1995 Bronco Heater / Air Fan speeds

[Pamm]

Ok my bronco sat a while and Now I am working hard to get back in A 1 shape. My fan only runs on high now. It that in the switch or the fan ???

 

[Skitter302]

Sounds to me like your resistor kit is unplug'd or damaged.​

1987-1997 Ford Bronco and F-Series Truck Blower Motor Resistor Kit​

1987-1997 Ford Bronco and F-Series Truck Blower Motor Resistor Kit-Broncograveyard.com

250 degree thermal limiter, for factory ACbr or NON AC trucks ot broncosbr Enggineered from high quailty materials to effectively withstand the condensation that typically causes corrosion in resistors. The durable design resists thermal fuse failure, overheating and burnout.br Restores heating...

shop.broncograveyard.com

 

[miesk5]

Yo Pamm,
As Skitter advised.
Blower Motor Resistor:


It shows where leaves build up in 80-96 ductwork. , If they build up around the resistors, the Bronco can catch fire if the blower motor is NOT at full speed all the time.

Blower Motor Switch Resistor Assembly
Removal
Pry the wire connector from the heater blower motor switch resistor (18591).
Remove the two screws that attach the heater blower motor switch resistor to the heater plenum chamber case (18A484).

Installation
Follow removal procedures in reverse order.
Check operation in all blower speeds
To test the blower heater blower motor switch resistor as well as the internal thermal limiter, check continuity for shorts or opens with a self-powered test lamp. If the unit indicates an open or short, it cannot be repaired and will require replacement.
●

PINPOINT TEST F: BLOWER MOTOR OPERATES IN HIGH SPEED ONLY​

F1 CHECK BLOWER OPERATION

• Key to run, function selector **** to FLOOR and blower **** at LO.

Does blower motor operate?

Yes	No
GO to F5.	GO to F2.

F2 CHECK BLOWER SWITCH HIGH SPEED​

• Slowly move blower **** from LO to HI. Stop at each detent and check for blower operation.

Does blower motor operate in any speed except HI?

Yes	No
GO to F4.	GO to F3.

F3 CHECK GROUND CIRCUIT​

• Check Circuit 57 (BK) from heater blower motor switch resistor to ground for an open.

Is ground wire open? miesk5 Note; it's a Black wire.

Yes	No
REPAIR and/or REPLACE as required.	REPLACE heater blower motor switch resistor.

F4 CHECK CIRCUIT​

• Check Circuit 261 (O/BK wire) between blower motor and heater blower motor switch resistor for open.

Is circuit open?

Yes	No
REPAIR as necessary and CHECK blower motor operation.	REPLACE heater blower motor switch resistor.

F5 CHECK BLOWER SWITCH​

• Check blower motor operation several times in each blower **** position.

Does blower motor operate in all **** positions without interruption?

Yes	No
CHECK system operation in all function positions and blower speeds. If OK, INSTRUCT owner on correct operation of system.	GO to F6.

F6 CHECK BLOWER SWITCH CONTINUITY​

• Remove harness connector from blower switch and check continuity through switch in each position.
• 
  TEST PROCEDURE
  

  Switch Position​	Continuity Between Terminals​
  Low​	B​
  Medium 1​	B + D​
  Medium 2​	B + C + D​
  High​	B + A + C​

  

Is switch continuous in all positions?

Yes	No
CHECK continuity of Circuit 754 (LG/W) and Circuit 752 (Y/R) between blower switch and resistor assembly. REPAIR as required.	REPLACE heater blower motor switch.

●

Lastly, the red pointer is where the rubber cowl drain boot should be under passenger side Fender, near door. I reach up in opening with my fingers to feel for debris and to remove.

 

[Motech]

A faulty or disconnected blower motor resistor is the only thing that causes high speed only. Don't even bother testing. If the resistor pack is plugged in, just buy a new one for 12 bucks and consider that your test and fix at the same time.

 

[miesk5]

A faulty or disconnected blower motor resistor is the only thing that causes high speed only. Don't even bother testing. If the resistor pack is plugged in, just buy a new one for 12 bucks and consider that your test and fix at the same time.

Yo,
Incorrect.

F3 CHECK GROUND CIRCUIT​

• Check Circuit 57 (BK) from heater blower motor switch resistor to ground for an open.

Is ground wire open?

