Jump to content

AC resistor part# needed for 76 Electra with auto temp control (C61)


Recommended Posts

I am trying to find the part number for the AC blower resistor for my 76 Electra Park Avenue with fully automatic climate control, GM production code C61. None of the parts cataloges has entry for a resistor for this option. All I could find for a 76 C model is a part number for option C60 which is the manual AC control. The part number listed for this option is 500890 but this resistor has 4 prongs and is very common. The resistor I have has only 2 prongs. I perused parts catalogs for other GM models covering 1976 model year and they also only list a resistor for option C60. If anyone could point me the right direction with my research would be much appreciated!

Link to comment
Share on other sites

Thank you for your reply! No, it's not the ambient switch, it's the resistor pictured on the second page you scanned. It also pictures a 4-prong resistor which is used for manual or semi-automatic climate control. Here is a picture of the resistor on my car.20220505_121951.jpg.6890785065a64158c6ca6a52e080e2c6.jpg

Link to comment
Share on other sites

Never seen a resistor like that. What does it look like on the underside?

 

Do you have 1976 Buick factory chassis manual? Bound to think it would be covered there. Does anyone know if Buick published an ATC supplement manual that may have covered a running change?

 

Good luck.

Link to comment
Share on other sites

This weekend I'll remove it and check out what's on the underside, I'll post a picture. I do have the chassis manual but as you can see on the electrical diagram it does show a 2-prong resistor (ambient sensor). Same goes for the parts illustration manual. My parts catalog is from 1987 covering 1976 to 1981 and you would think by that time this part would be listed but that's not the case. The same type of automatic climate control was already available at least in the 1974 model year if so this is not unique to 1976. The closest configuration I came across is a combination of ambient temp switch and resistor that was used on early 70s Cadillacs and Pontiacs. It does have only 2 prongs but also have a button type sensor.0.jpeg.97ae450b03ff4d50341fb0da41c07224.jpeg1971-76-Chevrolet-automatic-air-conditioning-sensor-7930125-1.jpg.d24bf926cc3d63aadded1f58f0ac6a54.jpg1971-76-Chevrolet-automatic-air-conditioning-sensor-7930125.jpg.e61168133d27ce69135d3c0b0e07131b.jpg

Link to comment
Share on other sites

What is the operational issue you are chasing?

 

On the later systems, in the 1990s, with the full ATC on Buicks, there was NOT a "blower motor resistor" but a "blower control MODULE",  key difference.  On the underside of the mounting plate, was a circuit board with a big heat sink attached to it.  If the blower motor did not work correctly, THAT was the part that got replaced.  No separate wound wire resistors as the non-C61 system had.  I would suspect that what you've pictured is the ambient air sensor rather than the desired blower control module.

 

Perhaps, you might need to find a publication or video (on YouTube) of the technician's training on the C61 system from back then, IF they might be available.  Regarding GM parts books, you need the one with the printing date CLOSEST to the date of the vehicle's manufacture, not one from years later.  Reason?  With the later printings, I've observed that parts which they suspected would be "sold out" or existing parts stock (and not replaced or superceded) by the time the book was printed . . . those part numbers will NOT be listed in the later versions/printings.  I discovered this dealing with the later printings of Chevrolet parts books regarding the later versions and the much-earlier printings regarding 1955-57 Chevy parts.  The numbers I was looking for were not in the later printings, but the original listings were still available from GM parts.  I was ordering and getting '55-'57 rocker panel moldings and license plate light assys well into the 1980s, but those numbers had been deleted from the later printings of the "earlier model" parts books.  BUT, as demand for those parts was still happening, GM kept building them.  The moldings came in the later-style wrappers, too.  The license plate lights were not "GUIDE", but from another vendor, but were OEM correct other than the name on the lens.

 

Perhaps, there might be some help in the Cadillac area of things?  Perhaps something in the correct GM Body Service Manual?

 

Just some thoughts and observations,

NTX5467  

  • Like 1
Link to comment
Share on other sites

Posted (edited)

There is no issue with the sensor or the blower but I am always looking to refresh components on the car as well as look for spare parts. It helps me to thoroughly know the car and familiarize myself with automotive technology of the era.

 

You did point me in the right direction and I'm pretty sure I solved the mystery. I kept searching and looking for a resistor when I should have searched for a sensor. With that said I did check before I posted here the entries in the applicable Buick parts catalog for ambient air sensor, however, none was listed for a 76 C. By the way, I get your point about the date of the parts catalog, I discovered myself some numbers missing. However, I also have a 1976 to 1978 catalog issued in April 1978 and even that issue is lacking an entry for SENSOR, Ambient air for a 76 C model. Hence I hit a dead end with the sensor issue.

 

Then based on your suggestion I searched this time the internet for ambient air sensor and that led me to entries in the Buick parts catalog covering models through 1975 and the 1976 to 1978 Cadillac parts catalog. Still not sure why they made no entries in the Buick catalog specifically for a 76 C when there was one in the Cadillac catalog. The Buick listing I found is for 71-15 All with auto AC which would be applicable to 1976 as well. 

