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djkeev
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Joined: September 30, 2007
Posts: 32625
Location: Reading Pennsylvania
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 Posted: Sat Jul 10, 2021 5:02 am Post subject: Electrical Overheating and fires in A/C wiring? |
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When I got my 90 Tintop with rear mounted "Factory" Air Conditioning, the A/C did not work. Nothing..... dead.
Upon investigation I found that the wiring in the left rear "D" Pillar had burned.
Someone had made rudimentary repairs at some point after the fire.
I posted my findings in my “Rebuild 90 Tintop A/C" thread and mentioned it in my Van build thread too.
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0
My initial post mortem diagnosis was an over heated blower fan relay melting and actually bursting into flame.
The flame burned its way up the D pillar taking wire, insulation and plastic with it.
It melted the Pillar cover and charred a bit of wiring.
My initial suspect for causing this was the blower fan motors seizing causing excessive heat build up.
Upon opening the Evaporator housing I found the fans in decent shape, though I wasn't the first in there post fire.
And then a new member chimed in that he makes upgraded A/C harnesses that VanCafe sells (though their web site makes no mention of such a product)
Page 6 has the upgraded wiring loom discussion.....
https://www.thesamba.com/vw/forum/viewtopic.php?t=748346&start=100
There was brief chatter about exactly what caused the fire with no definitive conclusion.
Wire size is suspect
Relay size rating is suspect
And the member making the harness fell quiet offering no more information.
I spent a bit of time searching online for Vanagon A/C fires and found very little.
So, I thought that a thread dedicated to Vanagon A/C fires might gather interest and answers.
Plus, does anyone have experience with having a fire?
Dave
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Last edited by djkeev on Sat Jul 10, 2021 6:48 pm; edited 1 time in total |
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jlrftype7
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Joined: July 24, 2018
Posts: 3581
Location: Chicago
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| Posted: Sat Jul 10, 2021 7:23 am Post subject: Re: Over heating and fires in A/C wiring? |
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Have you run the blower with an amperage meter measuring amp draw at various speeds? I’d be curious to see what a decent, lubed blower pulls compared to one that’s never been serviced.
Is the relay feeding the blower and nothing else?
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'68 Westy- my first VW and vehicle/Bus- long gone.- sold it to a traveling Swiss couple....
'67 Type 3 Fastback, my 2nd car- gone
'69 Semi-Auto Stick Shift Beetle-gone
2017 MINI Coopers, our current DDs
‘84 Tin Top - Hilga....Auto |
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dgbeatty
Samba Member
Joined: October 26, 2006
Posts: 702
Location: Sacramento
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| Posted: Sat Jul 10, 2021 8:14 am Post subject: Re: Over heating and fires in A/C wiring? |
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Dave, there are a few problems with the design/implementation of the rear mounted A/C. In no particular order.
1. The low speed radiator fan is controlled by the overloaded multi function relay. Solution: add a relay under the dash to remove the load. This in itself will reduce the heat and some of the wiring damage.
2. Loose the strip fuse replacing it with a MIDI fuse. Same for the 2 x 20 ATOs.
3. Increase the 4mm² wiring with 6mm² as was done in SA.
4. A very careful study of the diagrams will reveal errors. Whereas the blowers are shown to have seperate connections for each blower in truth both blowers share combined connectors thus pushing a 40amp load thru 6.3mm terminals, bad juju. Solution: seperate into individual connectors as designed.
There is more
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kamzcab86
Samba Moderator
Joined: July 26, 2008
Posts: 7922
Location: Arizona
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| Posted: Sat Jul 10, 2021 8:37 am Post subject: Re: Over heating and fires in A/C wiring? |
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| dgbeatty wrote: |
Dave, there are a few problems with the design/implementation of the rear mounted A/C. In no particular order.
1. The low speed radiator fan is controlled by the overloaded multi function relay. Solution: add a relay under the dash to remove the load. This in itself will reduce the heat and some of the wiring damage.
