Voltage loss to blower motor (1969 with factory A/C)

[MaximRecoil]

I need to troubleshoot my blower motor. The problem is, though it has 3 distinct speeds (which means the resistor is working), they are all very slow. When it is on high, it is more like what I would expect low to be, and you can barely even hear/feel it on medium and low. This isn't a recent problem; it has always been like that ever since the first time I tried the heater in this car.

I connected the blower motor directly to the battery, and it worked good, at least twice the speed of its high setting when it's hooked up normally, and that's only with 12.6 volts (because the engine was off). So there has to be high resistance somewhere in its circuit, even on high when it should be bypassing the resistor.

The voltage at the fuse is good: with the engine running it is a little over 14 volts, and with the engine running and the blower motor on high it is a little under 14 volts.

So I'd like to check the connections at the resistor, but I don't know where it is, and I'd like to have an idea of where to look for it rather than just blindly tearing stuff apart hoping to come across it.

[A383Wing]

same place as a non-ac car...mounted in the front panel of heater box under dash....ye gonna have to take some ducting out to get to it

[MaximRecoil]

I don't know where it is on a non-A/C car either, but I know the heater boxes are different between an A/C and non-A/C car, so I mentioned it was an A/C car.

Is it located more toward the far right side of the car or more toward the transmission hump?

[Back N Black]

Here you go....

[elacruze]

The problem spots to look for are the firewall connector hot line and blower wire, and the keyswitch plug. Verify that they are not heat-damaged and use a vinegar/salt solution to clean the connectors (rinse with water, dry with hair dryer and reassemble with dielectric grease) The resistor terminals could be involved but seems unlikely since the problem is across all the commonly powered circuits.

[MaximRecoil]

Here you go....

Thanks for the picture.

The problem spots to look for are the firewall connector hot line and blower wire, and the keyswitch plug. Verify that they are not heat-damaged and use a vinegar/salt solution to clean the connectors (rinse with water, dry with hair dryer and reassemble with dielectric grease) The resistor terminals could be involved but seems unlikely since the problem is across all the commonly powered circuits.

The problem is quite the mystery to me right now, because while the relevant terminals may not be 100% sparkling clean, I can't imagine them introducing enough resistance to reduce the blower motor speed by at least half. As I mentioned in the OP, the voltage at the blower motor fuse is good (good at all the fuses for that matter), which comes after the bulkhead connector, so the voltage there is good by default too. That much resistance has to be generating heat somewhere, but I haven't found it.

[MaximRecoil]

Today I measured the voltage at the blower motor with the "heat" button pushed in and the fan switch on high (pushed all the way forward), and it is about 6 volts. Then something strange happened: I pushed the A/C button, and the blower motor increased in speed. I measured it and it was at about 9 volts, same deal with the Max A/C button.

What the hell?

When the fan switch is on high, shouldn't it be bypassing the resistor, and shouldn't "high" be "high" regardless of whether "heat" or "A/C" / "Max A/C" is selected? Where is the extra 3 volts coming from when I push the A/C or Max A/C button instead of the heat button, and why is it still a few volts lower than it should be? 

I still haven't found the resistor, but I haven't started removing duct work either (I don't look forward to doing that).

[ws23rt]

Today I measured the voltage at the blower motor with the "heat" button pushed in and the fan switch on high (pushed all the way forward), and it is about 6 volts. Then something strange happened: I pushed the A/C button, and the blower motor increased in speed. I measured it and it was at about 9 volts, same deal with the Max A/C button.

What the hell?

When the fan switch is on high, shouldn't it be bypassing the resistor, and shouldn't "high" be "high" regardless of whether "heat" or "A/C" / "Max A/C" is selected? Where is the extra 3 volts coming from when I push the A/C or Max A/C button instead of the heat button, and why is it still a few volts lower than it should be? 

I still haven't found the resistor, but I haven't started removing duct work either (I don't look forward to doing that).

Life is much better for us when you argue with yourself. 
Pretend that you are talking to a person and pick their answers to pieces. It is the same as eliminating possible causes for your problem on your own.
You can find the trouble and let us know what it was.   Much better

[A383Wing]

I don't care who ya are, that was funny right there.... 

