Blower motor draws lots of current???

Knebel

Knebel

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So I have this thing happening that when I turn my blower motor on high, my charging voltage drops dramatically.

I'm wondering if it is easy to rebuild the motor and if there are parts available. Its not that big of a deal normally but now with my electric fan and AC it is very noticeable. I already have a 95amp alternator that puts out almost 90amps at idle according to the spec sheet! I have an adjustable voltage regulator, would it help to adjust the charging voltage up a little bit?

Here is a little video on how my voltage behaves:
 
The high current flow that your blower motor is drawing needs to be addressed soon or you will have melted connections, switches and wires. Possibly a fire. I would not run the motor on high at all until you either replace it or have it serviced. After all these years, they get dry dirty and tired causing what you are experiencing. I worry about people that upgrade to (like you) a 90A alternator without upgrading the wiring. To me it is asking for a meltdown or fire. You need to add some relays for the headlights also to stop a lot of that current flow from from flowing through the bulkhead connectors. I also don't think you should adjust the voltage any higher since it seems to be where it should be. Much over 14 volts will cook your battery.
 
Simply said, that seems to be exactly how the blower motors fail. They start drawing higher current until they either fail or some other component, like a switch, fails.

Replacements are pretty generic and easy to find. Don't screw with it much and be thankful you don't own a Formal.
 
It's "amps" that run things, not specifically "volts". Which gets back to your alternator output at idle. Get the system on a Sunn (or similar) charging system checker to see what the alternator IS actually putting out on the vehicle. Make sure that all of the battery cable ends and posts are clean, too (dirty cable ends/terminals can drop alternator output by 10%, as we found out in our shop at work, one night). Is the regulator and electronic version? Wondering why it might not be picking up the additional load?

Modern cars with 150+amp alternators have wiring that seems a bit smaller than what Chrysler used back then, by observation. Just that they use the computers to turn the circuits on and off, kind of like a relay of sorts. BTAIM

As for the motor, the bushings have probably gotten a bit dry over the years, I suspect. That's probably where your power drain is coming from. Until you get a new motor, try not to run the system on "High", when "medium" will probably work almost as well.

Just some thoughts,
CBODY67
 
Whenever I get a new addition to my fleet, the first thing I do is replace the original blower motor with something current. Identical modern ones are available from companies like Bosch that will go the distance. Almost all the C bodies I have come to me with melted wires that source the blower motor. Just fix the piece of cheap junk and avoid a lot of trouble.
 
Ok I did leave a lot of things out. I have all my big charging and starter and ground wires upgraded to...i think it was 1 gauge. I didnt just throw a 90amp alternator on a old brittle witing. The ampmeter is also bypassed. I have Leds all around they draw practically nothing.
So I will be pulling that motor and see whats going on! Good to know to have the input from you guys! Thank you!
 
Change out the blower motor and while yer at it get a new resisitor for it too.
I agree that it is not volts it is amps that should be checked on the output of alternator.
Also it is normal to see voltage drop at idle with full load.
You should increase the RPM under full electrical load to ensure the alternator and voltage regulator puts out.
Regulator will spike to 14 volts under full load and should drop when battery has got a full charge.

I swapped out my alternator despite reading good voltage but was only putting out 5 out of 38 amps.
Hope this helps.
 
saforwardlook said:
Whenever I get a new addition to my fleet, the first thing I do is replace the original blower motor with something current. Identical modern ones are available from companies like Bosch that will go the distance. Almost all the C bodies I have come to me with melted wires that source the blower motor. Just fix the piece of cheap junk and avoid a lot of trouble.
Click to expand...

Could you, or anyone else of course, provide an example of a suitable replacement blower motor (for a 69 c-body in my particular case)?

Thanks.
 
Last edited:
Little updade. Pulled the motor and its a reman made in mexico. The spherical front bushing was extremely tight, almost seized on the rotorshaft.

I took it all apart, cleaned it up, polished it out and it now spins way more smoothly and free. Voltage drop on high is about 0.2V, the ground connecrion is not that great so ill attend to that next. Still, with my electric fan, it barely keeps it at 12v to 12.2v now...better than 11.5v for sure...
 
Knebel said:
Little updade. Pulled the motor and its a reman made in mexico. The spherical front bushing was extremely tight, almost seized on the rotorshaft.

I took it all apart, cleaned it up, polished it out and it now spins way more smoothly and free. Voltage drop on high is about 0.2V, the ground connecrion is not that great so ill attend to that next. Still, with my electric fan, it barely keeps it at 12v to 12.2v now...better than 11.5v for sure...
Click to expand...
But that is at idle ,right? How often and how long do you idle your car?
But when driving it should be fine as the engine RPM"S are higher.
Keep in mind,as you may already know, when you turn on the A/C the compressor and related electrical items turn on as well.
Glad to hear you addressed the blower motor. I still recommend checking the ampperage output of the alternator
Maybe integrating a relays for the switch,the compressor's clutch,, and another for the motor to take the brunt of the load??
 
Yeah you're correct. Where I live... I idle a lot lol. The thing is that my electric fan wont have the full output if my voltage gets dragged down so much, that in return affects my cooling... so anything I can do to minimize the voltage drop at Idle I'll try!

I guess I could get a relay circuit done for the ac compressor...
 
NY69 said:
Could you, or anyone else of course, provide an example of a suitable replacement blower motor (for a 69 c-body in my particular case)?

Thanks.
Click to expand...

The last one I bought came from O'Reillys:

https://www.oreillyauto.com/detail/...1969-chrysler-new-yorker?q=blower+motor&pos=0

It even has the correct hole in the case for the hose.

You have to reuse your old blower cage.

The worst part of the job is removing the inner fender on the passenger side to access it.

Not much money...............
 
Maybe there are no O'Reilly's stores in New Foundland - but the link should still work?????
 
Oh, got it now, sorry about that, from here (EU) it is only accessible with a vpn connection via the USA. One of the many, many blessings of EU regulation. :rolleyes:
Thanks a lot!
 
NY69 said:
Oh, got it now, sorry about that, from here (EU) it is only accessible with a vpn connection via the USA. One of the many, many blessings of EU regulation. :rolleyes:
Thanks a lot!
Click to expand...

So are you in the Netherlands then?

Glad you got the link to work.
 
VDO/Continental seems to have the same part number (PM202) as the Murray unit, and they look awfully alike to me. Even the photos seem to be the same.

(VDO is available at Rockauto, for all EU customers out there.)
 
330dTA said:
VDO/Continental seems to have the same part number (PM202) as the Murray unit, and they look awfully alike to me. Even the photos seem to be the same.

(VDO is available at Rockauto, for all EU customers out there.)
Click to expand...
It's been my contention for a long time that a big majority of parts that are sold in the aftermarket come from the same source. Murray might repackage a VDO unit or the other way around... Buy the same one in a Four Seasons box etc. Some electric motor factory builds them to sell to the aftermarket and they box them accordingly. Often even the part numbers are the same or maybe have a different prefix.

For example, I've bought NORS wheel cylinders with different names on the boxes (Raybestos, Wagner etc.) and saw the exact same casting numbers on each one. All were obviously made in the same factory. They match the NOS Mopar cylinders too...
 
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