box) and they seem fine. I also topped off the coolant for good measure.

From the info in the similar threads I found, I am suspecting it could be a problem with the blend door or blend door actuator. Could anyone suggest a method of diagnosing this type of problem? I would like to get an indication of the source of the problem before I start swapping out parts.

I'm sure I'll think of more details soon, I've been testing a bunch of different things.

If anyone has any suggestions for diagnosing or troubleshooting this type of problem, I would appreciate it.
Thanks
Chris