Blower Motor Doesn't run

[VTRangeuh]

Been driving my 1993 ranger with the window down since the spring. About two days ago tried to turn the A/C on and nothing came out, no air from the vents. I checked the whole wiring path (doesnt seem there's a lot involved). Worked a week or two ago for the defrost.

There is the always on 10v from the battery present on one of the wires to the blower, and the knob seems to ground the correct wire. However, its like the supply can't push enough current, because it disappears to 0v once the motor is connected to ground. Motor works connected straight to the battery.

Only thing strange about the wiring is a quick-splice connector on the +12v wire which goes somewhere to do with the A/C I believe. The whole A/C system appears to have been replaced at some point because it takes r134a refrigerant and has a sticker saying it was serviced.

I've poked around and tested everything I could reach and it seems like maybe the wire from dash fuse panel to blower could just be bad? Maybe loose or something preventing it from drawing any real current. Nothing is shorted directly to ground as the fuse has not blown.

Two questions I suppose: 1) Where does that wire run from under the dash to the blower across the truck and 2) What else could cause this issue if thats not the problem?

 

[RobbieD]

Only thing strange about the wiring is a quick-splice connector on the +12v wire

That ain't good on a high-amperage circuit like the blower motor.

If the quick-splice broke any of the original wire's strands, and corrosion over time that always follows a quick-splice, when the fan demands high current to run the connection area fails as a conductor because of the load.

I'd pull off the quick-splice, check the host wire and repair if needed, and resplice the added wire (minimally, as a twist-and-tape).

I'd also pull the blower resistor block out of the HVAC housing, and check it over real good. Fan high speed should work even if the resistor coils are blown, but if the block or its connector have overheated enough, there could be a circuit failure there.

 

[ekrampitzjr]

It could be simply that the blower went bad, and it's under the hood. It's not unknown on Fords that vintage. I had to do that on a 1990 Ranger I had years ago, and soon after on the '98 Taurus wagon I had around the same time. Pulled replacements from salvage yards. The Taurus blower was under the dash.

Later I had to replace the blower on my dad's old Silverado. It was under the dash too.

 

[Curious Hound]

I agree with RobbieD. Check for problems at that quick splice. In my humble opinion, those things are dangerous snake oil.

Here is the diagram for the blower section of that system

 

[Uncle Gump]

This is one of the situations I love my power probe.

Connect it... and within one minute you can determine if the blower actually works.

But yeah... what everyone has said.

 

[Curious Hound]

This is one of the situations I love my power probe.

Connect it... and within one minute you can determine if the blower actually works.

But yeah... what everyone has said.

Motor works connected straight to the battery.

 

[Uncle Gump]

Details... I glossed right over that part.

Still love my power probe. I'm lost without one.

 

[VTRangeuh]

Yes ive seen part of the schematic and it seems that everything works except for the brwn/org wire. I have to charge the battery because obviously some power was going somewhere and it died overnight even with the ignition off. I probably should've run it after I troubleshot yesterday. While I do that I'm going to try and pull the crimp off. I dont like those things either and I'll fix up something a lot nicer to replace it. The cores themselves look alright. The wire was stripped way back to place the crimp on so theres actually a lot of exposed core. It could still be broken though.

And yes the motor definitely works, was like the first thing I checked with some clip leads. Once I found the connector

 

[VTRangeuh]

Okay so I removed the inline splice connector and it still has the same issue. Weirdly the voltage is lower than the battery (7-8v). Only one core is broken and I think that happened from my mishandling it trying to get that connector off.

Other weird thing to note, the spliced in wire is different from the factory one, but is still brown and orange. So it is color coordinated. I can't really trace where it goes though, and I'm trying to search for where the main supply goes. I tried my multimeter on amperage mode and I couldnt get any short circuit current over that wire, so I think its mostly broken somewhere.

New question: Is there any diagram of where the wires go in physical space?