1999 explorer fan blower problem

[C420sailor]

I’d be impressed if you did it without. It was a minor pain even with it removed. Only one bolt anyway.

 

[donalds]

I removed the CC and washer jug the plug was the hardest part

 

[MakinJeepsWeep!]

Alot of times the plugs are half melted happens on almost all vehicles I've found.

 

[J_C]

Guess I'm lucky that mine wasn't melted at all, though it makes me wonder, if you put silicone grease on it to help with weatherproofing, would that transfer more heat to the harness connector? On the other hand, taking MakinJeepsWeep for example, he's in TX where it gets hotter in summer so the air past that module is hotter.

Was it only the resistive (or transistor) module molten or was the harness connector molten too?

 

[MakinJeepsWeep!]

Mine on both the 96 X and 01 b3 looked like the resistor is what got hot and started to melt in turn melting the plug and harness less so. Also good point here 90% of the time fans are on full blast high amp all the power and heat since replaceing them I see no signs of it happening again. So I thought that with age resistance went up in turn extra heat causing the melt down.

 

[J_C]

^ Yes as those crimps on the resistive wire elements on the module degrade, the resistance increases, but that does not increase the total amount of heat produced since there is also less power going to the blower as a result. With less power going to the blower, it blows less air past and that allows more heat buildup.

Full blower speed bypasses all the resistive elements so produces the least (almost no) heat with the most airflow, would make the module last practically forever, but then the fan running at high speed all the time, not so much. They could have designed this better, but pennies saved here, pennies saved there...

 

[MakinJeepsWeep!]

I stated that in correctly, I mean in the since for example high load on a extension cord and plug/cord end gets hot. Resistor pack plug harness cord. Might still be wrong just what I was thinking.

 

[CDW6212R]

Mine on both the 96 X and 01 b3 looked like the resistor is what got hot and started to melt in turn melting the plug and harness less so. Also good point here 90% of the time fans are on full blast high amp all the power and heat since replaceing them I see no signs of it happening again. So I thought that with age resistance went up in turn extra heat causing the melt down.

I think it's the hotter climates where the fan is run on high or almost full blast a lot of the time, where the current eventually kills the blower resistor, followed by the connector.

My 95 Crown Vic is like that now, I changed the resistor but the connector looked rough too. I need to cut and replace some of those wires I believe, I bought the connector pigtail a while ago. It occasionally only runs in high and not speeds 1-3(those have two circuits in the blower resistor device).

 

[MakinJeepsWeep!]

Mine was the same 1-3 iffy high worked

 

[C420sailor]

Well, that lasted about a week. Back to its old tricks.

I doubt the Motorcraft resistor went. What next?

I think I need to check the orange/blk at the resistor. And I’m not sure what the thermal limiter in the resistor is, hopefully that didn’t blow out.

 

[J_C]

^ I thought that thermal limiter was supposed to be a resettable thermal breaker, that should conduct again once it cools down (but only a finite # of times, they don't seem to last nearly as many reset cycles in other applications, as I've seen suggested they should on datasheets), though they also make one-shot fuses with a similar component shape. You can use a multimeter on its leads to check continuity.

When the blower should be running, there should be 12V on the pink/white wire to the motor relative to chassis ground. If there is not, you either have a blown fuse (#2?) in the power dist box under hood, a bad blower motor relay, or a bad console switch failing to ground the relay. I'm ignoring wiring faults, bad wire or severe contact corrosion between any two points in the circuit can be a cause too.

If there is power getting to pink/white wire to blower, or the fuse is blown (and then replaced), and shorting the brown/orange wire from the motor to chassis ground does not run the blower, then you probably have a bad blower motor... might just be a seized bearing, you could try lubing it and rotating the squirrel cage to position the motor brushes on a different section of the commutator to see if it'll start, but if that's the case it may be worn out. You can also measure for power all along the circuit, diagram attached.

 

[C420sailor]

The fan still works, only on high.

Per the schematic, high bypasses the brand new resistor unit.

