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Greengobster
Samba Member
Joined: September 01, 2011
Posts: 24
Location: Ramstein, Germany
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 Posted: Tue Nov 08, 2011 5:57 am Post subject: Rear Defroster on 1975 Bug |
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So I have no idea how to get the rear defroster to turn on on my 75 bug. Any one have any ideas what this toggle switch goes to? As far as I can tell it has no effect no matter what position it is in.....
Here is a pic of the dash, the lower red knob closest to the steering wheel has been wired for the windshield washer. |
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glutamodo 
The Android
Joined: July 13, 2004
Posts: 26583
Location: Douglas, WY
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| Posted: Tue Nov 08, 2011 6:43 am Post subject: |
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That's the switch, and it operates a relay under the rear seat, bolted to the floorpan. There is an inline fuse down there too.
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19super73
Hardcore Stock Nazi
Joined: October 18, 2007
Posts: 4351
Location: Cité Soleil
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gt1953
Samba Member
Joined: May 08, 2002
Posts: 13957
Location: White Mountains Arizona
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| Posted: Tue Nov 08, 2011 12:24 pm Post subject: |
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Check for voltage at the connections at the grid.
_________________
Volkswagen: We tune what we drive.
Numbers Matching VW's are getting harder to find. Source out the most Stock vehicle and keep that way. You will be glad you did.
72 type 1
72 Squareback
({59 Euro bug, 62, 63, 67, 68, 69, 73 type ones 68 & 69 type two, 68 Ghia all sold}) |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17639
Location: Left coast, Canada
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| Posted: Wed Nov 09, 2011 12:41 am Post subject: |
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Before you waste any time, put an ohm meter across the whole grid. I guarantee your 35 year old grid will measure in the MΩ range instead of less than 20Ω.
If this is what you find, you need a new window first. Playing with the wires is futile.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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Greengobster
Samba Member
Joined: September 01, 2011
Posts: 24
Location: Ramstein, Germany
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| Posted: Wed Nov 09, 2011 2:47 am Post subject: |
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| I replaced the fuse this morning and still no defrost. Bruce I will check the grid on the rear window this afternoon, I am not getting my hopes up at this point. Where is the relay for the defroster? I have two relays in the fuse box, one is the flasher the other I am not sure what it is... |
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glutamodo
The Android
Joined: July 13, 2004
Posts: 26583
Location: Douglas, WY
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| Posted: Wed Nov 09, 2011 8:14 am Post subject: |
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Like I said before...
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| it operates a relay under the rear seat, bolted to the floorpan. |
This is out of a later owner's manual, the fuseholder locaction may be not be strapped to the insulation of the heater duct at this point, but the relay location shown is the same:
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Greengobster
Samba Member
Joined: September 01, 2011
Posts: 24
Location: Ramstein, Germany
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| Posted: Wed Nov 16, 2011 2:51 pm Post subject: |
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| Well I ohmed out the Rear defroster and it read 4k Ohms. I am not sure if this is to high. I have power at the terminal with the in line fuse from the relay but not any where else. I think I might try replacing the relay and see from there. Any thoughts? |
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glutamodo
The Android
Joined: July 13, 2004
Posts: 26583
Location: Douglas, WY
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| Posted: Wed Nov 16, 2011 3:14 pm Post subject: |
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4000 ohms is way too high of resistance. That would generate about .04 Watts of heat... Probably a bad defroster grid, not unusual on something that old.
So that relay is probably not the problem, or at least, not the only problem. Did you check the black wire going to terminal 86, it is the one that comes from the toggle switch under the dashboard, it should go to +12V when you turn the key on and flip the switch.
-Andy |
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VeedubPastor
Samba Member
Joined: September 03, 2009
Posts: 761
Location: Maryland
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| Posted: Wed Nov 16, 2011 5:13 pm Post subject: |
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You could always put a new grid on your current glass. These guys have a kit.
http://www.frostfighter.com/index.htm
_________________
1971 Super Beetle - Daily Driver
Solex H30/31 & 034 distributor (yeah, I know)
Stock thermostat & flaps
Stock air cleaner and emissions equipment |
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jwold
Samba Member
Joined: September 30, 2008
Posts: 2088
Location: Portland, OR
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| Posted: Wed Nov 16, 2011 6:10 pm Post subject: |
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On previous posts I've read you can still get replacement rear windshields with a new grid.
I installed a frostfighter, it's working fine, but it stays on too long and since I'm still running a generator, it makes my wipers pretty slow.
Alternator...probably no problem. |
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VeedubPastor
Samba Member
Joined: September 03, 2009
Posts: 761
Location: Maryland
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| Posted: Wed Nov 16, 2011 8:00 pm Post subject: |
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| jwold wrote: |
| On previous posts I've read you can still get replacement rear windshields with a new grid. |
http://www.mamotorworkstv.com/vw/product/rear-window-glass-with-defroster/
_________________
1971 Super Beetle - Daily Driver
Solex H30/31 & 034 distributor (yeah, I know)
Stock thermostat & flaps
Stock air cleaner and emissions equipment |
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