 

[Pamm]

Yo Pamm,
As Skitter advised.
Blower Motor Resistor:

View attachment 29387
It shows where leaves build up in 80-96 ductwork. , If they build up around the resistors, the Bronco can catch fire if the blower motor is NOT at full speed all the time.
View attachment 29383
Blower Motor Switch Resistor Assembly
Removal
Pry the wire connector from the heater blower motor switch resistor (18591).
Remove the two screws that attach the heater blower motor switch resistor to the heater plenum chamber case (18A484).

Installation
Follow removal procedures in reverse order.
Check operation in all blower speeds
To test the blower heater blower motor switch resistor as well as the internal thermal limiter, check continuity for shorts or opens with a self-powered test lamp. If the unit indicates an open or short, it cannot be repaired and will require replacement.
●

PINPOINT TEST F: BLOWER MOTOR OPERATES IN HIGH SPEED ONLY​

F1 CHECK BLOWER OPERATION

• Key to run, function selector **** to FLOOR and blower **** at LO.

Does blower motor operate?

Yes	No
GO to F5.	GO to F2.

F2 CHECK BLOWER SWITCH HIGH SPEED​

• Slowly move blower **** from LO to HI. Stop at each detent and check for blower operation.

Does blower motor operate in any speed except HI?

Yes	No
GO to F4.	GO to F3.

F3 CHECK GROUND CIRCUIT​

• Check Circuit 57 (BK) from heater blower motor switch resistor to ground for an open.

Is ground wire open? miesk5 Note; it's a Black wire.

Yes	No
REPAIR and/or REPLACE as required.	REPLACE heater blower motor switch resistor.

F4 CHECK CIRCUIT​

• Check Circuit 261 (O/BK wire) between blower motor and heater blower motor switch resistor for open.

Is circuit open?

Yes	No
REPAIR as necessary and CHECK blower motor operation.	REPLACE heater blower motor switch resistor.

F5 CHECK BLOWER SWITCH​

• Check blower motor operation several times in each blower **** position.

Does blower motor operate in all **** positions without interruption?

Yes	No
CHECK system operation in all function positions and blower speeds. If OK, INSTRUCT owner on correct operation of system.	GO to F6.

F6 CHECK BLOWER SWITCH CONTINUITY​

• Remove harness connector from blower switch and check continuity through switch in each position.
• 
  TEST PROCEDURE
  

  Switch Position​	Continuity Between Terminals​
  Low​	B​
  Medium 1​	B + D​
  Medium 2​	B + C + D​
  High​	B + A + C​

  View attachment 29382

Is switch continuous in all positions?

Yes	No
CHECK continuity of Circuit 754 (LG/W) and Circuit 752 (Y/R) between blower switch and resistor assembly. REPAIR as required.	REPLACE heater blower motor switch.

View attachment 29384●

Lastly, the red pointer is where the rubber cowl drain boot should be under passenger side Fender, near door. I reach up in opening with my fingers to feel for debris and to remove.
View attachment 29389

View attachment 29388

WOW so great of a reply. Even I can find and fix this i think...

 

[Motech]

Yo,
Incorrect.

F3 CHECK GROUND CIRCUIT​

• Check Circuit 57 (BK) from heater blower motor switch resistor to ground for an open.

Is ground wire open?

Good post of one step in a published diagnostic chart.

Those charts can sometimes run a diagnostician in circles though. They're not always precise in their descriptions, and this one is a perfect example, where it states to "Check Circuit 57 (BK) from heater blower motor switch resistor to ground for an open"

So what are we checking there? An open circuit between blower motor switch and ground? Or an open circuit between blower motor resistor and ground? Because they are too distinctly different components, and the verbiage you quoted does not clarify which one.

Consider:



As we can see in this diagram, the blower motor speeds are ground controlled, and they all go through circuit 57 that you cited. That is the path to ground for both the switch and the resistor assembly.

For the first three speeds, the switch routes the blower ground signal through a series of different resistance levels back to that ground ckt 57. For blower motor high speed however, the switch bypasses the resistors completely and shorts the signal directly to ground ckt 57.

With that, an open circuit 57 between blower motor switch and ground would result in no high speed blower motor functions at best, and likely failure at any speed setting.

But that is not OP's symptom.

My fan only runs on high now. It that in the switch or the fan ???

It's neither.

Fact is, the only cause of good high speed fan performance with total failure in the first three speed settings is an open circuit anywhere between resistor and ground, but not between switch and ground.

Theoretically, that could be an open circuit 57 somewhere between connector C169 and splice S205.

It could also be an open circuit 261 between connector C169 and splice S152.

