News: Putting FUN and FRIENDLINESS, FIRST into owning and learning about AMC small bodied cars, primarily Eagles, Spirits and Concords as well as vehicles built in AMC's Mexican subsidiary, VAM.

The AMC Eaglepedia can now be accessed using the buttons found below  This is a comprehensive ever growing archive of information, tips, diagrams, manuals, etc. for the AMC Eagle and other small bodied AMC cars. 

Also a button is now available for our Face Book Group page.


Welcome to the AMC Eagles Nest.  A new site under "old" management -- so welcome to your new home for everything related to AMC Eagles, Spirits and Concords along with opportunities to interact with other AMC'ers.  This site will soon be evolving to look different than it has and we will be incorporating new features we hope you will find useful, entertaining and expand your AMC horizons.

You can now promote your topics at your favorite social media site by clicking on the appropriate icon (top upper right of the page) while viewing the topic you wish to promote.


  • March 28, 2024, 10:46:21 AM

Login with username, password and session length

Author Topic: Rear Defrost Issue 12v Showing On the Glass But No Heat  (Read 4316 times)

0 Members and 1 Guest are viewing this topic.

Offline Beaverseagle

  • Eagle
  • **
  • Posts: 107
  • Thumbs Up 8
Rear Defrost Issue 12v Showing On the Glass But No Heat
« on: January 11, 2016, 09:28:52 AM »
Anyone have this issue?  I'm getting 12v on the hatch and all the painted lines.  I don't see any brakes, but still no heat.


82 SX/4
82 SX4 258 w/ 2 inch lift 235 tires and TBI kit.

Offline rollguy

  • Turbo Diesel Eagle
  • AMC Eagles Den Addicted
  • ********
  • Posts: 1797
  • Thumbs Up 84
  • Southern California
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #1 on: January 11, 2016, 10:46:24 AM »
Are you testing for power at both connections to the glass?  You can also test it with a light bulb by disconnecting the - side connection and wiring a bulb between the wire going to the glass and ground.  If the bulb lights up, you are golden. You can also remove both wires and use a meter to check continuity.  Also, you may not be able to feel any heat for a while, even if it is working properly.
1980 Eagle Turbodiesel Wagon (only 2 known to exist as of 2008)- 7-7-2011 Flight to it's new nest @ Rambler Ranch
1983 Eagle Wagon  Tan over Copper
1982 Eagle SX4 "ALTREGL"  (avatar photo)
1982 Eagle 4 Door Sedan  Copper over Satin Black
1985 Eagle Sport Wagon October 2007 ROTM (SOLD)
4 Biofuel powered Benzs ('98 E300, '82 300 CD, '82 300 TD (wagon), '80 240 D)
1983 GMC Van (6.2 Diesel)
1985 Mitsubishi pickup (2.3 Turbodiesel)

Offline Beaverseagle

  • Eagle
  • **
  • Posts: 107
  • Thumbs Up 8
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #2 on: January 11, 2016, 11:23:20 AM »
I didn't disconnect anything.  I turned the switch on at the front and took a multimeter and touched the positive lead to all relevant connections on the glass (connections at each end of the painted lines and the painted lines) and grounded the black lead to the body.  I was getting 12v every where.  When I turned off the switch, I got no reading.

It was very cold this weekend and I drove around with it on for long periods of time and nothing melted.  The timer on the defrost switch did go off but only after 10 minutes.  Is my testing incorrect? 

My logic is if I get 12vs there should be heat!  But I guess not because I'm not getting anything.

As you can tell, electronics are my thing.  :banghead:
82 SX4 258 w/ 2 inch lift 235 tires and TBI kit.

Offline AMC of Houston

  • The only thing we learn from history is that we don't learn from history.
  • Global Moderator
  • Eagle Sundaancer
  • *****
  • Posts: 893
  • Thumbs Up 86
    • American Motors Club of Houston
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #3 on: January 11, 2016, 01:03:16 PM »
Those tests won't tell you if the ground is good.   My waggie had a broken ground wire (broken inside of the insulation from flexing with the opening/closing of the hatch).
George G.
'81 Eagle Sundancer
'85 Eagle Waggie
1960 1902 Rambler Replica
'64 American
'70 AMX (Big Bad Blue), '70 AMX (White)
'77 Gremlin
'78 Pacer Coupe, '78 Pacer Wagon
'79 Pacer Wagon
'73 Jensen Interceptor
'86 Audi 5000 Turbo
'98 Aston Martin DB7
'09 Nissan Titan
'10 Nissan Maxima

Offline macdude443

  • Eagle Sport
  • ****
  • Posts: 463
  • Thumbs Up 24
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #4 on: January 11, 2016, 03:09:39 PM »
Those tests won't tell you if the ground is good.   My waggie had a broken ground wire (broken inside of the insulation from flexing with the opening/closing of the hatch).

My thoughts exactly.  The only really good ground reference for that test is after the lead terminates at the hatch.  My rear defrost didn't work either and I found the braided lead had broken inside the rubber insulation near the left hatch hinge.  I also don't think the switch will engage without a complete circuit.  I know mine will not, but I have the later style all-in-one defrost switch, not the early one with the push button.
1982 Eagle SX/4
1986 Eagle Wagon

Offline rommel1940

  • Eagle
  • **
  • Posts: 93
  • Thumbs Up 2
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #5 on: January 11, 2016, 03:24:33 PM »
Mine isn't working ethier, my 84 limited has a lighted rocker switch, witch lights up when on, but after a long drive , it doesn't seem to be heating/ no affect.
1984 Eagle Limited

Offline rommel1940

  • Eagle
  • **
  • Posts: 93
  • Thumbs Up 2
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #6 on: January 11, 2016, 03:49:36 PM »
Well for giggles,  I checked and have no voltage at rear glass, no broken wires . I'm guessing its my defrost switch, because it seems funky, it will only come on if you really push on it it, I'll swap one out of a parts car soon, when I do my radio pod switch
1984 Eagle Limited

Offline JayRamb

  • ELLA THE EAGLE & EDWIN THE EAGLE
  • Eagle Sundaancer
  • ******
  • Posts: 946
  • Thumbs Up 30
  • AMC passion for over 32 years. BIG advocate!
    • UPDATED!!  1967 Rambler Rebel weebly website
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #7 on: January 12, 2016, 03:26:25 PM »
Both of my wires on each side of the hatch were broken off from opening and closing
Jayson H.
Best HWY Mileage of 87 Eagle:  26.2 MPG

Believer in AMSOIL & Seafoam
1987 Garnet Red Eagle Wagon: 70,500 miles
1967 Rambler Rebel 4 Door 290 V8 (original family car) Marina Aqua 142K miles
1985 Eagle Wagon in Autumn Brown 74,800 miles as my daily driver
SOLD 1984 Black Eagle Limited w/Tach & gauge cluster: 245,100 miles SOLD

Offline Beaverseagle

  • Eagle
  • **
  • Posts: 107
  • Thumbs Up 8
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #8 on: January 22, 2016, 02:42:24 PM »
Bingo. That was the issue. One of the wires broke inside the black wire casing.  Working great now!
82 SX4 258 w/ 2 inch lift 235 tires and TBI kit.

Offline vangremlin

  • Administrator
  • AMC Eagles Den Addicted
  • ******
  • Posts: 4411
  • Thumbs Up 212
Re: Rear Defrost Issue 12v Showing On the Glass But No Heat
« Reply #9 on: January 22, 2016, 04:53:39 PM »
Bingo. That was the issue. One of the wires broke inside the black wire casing.  Working great now!

Good to hear!
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

 

SMF spam blocked by CleanTalk