2. Loose the strip fuse replacing it with a MIDI fuse. Same for the 2 x 20 ATOs.
3. Increase the 4mm² wiring with 6mm² as was done in SA.
4. A very careful study of the diagrams will reveal errors. Whereas the blowers are shown to have seperate connections for each blower in truth both blowers share combined connectors thus pushing a 40amp load thru 6.3mm terminals, bad juju. Solution: seperate into individual connectors as designed.
There is more |
As I've mentioned elsewhere, when I had to replace the high-low pressure switch due to an internal freon leak, which leaked into the wires and relays, I discovered VW superceded two of the relays with higher amperage versions (not that this is the source of fires, but it could be a contributing factor as the original relays age/wear).
Part numbers:
Photo of updated relays and such:
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~Kamz 
1986 Cabriolet: www.Cabby-Info.com
 1990 Vanagon Westfalia: Old Blue's Blog
2016 Golf GTI S
"Real knowledge is to know the extent of one's ignorance." - 孔子 |
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?Waldo?
Samba Member
Joined: February 22, 2006
Posts: 9752
Location: Where?
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| Posted: Sat Jul 10, 2021 8:57 am Post subject: Re: Overheating and fires in A/C wiring? |
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I got the engine/trans from a late model van that was gutted by a fire that started in the stock A/C wiring. The pics are harrowing:
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32625
Location: Reading Pennsylvania
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| Posted: Sat Jul 10, 2021 9:02 am Post subject: Re: Over heating and fires in A/C wiring? |
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| dgbeatty wrote: |
Dave, there are a few problems with the design/implementation of the rear mounted A/C. In no particular order.
1. The low speed radiator fan is controlled by the overloaded multi function relay. Solution: add a relay under the dash to remove the load. This in itself will reduce the heat and some of the wiring damage.
2. Loose the strip fuse replacing it with a MIDI fuse. Same for the 2 x 20 ATOs.
3. Increase the 4mm² wiring with 6mm² as was done in SA.
4. A very careful study of the diagrams will reveal errors. Whereas the blowers are shown to have seperate connections for each blower in truth both blowers share combined connectors thus pushing a 40amp load thru 6.3mm terminals, bad juju. Solution: seperate into individual connectors as designed.
There is more |
In regards to the wiring to each blower, my 1990 (very early, built the first month of 1990 production and has 1989 wiring features in the fuel injection) does have separate wires to each resistor and fan.
They become separate at the connection in the D pillar not far from the relays.
Each blower has a 100% separate feed up the D pillar and to each blower/resistor.
The shared load is only for a short distance, inches really, in the D pillar.
Dave
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http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
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https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
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blackglasspirate
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Joined: June 24, 2006
Posts: 1612
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| Posted: Sat Jul 10, 2021 11:30 am Post subject: Re: Overheating and fires in A/C wiring? |
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I haven't had a fire in mine but I did notice recently that the wires going into the body behind the driver's side tail light are burnt. I don't think anything actually caught fire, thankfully, but they got really hot at some point and feel...crispy.
I haven't investigated it any more than that because I removed most of the A/C when we hit the road to use the upper cabinet for storage, but if I ever do want to put it back in I'm going to have to do some major rewiring, not to mention new hoses and nearly everything else...
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Abscate
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Joined: October 05, 2014
Posts: 22668
Location: NYC/Upstate/ROW
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| Posted: Sat Jul 10, 2021 11:38 am Post subject: Re: Overheating and fires in A/C wiring? |
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Start by pulling each connector apart and making all metal shiny with a Dremel.
The bayonet style electrical connector is inferior in both its contact area and it’s ability to maintain pressure on the contact.
It then gets hot, oxidizes , higher resistance , more heat, repeat until fire hits
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crazyvwvanman
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Joined: January 28, 2008
Posts: 9935
Location: Orbiting San Diego
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| Posted: Sat Jul 10, 2021 11:49 am Post subject: Re: Over heating and fires in A/C wiring? |
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I think you missed part of what dgbeatty tried to point out.
