It's been cold in Ohio! With our constantly fluctuating weather and humidity up here, it's been rough, using the truck for work out in the cold at night. I just replaced the heater core, since it was leaking. I had a smell of coolant when firing up the heat, followed by foggy windows! I got a new core installed, but now the heat seems to work maybe 30% of the time, and usually not at night when it's colder out and it's desperately needed. Both hoses coming off the core seem to be heating up enough, and the blower door actuator seems to be working and sounding fine. My engine temp seems to warm up normal as well. I also changed out the blower motor resistor and pig tails for it, because the fan only works on high, but that problem was not solved either... So I ordered another fan/temp switch for a 1998 ranger from washington(not a part easily found new at a reasonable price) But the fan still only works on high. I have checked fuses, and they also seem in order, but I might pop in some new ones just to see if anything is solved, it would be nice to at least be able to set the fan on a lower setting, while the truck heats up so that the air can also heat up more efficiently and not cause something else to have problems in the long run. My mechanic has advised me that my water pump's weep hole has a leak, I have just ordered a new water pump and seal to be installed on Saturday. But I just went out to the truck, after making a trip to class, which is a normal 10 mil drive, while hitting the freeway, so it definitely heated the engine up sufficiently. When I got home, I started playing with the fan/temp controls, to look at the switch, located just above the two hoses coming off the heater core, and slightly pushed it closed, and I got some lukewarm heat. After about 5-10 minutes of letting it sit in my parking lot and going back out to check on the heat coming out, it actually felt, relatively warm! And I kept switching it from Max A/C to regular heated fan, and looking at the switch, and it seems to be opening/closing. Although now when switching to A/C I didn't notice the air cooling down. What is that switch that opens/closes when changing from A/C to fan even called? And is it possible that it is getting stuck/needs replaced? Help please!?

 

Sounds like a blend door motor to me.

 

Is the blend door motor the round cylindrical small piece next to the blue freon cap?

 

I don't hear clicking or anything when I turn the heat on or switch to A/C, and I do hear normal change in airflow, though.

 

No I have no idea what that gizmo is sorry.