Rear Defroster Doesn't Work
12-25-04, 05:36 PM
#1
Driver School Candidate
Thread Starter
Join Date: Jun 2003
Location: California
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Rear Defroster Doesn't Work
I bought my car 2 years ago and when I turn on the rear defroster only the outside rear view mirrors heat up quickly. But the windows in the back stays foggy. At first I thought that it just took awhile and I dont take long trips but the outside mirrors work quick. And the rear windows does have tint on it but I bought it like that. So i haven't touched it. Can anyone tell me what I can do may be there is a fuse I can look at (but I would think that the outside mirrors would not work if a fuse were blown). 
12-26-04, 08:37 AM
#3
Driver
Join Date: May 2001
Location: Atlanta, GA
Posts: 167
Likes: 0
Received 0 Likes
on
0 Posts
I had exactly the same problem. My side mirrors would defrost just fine, but the rear window wouldn't do anything. From the wiring diagram that I looked at, both the side mirror and rear defrosters are fed from the same fuse so that wasn't the problem. However, just to make sure, you can locate the connections for the rear defogger that are under the trim on the passenger side of the rear glass. Be careful when you pull back that trim piece or you'll break it like I did. With the rear defroster turned on, you should get 12 V across those contacts.
If you get voltage, the problem must be in the defroster element. The element should have a low resistance when measured with an ohm meter. Of course, remember to turn off the defroster before hooking your ohm meter up to these contacts. I'm not sure what that resistance should be, but it's got to be less than 10 ohms since that element is supposed to heat up the rear window enough to defog it. If you show an open circuit (infinite resistance) like I did, your defogger element is broken.
I was quoted $1200 from my favorite glass place to replace the rear window. Like most people on this forum, I don't just whip out the checkbook to solve problems. After all, that's why we're here, right? I got some conductive paint that is supposed to fix breaks in defroster elements, but it didn't help. It might fix your problem if you only have a couple of broken element traces that are easily located. Finally, I ordered a replacement defroster from www.frostfighter.com. It was about $50. I figured if I put it on and it didn't work or looked bad, I could always replace the window later.
If you decide to try this, let me give you a couple of pointers:
1. I ordered the 12 line kit, but I wish I had ordered the 16 line kit. You get more of the raw grid material to work with, and you don't have to use it all.
2. Carefully evaluate where you want to position the grid before you start. There's no turning back once you stick the first set of grid lines on the window. Also, the spacing of the grid lines is dictated by the electrical connectors you have to work with. You can't spread them out like I thought I could.
3. The instructions are not too clear on this point, but the only material left sticking to the window when you're finished are the copper grid lines. The paper backing that is used to apply the grid lines comes off completely, and there is no transparent material left adhering to the window. I spent 30 minutes trying to peel the paper backing away from something that wasn't there. This will become more clear when you see what you have to work with.
4. You are given electrical components to work with including a timer and switch. You won't need those. Just hook the new grid up to your old defroster connections so you can use your existing circuitry.
Overall, the end result doesn't look bad at all. You would need to be looking for the new grid to notice it even though it doesn't follow the same contour as the existing grid.
If you get voltage, the problem must be in the defroster element. The element should have a low resistance when measured with an ohm meter. Of course, remember to turn off the defroster before hooking your ohm meter up to these contacts. I'm not sure what that resistance should be, but it's got to be less than 10 ohms since that element is supposed to heat up the rear window enough to defog it. If you show an open circuit (infinite resistance) like I did, your defogger element is broken.
I was quoted $1200 from my favorite glass place to replace the rear window. Like most people on this forum, I don't just whip out the checkbook to solve problems. After all, that's why we're here, right? I got some conductive paint that is supposed to fix breaks in defroster elements, but it didn't help. It might fix your problem if you only have a couple of broken element traces that are easily located. Finally, I ordered a replacement defroster from www.frostfighter.com. It was about $50. I figured if I put it on and it didn't work or looked bad, I could always replace the window later.
If you decide to try this, let me give you a couple of pointers:
1. I ordered the 12 line kit, but I wish I had ordered the 16 line kit. You get more of the raw grid material to work with, and you don't have to use it all.
2. Carefully evaluate where you want to position the grid before you start. There's no turning back once you stick the first set of grid lines on the window. Also, the spacing of the grid lines is dictated by the electrical connectors you have to work with. You can't spread them out like I thought I could.
3. The instructions are not too clear on this point, but the only material left sticking to the window when you're finished are the copper grid lines. The paper backing that is used to apply the grid lines comes off completely, and there is no transparent material left adhering to the window. I spent 30 minutes trying to peel the paper backing away from something that wasn't there. This will become more clear when you see what you have to work with.
4. You are given electrical components to work with including a timer and switch. You won't need those. Just hook the new grid up to your old defroster connections so you can use your existing circuitry.
Overall, the end result doesn't look bad at all. You would need to be looking for the new grid to notice it even though it doesn't follow the same contour as the existing grid.
Thread
Thread Starter
Forum
Replies
Last Post
