Intermittent, Now Fully Non Functioning Blower Fan, 2002, Soon to Be Popsicle

If you don't wish to become a Popsicle then it would seem like a good idea to replace the blower motor...

To confirm that the motor is the problem, see if you can remove the cabin air filter and reach down to the blower. Then spin it while the fan switch is turned on and see if the blower will start to spin. If so, that is more evidence that you need to replace the blower motor.

 

I think if it were happening to me I'd just have to pull out a multimeter and start figuring out where voltages were and weren't. What you describe might be consistent with a loose or corroded wiring connection somewhere, maybe a faulty motor as Patrick suggested, or even the driving circuitry on the A/C amplifier module. I can't think of any obvious shortcuts to finding out what's really at fault.

Hobbit learned a lot of details about the fan control circuitry, though I think he was working on an NHW20 and I'm not sure if much is different about the Classic.

-Chap

 

Good find. That connection is likely providing power to the blower fan.

Perhaps the wiring harness connector was not fully inserted into the mating socket. Or there may have been a defect that took time to manifest itself.

The "correct" approach would be to replace both sides of that connector, but this requires being able to source those parts. Perhaps they could be obtained from a salvage yard.

An alternate approach would be simply to cut off the connectors, solder the wires together, then apply electrical tape to the uninsulated solder joints.

 

Good job tracing the fault. As for what may have caused it, my first answer is just "it can happen". The blower motor can draw fairly heavy current and if that particular female terminal wasn't formed with quite the tightest springy bends out of the carton of terminals they used that day, it might have run warm over time. Heat accelerates corrosion, so over time it got worse. You don't need obvious water dripping on the terminal, just humid air in the footwell when people get in with wet boots etc. Without the book in front of me I'm guessing that was the + terminal, which usually takes the brunt of green corrosion if it's going to happen.

If the blower motor has a problem where it runs but draws excessive current, that could also have caused the terminal to run warm. You can check that with an ammeter after you've got things back together, but my first guess is it just wasn't the tightest of terminals originally, and you should fix it, enjoy your comfy warm car, and not fret over it.

If you have the wiring diagram manual, the connectors in question will be called out with a letter and number, which you can match to the lists of connector shell and repair terminal part numbers in the back of the book. Last time I checked, the dealer seemed to sell the repair terminals only pre-crimped to a short length of wire so you can cut out the original wire a few inches back and splice in the repair. I would replace both involved terminals (i.e. the male and female for that side of the circuit, in the blower connector and the wire-harness connector). If the other two look good there's probably no need to fuss with them. Whether to replace the connector shell with the discolored spot probably depends on whether it just has a cosmetic spot, or got hot enough to melt and lose shape at all. If a new terminal goes in with a nice click and sits straight and even with the other one, the shell is probably usable if you don't mind the black spot.

-Chap

 

According to my book (2001) you'd be looking at connector B6, which is part no. 90980-10214 for the shell. Last time I did this was a while ago; I remember now that the book doesn't list the part numbers of the terminals that go in the shell, but your dealer parts guy has a list, give him the shell part number, he can look up the terminals.

I also remember that my dealer told me they could only sell the terminals in "repair terminal" form with a bit of wire the wrong color already crimped on, but then I stopped in my local indie auto electrical shop and he said he often gets the terminals plain, and he gets them from the same dealer I had just come from who wouldn't sell them to me. Guess he just talks to somebody I can't get to from the parts counter.

The connector it mates with might only come as part of a blower motor assembly, p/n 87103-47020 according to toyodiy.com, but you might still be able to take it apart enough to replace the terminal if you can get a terminal.

-Chap

 

... I confess I'm also not above adding a bit of Ford's electrical grease to a contact that I want to stay low-resistance and uncorroded ... that's their electrical grease, mind, not their dielectric grease which would be kind of the opposite of what you want (though it does also lubricate brake parts).

-Chap

 

Depends upon what "little warm" means. I'd say that if the temp of the connector exceeds 100 degrees F then you should replace it.

Electrical grease is formulated to improve conductivity. Regular grease lacks this and will not help. See for example:
Sanchem NOOXID electrical grease & electrically conductive grease dielectric grease and contact lubricants

The AC compressor will run as needed to cool the passenger cabin.

 

The reason for using dielectric grease on a spark plug boot is to discourage the rubber boot from fusing on to the spark plug porcelain tail. This also will retard the formation of corrosion on the high voltage terminal within the spark plug boot.

I learned first-hand the consequences of not having this grease applied, when changing the spark plugs on my 1997 Ford Explorer V8 AWD several years ago. It was necessary to go through the front wheel wells to access the plugs. The spark plug boots had fused to the spark plugs so I had to replace the spark plug wires. While trying to yank one boot off its plug, I scraped a few inches of skin off my forearm (which rubbed against the metal wheel well opening into the engine compartment.) Too bad I wasn't wearing a long-sleeve shirt...

 

I believe that the blower fuse is 30A. That is a pretty large size, so there can be at least 420+ watts of power flowing without popping the fuse.

I suggest you run the fan for 30 minutes at high speed and then feel how hot the connector is. It probably won't get hotter than that temp.

 

The fuse only reacts to the amount of current flowing in the circuit, and it is sized to blow at a current that could cause dangerous heating in the wires themselves. If the circuit has any local region of higher resistance, like that bad terminal, that region can get plenty hot on less current than it would take to blow the fuse.

An example: your kitchen probably has some receptacles on a 20 amp breaker. The breaker is 20 amps because more current than that would excessively heat the 12-gauge wires inside your walls.

One of those receptacles probably has a toaster plugged into it. When you use the toaster, it probably draws maybe 8 amps. Nowhere near enough to trip the breaker or make the wires in the walls even feel warm, but the higher-resistance wire inside the toaster is glowing orange hot. In the case of a toaster that's what you want; for a connector terminal it isn't, but the fuse or breaker can't tell the difference.

-Chap

 

Well, the Motorcraft part number I linked to is probably good at your friendly neighborhood auto parts job shop, or your nearby Ford dealer. The No-Ox-Id link from Patrick is probably something you'd find at the local electrical supply. and is probably equally good.

I think the "bulb grease" I've seen reminded me more of the silicone dielectric grease (the other link I posted), and chiefly has the effect of making it easier to unscrew the bulb later rather than improving conductivity much. But I'm not sure what it really is.

The dielectric grease is great stuff, too, for a lot of applications, though not what I'd use for this one. Besides lubricating brake parts and keeping spark plug boots removable, it's a fantastic lube for radiator/heater/vacuum hose fittings - in unbelievably small amounts, like just lightly tap your fingertip on the open end of the tube and wipe an imperceptible layer on the fitting, then slip the hose on noticeably more easily ... and best of all, 5 years later if you need to, loosen the hose clamp and slip it back off. I've also seen pretty much the same stuff sold in hardware stores as silicone plumbers' grease and used to keep rubber faucet washers and O-rings slippery. But for your blower terminal I'd stick with electrical grease especially made for conductivity.

-Chap