 

NOS-OEM-Genuine-GM-Delco-7935324-15-7528-Ambient.jpg.df24c61857b5fd1d2635cb6944b5a3d3.jpg20220507_170038.jpg.86146dbb140129f77380f9c509f23e43.jpg20220507_170056.jpg.89752e595499fb9a5ea46dc2e4856462.jpg

Edited by 76CX39 (see edit history)
  • Like 1
Link to comment
Share on other sites

In the earlier automatic a/c systems, GM used a "Programmer" mechanism, under the instrument panel, which was the control module "central" for the system.  Usually, if everything else was in good condition, but it just didn't operate correctly, THAT mechanism was the issue, by observation.  This would be for the "Comfortron" systems, which were reasonably common between the carlines in the full-size vehicles.

 

That Comfortron system probably did have a separate manual or a section of the Body Service Manual, at some point in time.  Plus some TSB updates on changes when they might have happened.  Being that we had just Chevrolet back then, very few of those systems were ordered by us.  They would be more common in Oldsmobiles, Buicks, and (especially) Cadillacs, back then.  As far as I know, only in the B/C series platforms.

 

Enjoy!

NTX5467

Link to comment
Share on other sites

Posted (edited)

40BFEE49-9BD7-4B36-A8C0-D88D063D8975.jpeg   @76CX39 this page is from a 1976-1977 Buick Chassis and Body parts catalog effective June 1977, the ambient sensor 

part # 9349024 for 76 C,E w/A.C. (C-61)  I hope this helps,

Bob

 

 

Edited by NailheadBob
added information (see edit history)
  • Like 1
Link to comment
Share on other sites

Thank you NailheadBob! Well of course! It was in front of my nose all along! I just kept looking under sensor and resistor didn't bother to look through the entire listing under 9.275 because I was expecting it under SENSOR, Ambient or something like that. Feel sheepish, on the other hand why it was listed like that no idea. Both the Cadillac and the older Buick catalog list it as one would expect it under the SENSOR, xxx entry. 🙄

Link to comment
Share on other sites

Posted (edited)

On the Chevrolet side of things, it seemed that all of the hot rod engine parts were mentioned in some of the hot rodder magazines, BUT as I later discovered, they were in the Chevy parts book all of the time, hiding in plain open sight.  No option codes or similar, but with their own engine description nomenclature.  AND had been that way since 1955!

 

For example . . . 350 w/2bbl was the 250 horsepower V-8, 350 w/4bbl was the 295-300 horsepower V-8, 350 w/HPE (high perf engine) was the 350 horsepower V-8, 350 w/SHPE (special high perf engine) was the 370 horsepower V-8 aka LT-1, 427 w/HD was the L88.  ONCE you understood what you were looking at, it was all there, not hidden except to those who did not know what they were looking at.  BUT this was also back in the times when a good Chevy parts person had a lot of product knowledge!  Other than camshafts and pistons, each of those 350 engines had unique cosmetic differences which would give away their true identity.  Additionally, you could track the other things like distributor and carburetor part numbers for additional information.  IF they had been changed, then you went to the block stampings on the ID pad to see how it left the engine plant.

 

In the case of the thin plastic "cam" below the metering rod hanger on QJets, they are listed in some model years and not others, even some particular car lines and not others, by observation.  They also can be a "wear item" which will need to be replaced over time, too.

 

So, sometimes you have to read between the lines, so to speak.

 

Just some thoughts and experiences,

NTX5467

Edited by NTX5467 (see edit history)
Link to comment
Share on other sites

There used to be a time when one of the guys sitting at the break table would be a Ham Radio operator. He would tell you it was a Wheatstone bridge and what to ask for at Radio Shack to fix it. The guy is hard to find and the Shack is gone.

 

I do have four resistors in an old five pack if anyone would like to cheat the "chip" in a GM key. And I am not even the Ham guy.

  • Haha 1
Link to comment
Share on other sites

I just took a little poetic license on the key resistance comment. Automotive design uses so many common and reliable methods that most can be reverse engineered to find an off the shelf part to replace even the most elusive parts.

 

The '94 Roadmaster that I did the key job on also had a direct drive starter I installed that cured a random starter engagement problem. And a piece of black electrical tape over the anti-lock brake light since it was hydraulically disconnected from the system. ("Whats that piece of tape for?" "Don't worry, don't touch it.").

 

I gave it to a needy friend and had more than a couple of calls from the shop he took it to.

  • Haha 1
Link to comment
Share on other sites

8 hours ago, 60FlatTop said:

And a piece of black electrical tape over the anti-lock brake light

When my father was living in Tennessee he had a buddy that owned a used-car lot.  He upped the game when it came to defeating MIL and ABS lights.  His method was to drill a small hole through the lens and the cluster mask.  He then stuck a small nail or awl into the hole and used it to smash the bulb, extinguishing the light.  I suppose that tiny hole is less noticeable than black tape on the lens...  :unsure:

Link to comment
Share on other sites

"Yankee Ingenuity" at its best . . . until it might be time for the state emissions/safety inspection, which requires a code check.  BUT while it lasts . . .

 

NTX5467

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...