So, got another problem right after fixing a couple others. Burnt smell and low airflow. I'm 99% certain the blower motor resistor is the culprit (picture below) but wanted to get other opinions.

Problem: Air vents now have very unreliable airflow, usually quite low but sometimes go to ~50% of normal capacity. There is usually a burnt smell coming from them. At first, it was similar to the undercoating oil spray (I get Krown every fall), but switched to a more burnt metal/plastic smell that has remained consistent. Almost no airflow from passenger-side vent beside the door.

Other information: Blower motor was replaced in the winter. I removed the blower motor and there was no debris inside it, or the tubes connected to it. There was some debris behind the screen separating the cab and the engine compartment, but not a lot; I took a leaf blower to it from the engine side and some blew out onto the passenger side floor. Resistor looks extremely corroded. Replaced some of my front head lamps & signals and the flasher relay a few days ago; may or may not be related, hell if I know.

 

Yes, that resistor block could be replaced without fear of wasting money
You must live in a fairly humid climate, lol.


Just as a heads up
The Vents in the cab are controlled by Vacuum, defrost, panel, floor, and then outside air and inside air vent
Defrost is the default, no vacuum, setting for the doors inside the system
If you are accelerating and feel the vent selection shifting from Panel to Defrost vent then you have a vacuum leak in the system or a leaking Vacuum reservoir

 

Yup, Ontario. It's also original afaik, so 12 years old now?


Yeah, I had default-only issues before it stopped entirely when I replaced the motor. Air still comes out the correct vents, just very little of it.

 

There is no vent door that will block air flow from the fan, just changes its direction

Diagram here: https://www.explorerforum.com/forums...iag-gif.41768/

Air flow starts on the right, at the fan/blower, it has a dual intake, outside air is default, inside air is used in MAX AC only, if you switch to MAX AC and air flow increases then outside air vent is blocked up, its under the cowl and hard to access

Fan blows the air through the Evaporator(AC) and into the cab through a hole in the firewall
Where it encounters the Blend door, this is an electric door, not vacuum, its controlled by the TEMP ****, it directs air flow through the heater core(HOT) or around the heater core(COLD), or anywhere in between to adjust TEMP of the air, so it splits air flow but doesn't block it, if air flow is less with TEMP set as HOT then could be heater core has some debris partially blocking air flow.

The remaining 2 vent doors, panel/floor or panel/defrost have no "working" positions that could block/reduce air flow out a selected vent direction, these just direct flow

Rangers/Mazda B-series had no Cabin Air Filters like other Ford Models, just FYI

 

Sorry, I was not being clear. The passenger side vent does not block any airflow, it's just that this vent had less airflow than all the others, even the driver-side door vent.

 

Try closing the other vents and see if the low flow vent gets better air flow, if not then it has a blockage, for sure

 

I can only close the door vents, the centre vents cannot be shut.

Well, I replaced the motor resistor, and I'm still getting a burning smell and lower airflow. I think I'm gonna have to bring it in to a mechanic to take a look.

 

Update: Fans are no longer functioning. Faint hissing noise if I try to turn them on. They were working earlier, but max speed and max A/C would turn off. Shortly after that, all settings no longer work, and the only air is intake air while driving at speed. Will be checking the fuse shortly.