just starting to fix up my new '72 Cutlass Supreme, my blower is working. The fuse is good. is there anything else I should check
before I pull the inner fender to get to the motor?

 

Air conditioning or heater only?

If it doesn't work on any speed first check the motor ground. Then find the purple wire to the motor and make sure it has power with ignition switch in "run".

If it has power, bad motor or dirty connections. If not, time to consult the shop manual wiring diagrams.

 

Thanks!

 

If you pull the liner back you can jumper the motor to the battery + where the purple connects to test the motor. This will run the motor only on hi speed.

Definitely check the motor ground. If this is an AC car you should be able to jumper the motor at the high speed blower relay without pulling the liner.

Good luck!!!

 

Great, it's an AC car.thanks for the help

 

If the motor doesn’t run in any position, most likely the relay or motor is defective. Check the motor ground first. The high blower speed and the lower speeds are technically separate circuits with separate power sources and fuses, isolated by the relay.

The relay connector is known to melt. This is usually caused by a blower motor pulling an excessive amount of current.

 

It's working now. I pulled back the inner fender and felt around for the wires. I turned the key and the blower came on. Must have been a loose connection and I jiggled the wire enough to get it to work.
I jiggled the wire and connections and its staying on (For now) .
Of course there's no air coming into the cabin, I'll check the ductwork. Is it possible leaves or rat's nest is blocking the flow somewhere?

 

Get in there and clean/tighten the connections before they burn.

 

Definitely will.

Update on cabin air:

big wad of insulation partially blocking airflow



ductwork missing that attaches to driver side of this



ducts falling apart, not connected.


all the connections are sloppy, nothing seems like its bolted into place. Hopefully I can find the pieces I need shouldn't be too hard to fix.
Thanks for all the helpful advice!

 

Looks like you found a mouse house, been chasing those myself and the count is at 5

One of my next projects in getting into this too as my blower motor doesn't seem to work either...

 

Ugh, I pulled the back seat and it was disgusting. The car sat in a carport for twenty years and was home to GENERATIONS of mice.

Anyways, about the blower.
After I got everything back together it stopped working. Almost 2 weeks later I turned the key and it's working fine.
What's up with that?

 

It is common for amperage draw to increase as the armature shaft bushings wore. Not enough to cause the blower motor to stop running by itself or a fuse to blow but enough to cause the circuit (wires and connectors) to get hot and distort. You found the bad connection when you jiggled the wires but you really didn't fix anything. The connector is probably melted and requires replacement. But that doesn't fix the root cause of the problem - high current draw. You could get scientific and use an amp meter with a current scale of at least 30 amps to measure the current draw or take a really good stab at it and replace the blower motor.
Something else to think about is the rodent nest you found in the blower case. This could have prevented the blower from turning freely. That too would could high current draw.
If the vehicle was in my service bay I would inspect and repair the blower circuit wiring and connectors and replace the 50 year old blower motor because repeatedly pulling the fender off gets to be tiring.

Three paragraphs and I didn't mention delta once!

 

Thanks! I guess replacing the blower is not a bad idea.
My alternator is putting out 16 volts, could that cause it?

 

With a high charging system voltage the battery will cook, the alternator may have a short life and yes electrical accessories may be damaged. How long has the charging system ran at 16V ?

 

I just got the car, only put about 30 miles on it and haven't run it since I checked the voltage. Who knows how long the PO drove it like that.
What would cause the high voltage?

 

Could be anything, but first do this.
With all accessories off in the car, IGN off, doors closed - what is the exact voltage of the battery?
Hate to be picky, what is the exact voltage at the battery with the engine at idle and ALL accessories in the OFF position & doors closed?

 

Don’t replace the motor yet. What if you find the blower is not TURNING but continues to draw more and more amperage to overcome a blower whose blades are not turning only to find the entire blower blades assembly is packed with rat/mouse insulation etc. and only needs to be removed and cleaned?

Imagine you turning on a room fan to high and holding the blades.

 

Th PO may not have run it like that - don’t make assumptions. Anyone could have hooked up wires just before you bought it. You should have the wiring diagram in the Chassis Service Manual and if you don’t have a CSM - buy an original used paper edition - plenty on eBay and the like.

