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81 CDV

Started by 6caddy2, March 01, 2020, 11:46:30 AM

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6caddy2

Blower motor resistor module has gave out, anybody rebuilding these? I have of course checked with the usual "suspect" places, but not liking what I see as usual, wondering if anybody might know where to try and source this part and or throw me on a good lead for said part?!
                                                                                                                                                                                         
Thank you for any info and or help with this, Joe
1962 convertible
1979 Fleetwood brougham d'Elegance
1981 Coupe deVille 368 FI 864
1996 Fleetwood Brougham
SOLD- 1978 sedan deVille

Dave Shepherd

#1
Pretty sure Rockauto has one, checked didn't see one, but are a few around on E bay, Google it.  But usually the blower motor overloads them and causes the failure. So replace the blower also.

TJ Hopland

These days I would not trust a replacement blower any more than an original unless its for sure bad.   Check the manual for a blower test.   They will usually have an amp draw specification and usually also a way to test without an amp meter.   It may say something like do a temp setup with a 15 amp fuse and if it lasts for 5 mins its good.

I don't think anyone is fixing them and aftermarket never made them for the earlier cars so they have always been expensive.   Lots of one year one model modules in the early years.    Later they seemed to settle on a design that lasted a few years and had aftermarket support.

First hurdle in fixing them is they are potted which is where they basically pour an epoxy like material over the entire circuit board and its components.   Most of the time the only way to remove it is very carefully with small hand instruments.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

6caddy2

Dave thank you for the info1

TJ, 1st thing off the bat that I looked at was my manuals for it and the trouble shooting section, did a diag. on the climate control "head unit" according to the TS section, checked out ok, then next to the blower motor as Dave mentioned, ok there all the way around, next was the blower motor resistor, which in this case, by way of year and model is the most likely culprit, and your right, by the later year of 82 Cadillac "GM" had settled on a resistor that proved better and preformed much better in the HVAC system of these cars!

I can do a lot of work on my cars, but not going to dive into that resistor, going to have to bow down to the place that will take mine as a core and pay the "price" for a rebuilt unit, but at least they give a warranty with this, rather than, "it worked when pulled from car" warranty :o!
                                                                      Thanks again for the response's! Joe 
1962 convertible
1979 Fleetwood brougham d'Elegance
1981 Coupe deVille 368 FI 864
1996 Fleetwood Brougham
SOLD- 1978 sedan deVille

TJ Hopland

The 70's and I presume earlier auto climate control units used actual resistors.  The system was pretty much the same as the manual systems with a multi position switch that linked in and out various resistors to control the fan speed.  The auto part was just a vacuum servo that moved the switch.     

The 'digital' (80's and up) ones I have been able to see in have what I assume is a triac in either a TO3 or T048 package on the heat sync.   I just had to buy one for my 90.   The one that failed I could not identify any components and the potting material was very hard.   Aftermarket replacement had a big visible TO3 package device that was visible which I am assuming is a more old school design using 'off the shelf' components.   The failed one I assume is original and possibly used some somewhat custom components.    Is/was either one of them built for quality?  Who knows.   


If they are asking for a core you would assume they are repairing them.   If they have a lot of experience with them they may know where to go so they don't have to de pot the whole thing.    Another thing that is made difficult by the potting and removal process is being able to identify parts.  Markings can be hard to read or damaged by the process so if you don't have documentation to go by it can really slow down the reverse engineering and troubleshooting process.

I used to repair equipment that was potted similar to these and in those the failure was always the same component.   Someone had come up with a repair kit that included a paper template and a special drill bit you would use to get access to what you needed to replace.   Took longer to get the module out of the equipment than it did to make the repair.

I would assume with these either they are not doing enough to come up with a system or the failures are not consistent enough to come up with a system so that is why the cost is still high.  Its likely mostly labor just to gain access to the failed part or parts.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

6caddy2

These where my thoughts as well sir, the part is original to the car, as being an 81 CDV and having the new style "Electronic Climate Control" dash unit for this model year as the "Digital Age" was coming into it own rights, these units preformed very well as did the blower motor which was used thru out a very wide range of the "GM" line up covering a good time frame of production, but as you stated the resistor is this case was of somewhat custom design for this model year and not just the "model" itself, so it is the weakest link in my system, who knows Monday made part or a Friday made part?!

The "potting" material was a good design in the aspect of to protect the "IPCB" from the under hood elements even though it is installed inside the HVAC box mounted to the firewall, giving it some protection from the under hood elements.

Being able to obtain a 'Delco Electronics" schematic showing what parts this platform was built with i.e. resistors, diodes and capacitors and the likes I would take a stab at repairing it myself, but only having an ohm's meter on my bench is where my range extends to. But with it I'm able to at least find out what "part' is failing or has failed in this case, a man has got to know his limitations! :o >:( ;D, or at very best where to seek knowledge as to how to repair or where to go for said repair of failed part, which would as you "stated" its likely mostly labor just to gain access to the failed part(s), hence the cost of the rebuilt part. And of course with the age of the part and not enough failed parts, there is not enough demand for this part calling for a better "after market" part being made better by upgrading the component(s) that are or will fail with time or useage ;)

At least I have a source to obtain a rebuilt OEM part with warranty, I do however have another option, and that would be to "jerry rig" the system by way of toggle switch on/off for a/c compressor and a 3 position switch low/med/high for the fan but I think that would lead to more problems down the line at some point :o!

So I'm going to go with the rebuilt one, keep fingers crossed and see how this part works, will update when said part is installed, and it's a very easy part for myself to R&R.

1962 convertible
1979 Fleetwood brougham d'Elegance
1981 Coupe deVille 368 FI 864
1996 Fleetwood Brougham
SOLD- 1978 sedan deVille

TJ Hopland

I have never looked at what the signal is coming from the programmer on these.   I wonder how hard it would be to build something to read it then operate relays to connect old school resistors?    Likely not worth the trouble for a $200 part.   If it was a $1000 part maybe.  Or just for a fun project....
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

6caddy2

It would be a fun project to explore, when in my later years and as these cars become older as I will be and maybe more need for this part would arise... but for now it is a $200 part as you stated that is available to me now as my time is being needed for preparing 2 Cadillacs for a car show in Vegas in April and the GN's in Kansas this year,  and as we all know here, so many caddy's and so little time, it just clicks off so fast!!  ??? >:( ;D
1962 convertible
1979 Fleetwood brougham d'Elegance
1981 Coupe deVille 368 FI 864
1996 Fleetwood Brougham
SOLD- 1978 sedan deVille