So what would be the next diagnostic step after the one you quoted? Do we test for an open ground circuit between the switch and ground?

No, we already have. Rether, Pamm already has.

The fact that the fan works on high confirms that that ground circuit is good. Same with fused power source, switch and blower motor.

So then we have two more circuits to test between connectors and splices (and lord knows where those splices might be), and one of those splices is not a ground, so how do we test that one?

In my experience of at least 100 high-speed-only diagnosis and repair tasks, that open circuit has always been the thermal limiter inside the resistor pack.

So I ask myself, do I want to spend a lot of time probing in circles following a diagnostic chart that clearly is unclear, often misleading?

Or better yet, I ask the paying customer:

Do you want to leave your Bronco overnight and pay me $120.00 for the time it takes to rule out every possible failed circuit scenario, then pay the cost of the actual repair on top of that?

Or would you rather benefit from my 30-plus years of experience, skip the ceremonial circuit analysis and and be done and gone in ten minutes with a new resistor?

As I would (and always do) professionally for my customers, I stand by my first reply:

If the resistor pack is plugged in, just buy a new one for 12 bucks and consider that your test and fix at the same time.

If I'm wrong I'll eat that cost, and then we'll start testing circuits.

But frankly, if it ever worked out that way, I cannot remember it now.

 

[miesk5]

Yo Motech
I went to the resistor issue immediately in my response.

The testing is by Ford.

 

[Motech]

Sure thing miesk5, same as I.

You challenged my input based upon published Ford diagnostic steps, and I replied to validate that advice by sharing my experience and by showing how those published diagnostic steps can sometimes be unclear and misleading.

Good stuff both.

 

[L\Bronco]

A faulty or disconnected blower motor resistor is the only thing that causes high speed only. Don't even bother testing. If the resistor pack is plugged in, just buy a new one for 12 bucks and consider that your test and fix at the same time.

Miesk5 was merely covering all of the possibilities. Your response stated that the resistor was the ONLY thing that could cause her failure. (Which is correct 99.9% of the time.) I think that , when helping someone with limited experience, its best to avoid absolutes, if this was one of the 0.1% scenarios, the forum loses a little credibility.
Also, Miesk5 puts in a ton of effort to help everyone who needs it (for free) maybe add a little respect in there and leave the ego at home.
Sorry, I just felt that needed to be said.

 

[Motech]

Indeed, commitment before ego.

Context often is muddied up in text form. I can see where my replies to Al might be interpreted as a little puffy, but that's not my intent. I respect his input tremendously for the outright thoroughness and the obvious time and effort spent in delivery. It is always very useful, and I'm impressed with the sheer volume of his comprehensive replies. I believe that my interactions reflect my respect pretty consistently, and I like to believe he sees that too.

I thank you for your input. If nothing else, I'm reminded to maybe soften my delivery a little bit.

My knowledge is pretty deep it matters I comment on, and I believe my hands-on, theoretical approach can often complement, or even provide a very useful alternative to the cumbersome nature of published diagnostic charts.

Thanks for the nudge.

 

[L\Bronco]

Indeed, commitment before ego.

Context often is muddied up in text form. I can see where my replies to Al might be interpreted as a little puffy, but that's not my intent. I respect his input tremendously for the outright thoroughness and the obvious time and effort spent in delivery. It is always very useful, and I'm impressed with the sheer volume of his comprehensive replies. I believe that my interactions reflect my respect pretty consistently, and I like to believe he sees that too.

I thank you for your input. If nothing else, I'm reminded to maybe soften my delivery a little bit.

My knowledge is pretty deep it matters I comment on, and I believe my hands-on, theoretical approach can often complement, or even provide a very useful alternative to the cumbersome nature of published diagnostic charts.

Thanks for the nudge.

I agree totally, I was a Tech\Foreman at a big Ford dealership from 86-99 (been wrenching since 78, licensed in 87) and Teaching at a tech institute since 99, so I definitely know where you are coming from, I, focus on getting around some of the B\S in the diag charts constantly at school.
Thanks for hearing me.

 

[trydntru]

Sounds to me like your resistor kit is unplug'd or damaged.​

1987-1997 Ford Bronco and F-Series Truck Blower Motor Resistor Kit​

1987-1997 Ford Bronco and F-Series Truck Blower Motor Resistor Kit-Broncograveyard.com

250 degree thermal limiter, for factory ACbr or NON AC trucks ot broncosbr Enggineered from high quailty materials to effectively withstand the condensation that typically causes corrosion in resistors. The durable design resists thermal fuse failure, overheating and burnout.br Restores heating...

shop.broncograveyard.com

Definitely sounds like the resistor. Same happened to my 85 now works great.