Since you apparently have a serious electrical issue (evidently with the blower/motor circuit, without getting over technical here yet, you should isolate and remove that circuit causing the high amperage/voltage draw for now. With the car in idle remove the fuse(s) one by one watching the voltage at the battery until the voltage drops below 15V most likely between 14V to 14.4V. Leave that fuse out of the fuse box for now. That will remove the faulty circuit so you aren’t burning something up and you can then move forward further diagnosing.

 

Crap, I left my meter at work. I'll see if I can find one tomorrow.

 

The cause of overcharging is almost always the voltage regulator.
Has any modifications to the charging system been done?
What alternator is currently on the vehicle?
What type of voltage regulator (internal or external) is on the vehicle?
Has any part of the charging system wiring harness been modified or damaged?
How do you know the charging system voltage is 16v? Are you using an accurate volt meter?
High charging system output is not going to caused by any defective electrical accessory like your blower motor. I suggest you connect an accurate voltmeter to the battery terminals. If in fact the reading is over 14.9 volts, and everything above is ok disconnect the voltage regulator (Internal regulator-two wire connector on the rear/side of the alternator or external regulator four wire connector on the firewall) while watching the volt meter. It should drop down to battery voltage. This may indicate a bad voltage regulator.
Please post your findings or additional questions. If you like you can PM me for phone help or a FaceTime walk through.

 

Sorry Norm I didn't see your second and third post last night.
You and Dynoking have given me some great advice and I'll be looking into these tonight or tommorow,
I'll keep you posted.
Thanks for the offer Dynoking, I may have to take you up on that.

 

Be careful with rodent ****. Hantavirus is not good.

 

Pub - Purchase & own (if you have not done so already) the 1972 Original Oldsmobile Chassis Service Manual - it will be your most valuable resource for your vehicle - it is the bible, includes color wiring diagram procedures for removal/installation for your vehicle. Purchase the paper copy (used) original. Digital copies and newer "copies" most often lack pages, diagrams are poor, etc. It's the best investment you can make. You might search other locations for less expensive. The key is to get it into your hands ASAP. Don't assume the 1971 Wiring Diagram is exactly the same as your 1972 - for the most part they most likely are the same except for location(s) of select items e.g. your VR is located on the firewall while the 1971 VR is located on the fender area; yet, that specific information is contained in the CSM. Here's a link to the 1971 Wiring Diagram.

1972 Oldsmobile Chassis Service Manual

 

update!
Battery running 12.6 off, 15.95 at idle.
Pulling the blower fuse- no change
Unplugged the VR, battery dropped to 12.6.
Looks like the VR is bad, hopefully that's what's affecting the blower motor

 

Ok, before we change parts. Has the alternator been "upgraded"? Is the voltage regulator internal (inside the alternator) or external (on the firewall)?
Sorry high charging system output will not cause your blower motor to run intermittently when you wiggle the blower motor harness. Re-read my post # 12.

 

Alternator looks stock, VR is mounted on the firewall.
I don't know if giggling the wires made the blower start working now, since it stopped working and started working without me touching anything.
I can check the wires and connectors for signs of overheating and pull the blower to check for more blockages.

 

Replace the VR and retest charging system voltage.
Continue with inspection of the blower circuit wiring. If you are going to go through the trouble of removing the blower motor to check for rodent nests I would replace the 50 YO blower based on MAW. I think the fender has to be removed no? I wouldn't want to do that twice.
The next issue is finding quality replacement parts. Personally I use AC Delco for my GM cars. Maybe others can chime in with suggestions based on actual experience...

 

Pug - It would be very helpful if you could validate the Part Number on your Alternator. I realize it might be difficult depending on the alternator currently installed in the vehicle, since sometimes (depending), the Part Number may be on the underside. Do your best to see if you can see the part number. If you can't validate the alternator part number, don't remove it to find it, it would assist a great deal if you can take a picture of (1) your alternator & (2) your VR (which is correct, your VR is located on the firewall for a 1972). There are a couple things we (in particular, Dyno) can learn from the Alternator: (1) is it the original or an aftermarket OEM alternator (2) does it have one wire or two wires (there are a couple upgrades to alternators with various plug types over the years); and, (3) you may find this hard to believe (LOL), but sometimes a PO in good faith will wire the Alternator incorrectly, use the incorrect plug and sometimes hook up the VR incorrectly (especially based upon the alternator type and plug employed). Pictures would assist.