[MaximRecoil]

Today I measured the voltage at the blower motor with the "heat" button pushed in and the fan switch on high (pushed all the way forward), and it is about 6 volts. Then something strange happened: I pushed the A/C button, and the blower motor increased in speed. I measured it and it was at about 9 volts, same deal with the Max A/C button.

What the hell?

When the fan switch is on high, shouldn't it be bypassing the resistor, and shouldn't "high" be "high" regardless of whether "heat" or "A/C" / "Max A/C" is selected? Where is the extra 3 volts coming from when I push the A/C or Max A/C button instead of the heat button, and why is it still a few volts lower than it should be? 

I still haven't found the resistor, but I haven't started removing duct work either (I don't look forward to doing that).

Life is much better for us when you argue with yourself. 
Pretend that you are talking to a person and pick their answers to pieces. It is the same as eliminating possible causes for your problem on your own.
You can find the trouble and let us know what it was.   Much better

Go hijack a different thread with your out-of-left-field inanities, simpleton.

[ws23rt]

Today I measured the voltage at the blower motor with the "heat" button pushed in and the fan switch on high (pushed all the way forward), and it is about 6 volts. Then something strange happened: I pushed the A/C button, and the blower motor increased in speed. I measured it and it was at about 9 volts, same deal with the Max A/C button.

What the hell?

When the fan switch is on high, shouldn't it be bypassing the resistor, and shouldn't "high" be "high" regardless of whether "heat" or "A/C" / "Max A/C" is selected? Where is the extra 3 volts coming from when I push the A/C or Max A/C button instead of the heat button, and why is it still a few volts lower than it should be?  

I still haven't found the resistor, but I haven't started removing duct work either (I don't look forward to doing that).

Life is much better for us when you argue with yourself.  
Pretend that you are talking to a person and pick their answers to pieces. It is the same as eliminating possible causes for your problem on your own.
You can find the trouble and let us know what it was.   Much better

Go hijack a different thread with your out-of-left-field inanities, simpleton.

No hijack-- I was answering to the topic and suggested a quick easy way to your needed solution.

We are here to help everyone and that is my motive.

BTW I am a simpleton in that I like things to get to the point. I say what I feel and the fewer words the better.  Communication is the bottom line however that happens.

A game of words leads off topic.

[MaximRecoil]

Again, since you don't read so well:

Go hijack a different thread with your out-of-left-field inanities, simpleton.

[ws23rt]

Again, since you don't read so well:

Go hijack a different thread with your out-of-left-field inanities, simpleton.

Is this a sttammer?

[MaximRecoil]

Again, since you don't read so well:

Go hijack a different thread with your out-of-left-field inanities, simpleton.

[ws23rt]

Just responding to a reply within a topic

[A383Wing]

Again, since you don't read so well:

Go hijack a different thread with your out-of-left-field inanities, simpleton.

Is this a sttammer?

his recording is stuck on repeat

[MaximRecoil]

Just responding to a reply within a topic

Again, since you don't read so well:

Go hijack a different thread with your out-of-left-field inanities, simpleton.

his recording is stuck on repeat

You should also go hijack a different thread, Ankle Biter #2.

[ws23rt]

Just responding to a reply within a topic

Again, since you don't read so well:

Go hijack a different thread with your out-of-left-field inanities, simpleton.

his recording is stuck on repeat

You should also go hijack a different thread, Ankle Biter #2.

When an ankle biter strikes and you feel the venom.  Where do you think that venom comes from?---
We are not naturally poisonous.  It is human nature to self defend.  You attack---we defend.  It will stop when the attack stops or we die.

Can this be a hijack?--- A response to the OP?

[ws23rt]

Today I measured the voltage at the blower motor with the "heat" button pushed in and the fan switch on high (pushed all the way forward), and it is about 6 volts. Then something strange happened: I pushed the A/C button, and the blower motor increased in speed. I measured it and it was at about 9 volts, same deal with the Max A/C button.

What the hell?

When the fan switch is on high, shouldn't it be bypassing the resistor, and shouldn't "high" be "high" regardless of whether "heat" or "A/C" / "Max A/C" is selected? Where is the extra 3 volts coming from when I push the A/C or Max A/C button instead of the heat button, and why is it still a few volts lower than it should be? 

I still haven't found the resistor, but I haven't started removing duct work either (I don't look forward to doing that).

