Author Topic: 1970 Deville Convertible rear window defroster  (Read 891 times)

Offline colorado4x4

  • Posts: 52
  • CLC Number: 59187374
  • Name: Nicholas Lundberg
1970 Deville Convertible rear window defroster
« on: September 20, 2019, 02:43:03 PM »
My understanding is that the rear window defroster was offered as an option on the 1970 Deville convertibles.  Anyone have this option on their 1970 Deville convertible? Was is blower set up, or was it an electrically heated rear window set up?  (I am guessing it was a blower set up, I don't think electrically heated windows came until later)

I have found a complete rear window defroster setup from a 1969 coupe deville parts car (dash switch, blower motor, ducting, etc.)and was wonder a few thing:
*would the main wiring harness already be set up for this option?  (i.e.; if I install the dash switch could I plug it into the existing wiring harness)
*How is the blower motor, ducting, etc., situated within the convertible top well?

With the opportunity, I am thinking of adding this to my newly acquired 1970 Deville convertible,  if doing so doesn't turn into a rube goldberg project!
1970 DeVille Convertible Chateau Mauve Firemist
1970 DeVille Convertible Lanai Green Metallic

Offline Cadillac Fleetwood

  • Posts: 919
  • Name: Charles Fares - Sadly Deceased Mid November 2021
Re: 1970 Deville Convertible rear window defroster
« Reply #1 on: September 20, 2019, 03:07:25 PM »
The 1970 DeVille convertibles offered a blower-type rear window defogger, as optional equipment.  The switch, which is identical to that used on the closed cars of 1969, fits to the immediate left of the convertible top switch.  Making the rear window defogger available on convertibles necessitated revising and relocating the convertible top switch in 1970.

The wire harness is not part of the factory body wiring.  It is considered "accessory wiring". The wire harness consists of wiring which incorporates a resistance wire, which provides the high and low speeds of the blower.  The dash switch and the wiring harness are identical among closed cars and convertibles. It draws power from a connection at the fuse panel.  The grille, distribution duct, and blower motor/mounting are exclusive to the convertible.  The grille and distribution duct used in convertibles are not as long (from side to side) as those used in the closed cars.

The blower motor mounts to the forward portion of the convertible top well. The rear seat  backrest (and the cushion also) needs to be removed in order to mount the blower and distribution duct.  The sheet metal has "dimples" which indicate where the holes are drilled.  The blower bracket uses sheet metal screws; the distribution duct has "J-clips" which accept oval head Phillips screws.  The distribution duct is shaped and positioned so that the grille is tilted rearward, causing the discharge air to be directed to the rear glass. The grille on convertible units is retained to the duct with Phillips-head screws, whereas on closed cars, there are clips instead.

There were no electrically-heated grid rear window defoggers on convertibles until the 1971 model year.

Edit:  The rear window defogger cost approximately $37 in 1970.  Even at that relatively modest cost, the accessory is rather scarce.

Charles Fares
« Last Edit: September 20, 2019, 06:04:32 PM by Cadillac Fleetwood »
Forty-Five Years of Continuous Cadillac Ownership
1970 Fleetwood Brougham
1969 DeVille Convertible
1989 Fleetwood

"The splendor of the most special occasion is rivaled only by the pleasure of journeying there in a Cadillac"

Offline 76eldo

  • Posts: 6655
  • CLC Number: 22443
  • Name: Brian Rachlin
Re: 1970 Deville Convertible rear window defroster
« Reply #2 on: September 20, 2019, 03:40:17 PM »
I’ve seen this option on a highly optioned 70 Deville convertible.
It’s prety cool. I love loaded up cars.
Brian Rachlin
Huntingdon Valley, Pa
CLC # 22443
I prefer email's not PM's rachlin@comcast.net

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Offline wrefakis

  • Posts: 805
Re: 1970 Deville Convertible rear window defroster
« Reply #3 on: September 20, 2019, 05:23:28 PM »
nice to have, my last off  the line 70 from the factory had the switch on dash, but was missing the blower!

Offline 69Deville

  • Posts: 195
  • Name: D Mirrione
Re: 1970 Deville Convertible rear window defroster
« Reply #4 on: September 21, 2019, 01:19:28 AM »
nice to have, my last off  the line 70 from the factory had the switch on dash, but was missing the blower!
Are those speaker grilles the originals in the original location? I've always been curious as to how the stereo speakers were handled in the convertible.
1969 Cadillac Deville Convertible

Offline Jim Govoni CLC 20546

  • Posts: 216
  • Madeline
  • CLC Number: 20546
  • Name: Jim Govoni
Re: 1970 Deville Convertible rear window defroster
« Reply #5 on: September 21, 2019, 12:18:28 PM »
Yes, the speaker grills are correct in the correct color.
1953 Series 62 
1966 Fleetwood 
1969 deVille Convert.
1941 Series 63

Offline colorado4x4

  • Posts: 52
  • CLC Number: 59187374
  • Name: Nicholas Lundberg
Re: 1970 Deville Convertible rear window defroster
« Reply #6 on: September 21, 2019, 03:14:24 PM »
Thanks for the detailed responses and photos.  I also like highly optioned old cars and think this might be an opportunity to add this rare option to my car, but sounds like I would need to find the specific blower motor, ducting and grill to fit in the top well.   I would think the 1969 Coupe Deville parts car that I have the opportunity to grab the dash switch and existing blower motor, ducting and grills would have the accessory wring harness also. Curious on the specific path the accessory wiring harness runs from the dash area to the rear of the car. 

If anyone has additional "behind the scenes" photos of what the blower motor, ducting and wiring setup looks like from underneath the convertible top well fabric, either from a behind the rear seat view or from the trunk view,  please post those.

Yep that is how the rear stereo speakers are situated in the 1970 convertible, they are housed in cardboard type boxes on either side underneath the convertible top well fabric
1970 DeVille Convertible Chateau Mauve Firemist
1970 DeVille Convertible Lanai Green Metallic

Offline spolij

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  • Name: John Spolidora

Offline cadillacmike68

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  • Still crusin'
  • CLC Number: 15823
  • Name: M Santos
Re: 1970 Deville Convertible rear window defroster
« Reply #8 on: September 22, 2019, 08:06:55 PM »
That's real nice to have up in the snow belt. My 1970 Fleetwood Brougham had the rear de-fogger and it actually melted snow and ice but it did take a while.

What's needed down here is a 90% light rejection titanium tint on the glass - which I have.
Regards,
"Cadillac" Mike

Offline Scot Minesinger

  • Posts: 6004
Re: 1970 Deville Convertible rear window defroster
« Reply #9 on: September 22, 2019, 10:07:07 PM »
I have the rear defogger on my 1970 SDV, but of course this beauty is garage kept and only driven in nice weather.  This option will never be needed in my use of the Cadillac, nor likely any future owner would use it either.  I don't participate in any shows that would require me to demonstrate operation, so I never even tried it to see if it works.  IMO not a worthwhile option to add.  Tilt wheel, trunk release, and auto headlight turn on are must add options if not so equipped on a 1970 Cadillac.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

 

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