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Author Topic: 75CDV coolant temperature switch  (Read 628 times)

Offline jaydog

  • Posts: 28
  • CLC Number: 14702
  • Name: J.D'Angelo
75CDV coolant temperature switch
« on: September 22, 2018, 02:03:58 PM »
Can't seem to find this switch which is supposed to be under the AC compressor.  No parts listing anywhere..earlier threads did not reveal a source.  Anyone have an idea?  I need some notification of overheating as it gets quite hot here in Las Vegas as you might guess.

Re: 75CDV coolant temperature switch
« Reply #1 on: September 22, 2018, 05:05:43 PM »
This is what you are looking for.
I think I bought the last two in existence, but I may be wrong.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline jaydog

  • Posts: 28
  • CLC Number: 14702
  • Name: J.D'Angelo
Re: 75CDV coolant temperature switch
« Reply #2 on: September 22, 2018, 05:22:38 PM »
Thank you

Offline 76Caddy

  • Posts: 73
  • Name: Tim Plummer
Re: 75CDV coolant temperature switch
« Reply #3 on: September 22, 2018, 09:46:59 PM »
Jaydog,

I replaced the one on my '76 Brougham a few months ago and I had to remove the A/C compressor to get to it.  I walked into my local NAPA store and they had one on the shelf.

Tim
Tim Plummer
CLC #18948
1967 Eldorado
1976 Brougham
1976 Seville

Offline The Tassie Devil(le)

  • Administrator
  • Posts: 12424
  • CLC Number: 18992
  • Name: Bruce Reynolds
Re: 75CDV coolant temperature switch
« Reply #4 on: September 22, 2018, 10:01:17 PM »
Not sure, but could it be the same switch for all the GM brands?

Nothing would surprise me.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Offline Scot Minesinger

  • Posts: 6004
Re: 75CDV coolant temperature switch
« Reply #5 on: September 23, 2018, 08:32:37 AM »
Yes you have to remove the ac compressor to get to this switch, and sometimes the switch thread seals leak a little on original cars so it is a good idea to reseal them anyway.  These switches make ground, so look for compromises in wire insulation too during replacement.  These are available still, look at Rock Auto and other auto parts sources.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline The Tassie Devil(le)

  • Administrator
  • Posts: 12424
  • CLC Number: 18992
  • Name: Bruce Reynolds
Re: 75CDV coolant temperature switch
« Reply #6 on: September 23, 2018, 08:39:57 AM »
When you reseal these threads, don't use plumbers thread tape, as you run the risk of not getting a grounding on the thread of the fitting to the block, and if this happens, the sender will not work.

Use a thread paste.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Re: 75CDV coolant temperature switch
« Reply #7 on: September 23, 2018, 10:39:23 AM »
For al;l you guys that say the sensor/switch is still available, have you looked today?
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline TJ Hopland

  • Posts: 10193
Re: 75CDV coolant temperature switch
« Reply #8 on: September 23, 2018, 02:11:17 PM »
I think the Cadillac sensor was a 1/2" thread.  I believe 3/8" was much more common.   If they are getting hard to find maybe a thread adapter would let you use a more common one?   

I found one using an old school book that listed the different sensors by things like thread size and temp.   It turns on a little sooner than the original one which I like, you get a hint that a problem may be coming vs it may be too late with the OE sensor.    Minor issue with that one is apparently there is about a 10% tolerance in the temp so you can end up with one that comes on sooner than you would like it to.   I don't have the part number handy, its in at least one thread here and I may still have a spare in my parts stash.   If I remember I will look later.     
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

Re: 75CDV coolant temperature switch
« Reply #9 on: September 23, 2018, 05:20:09 PM »
There seems to be a bit of confusion as to the actual function of this sensor.  It is activated (circuit is closed) when the temperature of the bulb reaches 260 degrees F.  Now the only way that can happen with a 15-16 pound pressure relief cap and a 50/50 mix of antifreeze/water is if the vapor is super-heated. The only way there would be space for vapor and temperature enough for super heat is if the coolant is low, allowing the vapor to come in contact with the hot metal inside the water jacket. THUS, this sensor is a low coolant indicator, rather than a temperature warning.
For this system to work in any manner it was intended, the correct (not close) sensor is required.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

 

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