Life is much better for us when you argue with yourself. 
Pretend that you are talking to a person and pick their answers to pieces. It is the same as eliminating possible causes for your problem on your own.
You can find the trouble and let us know what it was.   Much better

Go hijack a different thread with your out-of-left-field inanities, simpleton.

My understanding of what it means to hijack is to go off topic and start a different conversation.

I did not go off topic. I was on topic with my best advice to you to help you find the answer to your topic question.

You however asked--(told) me to go hijack a different thread--??? 

It seems to me as though you hijacked your own thread by changing the topic provoking a response to something that is off topic.

Don't you realize how rude it is to hijack??

Since you are the originator of the thread it may be just fine

Do you think this thread should be locked due to contamination??

[MaximRecoil]

When an ankle biter strikes and you feel the venom.  Where do you think that venom comes from?---
We are not naturally poisonous.  It is human nature to self defend.  You attack---we defend.  It will stop when the attack stops or we die.

"Venom"? What venom? Ankle biters have no venom:



And no, I don't "attack", and you won't find a single example of me doing so on this forum.

Can this be a hijack?--- A response to the OP?

Did your post point out the location of the blower motor resistor on a '69 with factory air conditioning, or did it contain possible causes of the low voltage to the blower motor? No, it didn't, and nothing else is relevant to my OP. Your post was nothing more than an irrelevant attempt at being a smartass, thus a thread hijack.

Ask yourself: would you have made the same post if the OP was my very first post on this forum? Obviously not. Your post was motivated by some pathetic little obsession you have with me personally (the same thing motivates all internet ankle biters), carried over from other threads. Replying to the poster rather than to the content of the post is always a hijack in threads of this type.

My understanding of what it means to hijack is to go off topic and start a different conversation.

I did not go off topic. I was on topic with my best advice to you to help you find the answer to your topic question.

You however asked--(told) me to go hijack a different thread--??? 

It seems to me as though you hijacked your own thread by changing the topic provoking a response to something that is off topic.

Don't you realize how rude it is to hijack??

Since you are the originator of the thread it may be just fine

Do you think this thread should be locked due to contamination??

See above, simple fellow.

[Cooter]

Fyi....these blower motors do not ever blow like newer cars. Chasing your tail on this one. If running Chrysler alt. Will run even slower when at idle.

[bill440rt]

The one in my '70 has the same characteristics as you describe. Not a powerful blow, but the A/C is still freezing.

Sorry to hijack.

[MaximRecoil]

Fyi....these blower motors do not ever blow like newer cars. Chasing your tail on this one. If running Chrysler alt. Will run even slower when at idle.

There still has to be a reason for it only being ~6 volts at the blower motor; that's a loss of over 8 volts compared to alternator voltage. Then the blower motor speed increases simply by selecting A/C or Max A/C, without touching the fan speed switch (measures ~9 volts at the blower then). But no setting on the controls gets it to the speed it is capable of when you connect it directly to the battery.

It must be going through one of the resistors in the blower motor resistor unit even when on high, and then going through a less resistive resistor in the same unit when A/C is selected. But that makes no sense; it should be bypassing the resistor completely on high; that's how it works in every vehicle I know of, and I believe the schematics in the FSM shows a resistor bypass circuit for "high" (I'd have to double-check that though).

The one in my '70 has the same characteristics as you describe. Not a powerful blow, but the A/C is still freezing.

Does your fan increase in speed simply by selecting A/C or Max A/C, without touching the fan speed switch? With the engine running, what is the voltage at your blower motor when "heat" and "high" are selected? What is the voltage at your blower motor when "A/C" or "Max A/C" and "high" are selected?

Sorry to hijack.

Say what?

[MaximRecoil]

it should be bypassing the resistor completely on high; that's how it works in every vehicle I know of, and I believe the schematics in the FSM shows a resistor bypass circuit for "high" (I'd have to double-check that though).

Okay, here it is:



On high, the blower motor resistor is bypassed; nothing but ordinary wires and terminals between the switch and the motor. So where am I losing ~8 volts on heat/high, and where am I regaining ~3 of those lost ~8 volts on AC/high?

[John_Kunkel]

I, too, was concerned about what I perceived as low blower speed (especially in HIGH) so I connected the motor directly to the battery and the speed rose to what I considered "correct"....problem is the motor got so hot it blistered the paint.

Draw your own conclusions.