 

pics



Didn't see a number, I can take it off if needed. BTW, I have a chassis service manual on the way.
I was set to order a Delco Remy VR, there a lot of bad reviews.

 

My impression of online reviews is most folks with nothing bad to say don't post reviews, so what you see is mostly the people who had bad experiences. So even if there's only 1% bad parts, the online reviews make it see as if the percentage is a lot higher.

 

Pug - Thanks for the pics. I am no guru on alternators, there are many more members with far greater knowledge of alternators than me. Without going into what I do know and I don't know, it "appears" to me the alternator on your car is a 10SI alternator, which I believe is an internal voltage regulator alternator. I own a 1971 CS and my OEM alternator is of the 10DN series designation Delco Remy alternators. Those numbers e.g. 10DN, 10SI, 12SI, CS130, etc. are not part numbers but instead series designations. To the best of my limited understanding, all 10DN series Delco Remy alternators use an external VR; while both the 10SI & the 12SI Delco Remy alternators have an internal VR. With that said, I am not the person to assist much further because I have not converted a 10SI (internal VR) alternator capable of using an external VR. So, I'm pretty much dead in the water on assistance. There are others who can assist you further. You can convert a 10SI to use an external VR but I don't have the breadth of knowledge to assist you any further in determining if the wiring is correct - I do know by simply learning from others the conversion is possible but it requires the correct plug and modest rearrangement of wires. So, I'll allow others with more knowledge to assist you and inform me if I'm correct/incorrect regarding my assessment. I believe your 1972 used an external VR with a 10DN alternator as OEM, but again, I'm not the correct person.

 

Well, Pug - I think I have some things correct, other(s) not so much, but apparently the 1972 model year was "unique":

And, I have no idea what a "different" plug suggests because I don't have the knowledge. But, a quick search of 10SI demonstrates some unique threads/posts/discussions. I'll let others w/ more knowledge assist you further. It may in fact be wired correctly, just beyond my abilities.

Search for 10SI

https://classicoldsmobile.com/forums...archid=6223652

 

Norm, he already confirmed it has an external voltage regulator.

​​​​​​​

 

Ken, yeah I know. But I wasn't certain if the alternator was the correct type alternator for an external VR & whether a picture would assist in helping to determine if the ALT was wired correctly to the VR - the pics helped. I didn't know the 1972 model year used a 10SI case with an external VR and a different plug - unique to 1972 model year applications evidently.

 

I can see where having 2 VRs would be a problem, I'm thinking I just have the one bad one.
Thanks for going to so much trouble Norm.
It will be next weekend at least before I'll go digging around in the blower motor, I'll let you know if I find anything

 

I wasn't concerned about having two VRs. I was concerned if the alternator was correct for your model year and whether the wiring might be suspect since you can convert the 10SI (normally internal VR) to use external VR. Turns out the 1972 model year employs the 10SI case with a different plug - I learned something here for sure. Good luck.

 

The alternator in the photo appears to be stock. The square field connector indicates it is an external regulator. Please carefully inspect the charging system wiring harness. I would feel much better if you could perform a voltage drop test of the charging system power and ground circuits. (google is your friend) Lacking that a reasonable guess would be to replace the VR.

 

Agreed. I would not rely on backyard parts changers reviews of electrical parts in my purchase decisions.

 

Now I'm wondering if the VR is bad or just needs to be grounded

 

No matter what that ground step has to be repaired. The firewall VR gets grounded through its case to the firewall. You should check for corrosion by unbolting it then inspect and clean the case under the mounting bolts and the corresponding threaded holes on the firewall. After you clean the mounting points use dielectric grease to coat the area(s) that you scraped clean to prevent corrosion from recurring. Then retest the charging system output.