I have a replacement thermal fuse on order, and a Motorcraft fan and wheel. I’m thinking the original fan is just pulling too much amperage in its old age, and cooking thermal fuses. I’ll replace the motor and solder in a new fuse and see how long she runs.

 

[Pete Deering]

A while ago my fan blower quit working and only worked on high speed. Recently, the highest speed quit working as well. I've done some research and narrowed it down to a few possible factors that may be wrong such as resistor, fuses, or the blower motor itself. Can anyone help pinpoint the problem before I start tearing things apart?

On my 95 xlt , I only had high and low speed. The problem was the connector at
resistor, the plug that plugs into the resistor can get pretty rusted to the connector. After separating the plug. I could not remove the F connectors inside the plastic plug. So I used rust converter inside a zip lock bag, and soak the connector in the solution. Installed the new resistor added silicone grease die-electric grease too the connector. You mIght have two problems. YoU can Provide power too the blower motor to see if it works. My Blower motor is a replacement. I removed the pass side inner wheel liner to allow access to everything made easy. If you have that connector tool, you can remove the connector, which I did not have at the time

 

[J_C]

Not knowing how hot that breaker gets, I'd try to use a brass crimp instead of solder if not too much trouble to do so, for example if you had some brass material left over from some failed appliance or whatever (I cannibalize various materials for such situations), or if not, nothing's going to happen if the solder fails except it loses the speeds again, so will have to pull it out and try over.

Then again if you can read the markings on the breaker, they should indicate the trip temperature which tells you how hot before it goes open circuit.

 

[MakinJeepsWeep!]

Something does not seem to be adding up to me. I could have swore that my blower resistor had one for each speed, You could clearly tell that with each speed the coils and size of coils changed per speed set in turn changing the power the got changing its speed. Now in a Chevy i did recently it did in fact bypass the resistor completely with a relay for the high speed to the side of it. Again im no expert here the vehicles i have are the first ones i have bothered to have ac in because once you have it you cant go without it.

 

[C420sailor]

In the resistor module, each speed has its own respective coil of resistive wire, but they all then flow through the same thermal fuse. Once that thermal fuse pops, you lose all three non-high speeds. Since high doesn’t pass through the module, just straight to the switch, it continues to function.

Parts arrive this coming week, will advise.

 

[C420sailor]

Aaaaaaand now it’s totally dead. 324,000mi is a good run. Should have a new Motorcraft motor and fan installed today...and we’ll see if I can fix the resistor

 

[C420sailor]

Should be fixed for good now.

Removed the airbox, coolant/washer tanks, and cruise control. Removed the four screws holding the blower motor in, removed and unplugged it. Removed the blower motor resistor (that I just replaced two weeks ago...ugh).

The bearings/bushings were shot. It had noticeable drag/resistance when you tried to turn it. I think this resistance was causing the fan to pull a lot of current, which overheated the thermal fuse in the resistor assembly, causing me to lose all speeds but high. Eventually, I think the bearings got so bad that the blower motor wouldn't turn at all.

I took a peek at what I could see of the AC evaporator coil. DIRTY. Never been cleaned in 324,000mi. I got a hose in there and flushed it out the best I could, and the box drained nicely.

I installed a new Motorcraft blower fan and a new fan blade from Continental. This was the easy part.

I didn't want to buy another blower fan resistor because the one in there was brand new, and only had a blown thermal fuse. I ordered a Radio Shack #2701320 139*C thermal protector fuse, which is only a few degrees lower than the OEM fuse. Close enough, I figure.

Checked, and sure enough, the thermal fuse was blown. No continuity, while the new one had continuity.

Changing this...sucks. I initially planned to solder it, but I was concerned the heat from the iron would blow it out. I managed to use a pick and small screwdrivers and such to remove the old one, enlarge the crimp holes, and insert the new one, and re-crimp it with pliers. I was only able to engage one hole on each side, but it felt pretty solid. We'll see how long it lasts.

Works like a champ now!