Because both fans are tied to the same relay output for speed 4 their wiring is shared rather than isolated.
While that connection bridge is intended for use by speed 4 it is there all the time and the other fan speeds can use it too.
This is a design flaw and VW should have used 2 relays or a special relay with 2 isolated output pins.
Mark
| djkeev wrote: |
.......
They become separate at the connection in the D pillar not far from the relays.
Each blower has a 100% separate feed up the D pillar and to each blower/resistor.
The shared load is only for a short distance, inches really, in the D pillar.
Dave |
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32625
Location: Reading Pennsylvania
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| Posted: Sat Jul 10, 2021 3:42 pm Post subject: Re: Overheating and fires in A/C wiring? |
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I looked closely at my Fan wiring.
They absolutely run two separate wire harnesses from the D pillar by the relays into the Evaporator housing.
You can see how they go to individual harnesses.......
Even the ground wire is proprietary for each fan motor.....
Here are the wires on one of the resistors
There is this in harness junction of green wires but it serves the one fan....
The High speed Black wire has a similar in harness connection.
I really don't see the wiring to each fan motor as being problematic.
I stripped the outer sheath off because it was exterior fire damaged, not internal overheated wire damaged.
I'm focusing on the relay being under sized. As Kam pointed out the new substitution relays are specified have a heavier duty rating.
Dave
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dgbeatty
Samba Member
Joined: October 26, 2006
Posts: 702
Location: Sacramento
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| Posted: Sat Jul 10, 2021 5:17 pm Post subject: Re: Overheating and fires in A/C wiring? |
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Great pictures Dave. The connector where the two fan harnesses seperate is a problem area with the 6.3mm terminals carrying 40amps, in each direction of course, for a total of 80 amps 2 x 40 ~520 watts, more than the radiator fan at speed 3 and yes the amperage is counted twice. The design called for four terminals instead of two. VW didn't even use the larger 9mm terminals. That is a lot of current on medium size terminals in a small area.
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djkeev
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crazyvwvanman
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Joined: January 28, 2008
Posts: 9935
Location: Orbiting San Diego
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| Posted: Sat Jul 10, 2021 7:10 pm Post subject: Re: Electrical Overheating and fires in A/C wiring? |
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You missed my point. The 2 fan harnesses are tied TOGETHER at the output wiring for the speed 4 relay high current pin at connector T2c/2.
Therefore the fan harnesses are NOT 100% separate, they are joined.
The effect of this junction is that the 2 fan resistor outputs are wired in parallel. If one resistor fails then the other would become the 1-3 speed resistor for BOTH fans, with current flowing in the opposite direction back to connector T2c/2 and then to the other fan motor. I don't think one resistor is up to carrying the current for both fan motors for sustained periods. Who knows.
Mark |
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djkeev
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Joined: September 30, 2007
Posts: 32625
Location: Reading Pennsylvania
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| Posted: Sun Jul 11, 2021 3:12 am Post subject: Re: Electrical Overheating and fires in A/C wiring? |
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| crazyvwvanman wrote: |
You missed my point. The 2 fan harnesses are tied TOGETHER at the output wiring for the speed 4 relay high current pin at connector T2c/2.
Therefore the fan harnesses are NOT 100% separate, they are joined.
The effect of this junction is that the 2 fan resistor outputs are wired in parallel. If one resistor fails then the other would become the 1-3 speed resistor for BOTH fans, with current flowing in the opposite direction back to connector T2c/2 and then to the other fan motor. I don't think one resistor is up to carrying the current for both fan motors for sustained periods. Who knows.
Mark |
I'll admit, I don't fully grasp it ....... but that's ok, there are many things I use that I don't fully grasp how they work!
I sometimes must trust others smarter than I.
Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
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https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
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jimf909 
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Joined: April 03, 2014
Posts: 7468
Location: WA/ID
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| Posted: Sun Jul 11, 2021 6:30 pm Post subject: Re: Over heating and fires in A/C wiring? |
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I love the photo below and reference to the new part #. The 15 amp A/C clutch relay in my van gets really gets hot so I'm going to replace it.
As for buying a replacements, is there any reason to buy the Porsche parts from ECS that are about 10x the cost of others?
Or the $62 orange relay instead of the $5 black box?
https://www.ecstuning.com/b-original-equipment-supplier-parts/a-c-relay/431951253f~oes/
Thanks.
| kamzcab86 wrote: |
As I've mentioned elsewhere, when I had to replace the high-low pressure switch due to an internal freon leak, which leaked into the wires and relays, I discovered VW superceded two of the relays with higher amperage versions (not that this is the source of fires, but it could be a contributing factor as the original relays age/wear).
Part numbers:
Photo of updated relays and such:
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| Abscate wrote: |
Do not get killed, do not kill others.
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Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.
Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro). |
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pdm777
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Joined: August 06, 2012
Posts: 348
Location: Clovis, CA
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| Posted: Sun Jul 11, 2021 6:39 pm Post subject: Re: Electrical Overheating and fires in A/C wiring? |
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I replaced the wimpy stock wire with a FAT
wire from the alternator to the AC panel (see photo below).
Clean the grounds and all connections.
There were signs of the wire/connection getting Way Too Hot.
Then, I 'upped' the voltage from the alternator
using an adjustable voltage regulator.
https://www.prancingmoose.com/AdjustableVoltage.html
Set the Voltage to 14.7V (perfect for AGM charging)
at the battery. with all accessories off.
Everything runs better with an extra volt.
Faster running AC fans, better cooling, better engine response.
Others have noted similar improvements with voltage increase.
A 1.5V increase makes a dramatic improvement.
Note: when running the AC fans on 'HIGH"
and the big 350W radiator fan kicking in, the voltage
of a stock system (alt charging at 13.5V - 13.7V)
will drop dramatically, as low as 12.4V (too low).
Those fans suck A Lot of Juice!
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djkeev
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Joined: September 30, 2007
Posts: 32625
Location: Reading Pennsylvania
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djkeev
Samba Moderator
Joined: September 30, 2007
Posts: 32625
Location: Reading Pennsylvania
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| Posted: Sun Jul 18, 2021 4:53 am Post subject: Re: Electrical Overheating and fires in A/C wiring? |
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As I reassemble and repair my burned D Pillar A/C wiring in my 90 Tintop
I discovered something odd.
Besides the Bentley Fan control wire colors being incorrect........ 
My fan speeds were wonky.
Speed 1 position gave me a Medium High speed
Speed 2 position game me High speed
Speed 3 position gave me a low speed
Speed 4 position also gave me a low speed
I've already diagnosed this problem to the Fan Speed Switch by pulling the switch and unplugging the harness from the switch.
When I jump the Black 12v + wire to each of the various speed points, I do indeed get the proper Fan Speeds.
Slow
Medium Slow
Medium High
High
I wonder, if the fan switch is feeding the wrong speeds at a given setting, could this "excess" of electricity in spots where it shouldn't be cause the High Speed relay fire?
I've yet to do any post mortem testing of the switch but I suspect power coming out of all sorts of terminals that it shouldn't be coming out of as problematic.
To me, this mixed up fan speed delivery is a smoking gun in the Diagnosis game.
Dave
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http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
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Abscate
Samba Member
Joined: October 05, 2014
Posts: 22668
Location: NYC/Upstate/ROW
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| Posted: Sun Jul 18, 2021 1:08 pm Post subject: Re: Electrical Overheating and fires in A/C wiring? |
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The electrical who designed that, the department who approved it, right up to the head of VW should get whupped upside the head and thrown into the TDI. crusher for cobbling together that crap.
Trabants have better electrical than that, and they use vacuum for everything
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djkeev
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