 

[Pamm]

Good post of one step in a published diagnostic chart.

Those charts can sometimes run a diagnostician in circles though. They're not always precise in their descriptions, and this one is a perfect example, where it states to "Check Circuit 57 (BK) from heater blower motor switch resistor to ground for an open"

So what are we checking there? An open circuit between blower motor switch and ground? Or an open circuit between blower motor resistor and ground? Because they are too distinctly different components, and the verbiage you quoted does not clarify which one.

Consider:

View attachment 29406

As we can see in this diagram, the blower motor speeds are ground controlled, and they all go through circuit 57 that you cited. That is the path to ground for both the switch and the resistor assembly.

For the first three speeds, the switch routes the blower ground signal through a series of different resistance levels back to that ground ckt 57. For blower motor high speed however, the switch bypasses the resistors completely and shorts the signal directly to ground ckt 57.

With that, an open circuit 57 between blower motor switch and ground would result in no high speed blower motor functions at best, and likely failure at any speed setting.

But that is not OP's symptom.



It's neither.

Fact is, the only cause of good high speed fan performance with total failure in the first three speed settings is an open circuit anywhere between resistor and ground, but not between switch and ground.

Theoretically, that could be an open circuit 57 somewhere between connector C169 and splice S205.

It could also be an open circuit 261 between connector C169 and splice S152.

So what would be the next diagnostic step after the one you quoted? Do we test for an open ground circuit between the switch and ground?

No, we already have. Rether, Pamm already has.

The fact that the fan works on high confirms that that ground circuit is good. Same with fused power source, switch and blower motor.

So then we have two more circuits to test between connectors and splices (and lord knows where those splices might be), and one of those splices is not a ground, so how do we test that one?

In my experience of at least 100 high-speed-only diagnosis and repair tasks, that open circuit has always been the thermal limiter inside the resistor pack.

So I ask myself, do I want to spend a lot of time probing in circles following a diagnostic chart that clearly is unclear, often misleading?

Or better yet, I ask the paying customer:

Do you want to leave your Bronco overnight and pay me $120.00 for the time it takes to rule out every possible failed circuit scenario, then pay the cost of the actual repair on top of that?

Or would you rather benefit from my 30-plus years of experience, skip the ceremonial circuit analysis and and be done and gone in ten minutes with a new resistor?

As I would (and always do) professionally for my customers, I stand by my first reply:



If I'm wrong I'll eat that cost, and then we'll start testing circuits.

But frankly, if it ever worked out that way, I cannot remember it now.

Wow, well i seen that my board and plus are so rusted that both needs replacing, pics will be attached. Had a rough time getting the board off and tore the plug up trying to unplug

 

[Pamm]

Pics on badly rusted board and plug. Part # on old one is E7TH-19A706AA . The only match I seen at rock auto was cheap one $7.81 I hope they have a better one. I need a harness too. I'll wait and look for a response on here before I order it.

 

[Tiha]

On rock auto the DORMAN 973412 comes with the plug.

 

[Pamm]

On rock auto the DORMAN 973412 comes with the plug.

This doesn't match my part number EZTH-19A706AA ( 1995 ) bronco......... Will it work?

 

[Motech]

Pics on badly rusted board and plug. Part # on old one is E7TH-19A706AA . The only match I seen at rock auto was cheap one $7.81 I hope they have a better one. I need a harness too. I'll wait and look for a response on here before I order it.

That kind of moisture would have me looking at heater core too.

On rock auto the DORMAN 973412 comes with the plug.

Great find!

I checked my local sources for grins; none on shelf, but in next-day warehouses, and none of the other common brands include a connector.

 

[Motech]

This doesn't match my part number EZTH-19A706AA ( 1995 ) bronco......... Will it work?

Obsolete from Ford, and it probably changed part numbers a few times over then years.

Looks like a match by above pics though.

 

[Tiha]

This doesn't match my part number EZTH-19A706AA ( 1995 ) bronco......... Will it work?

Sorry I should have posted more.

Yes,
DORMAN 973412 {#4C2Z19A706BA, E7TZ19A706A, 973-412} Kit

It is pretty generic. We have been doing this crap a long time. If it looks even close it will work. LOL