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JEL91Westy
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Location: Central PA
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 Posted: Tue Jan 31, 2023 5:43 pm Post subject: 1990 radiator fan not working SOLVED |
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I have looked through many of the posts, consulted the Bentley, and did some testing, but I can’t figure this out. Just reinstalled rebuilt motor, and am troubleshooting high gauge readings that I think are the sending unit calibration, my light has flashed but no fan. I hit the fan switch with the IR and only had 180 on the threaded brass section. So instead of running up to that temp considering I could still have some air pockets motor I tried jumping the plug at the fan switch, but I still can’t get it to run. So with it jumped per the below circuit diagram, I tested across the terminals on the fan and have nothing. I have 12V at the plug - RW wire to ground. The diagram doesn’t show anything between the switch plug and fan on the R/BK wire, so what is going on?
Also I thought the fan always came on when the AC was on, but that doesn’t seem to happen either, and I can’t find the AC circuit diagram.
Thanks for any insight.
Joe
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djkeev
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JEL91Westy
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Joined: December 04, 2020
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Location: Central PA
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| Posted: Tue Jan 31, 2023 8:30 pm Post subject: Re: 1990 radiator fan |
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Thanks for the response. Sorry if I was’t clear, I have 12v at the plug to the fan switch, but I don’t have voltage at the fan when I jump R/W and R/BK, which based on my read of the diagram should give me 12v at the fan.
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DuncanS
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| Posted: Tue Jan 31, 2023 9:09 pm Post subject: Re: 1990 radiator fan |
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What happens when you run a special wire directly from the battery to the fan? Do you have cleaned grounds?
| JEL91Westy wrote: |
| - RW wire to ground.Joe |
The Red/White wire does NOT go to ground. It feeds the fan through the thermostat switch, changing then to Red/Black.
ONLY BROWN wires go to ground.
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JEL91Westy
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Location: Central PA
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| Posted: Tue Jan 31, 2023 9:32 pm Post subject: Re: 1990 radiator fan |
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I meant when I take R/W to ground at the plug I have 12V but then jumping that to R/BK at the plug I am getting nothing between the hot and ground at the fan.
I will try jumping 12v directly to the fan, but again I don’t see anything between the plug and the fan interrupting the hot R/BK other than a connector. It isn’t adding up.
And am I correct that when the AC is turned on the fan should come on?
Thanks.
Joe
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chrissev2
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Joined: March 03, 2012
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Location: Toronto
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| Posted: Tue Jan 31, 2023 9:43 pm Post subject: Re: 1990 radiator fan |
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Two things it could be:
1. Did you check the resistor behind the driver's side headlight? Usually it will be a rusty, non functional mess.
2. Same for the ground tree to the left of the driver's side dash, underneath. Usually a rusty mess. The fan ground is on that.
There is also a relay somewhere, though I forget where now. I fixed my high and low speed fan years' ago and found that the above problems were causing issues, among other things.
With a Vanagon, usually it is a "cluster" type of problem. It is an antique vehicle whose electrical system was poorly designed to start with. You have to be a bit of a detective. Leave no stone unturned.
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crazyvwvanman
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| Posted: Wed Feb 01, 2023 4:19 am Post subject: Re: 1990 radiator fan |
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Look at Bentley Page 97.53 for an index to where to find various diagrams.
The 86+ A/C wiring isn't just an add-on, it is embedded in the radiator fan wiring.
You need the A/C diagram to understand what is going on with the fan wiring.
(note:a few colors are wrong the the rad fan wiring in the A/C diagram)
Mark
| JEL91Westy wrote: |
... I can’t find the AC circuit diagram.....
Joe |
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djkeev
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djkeev
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JEL91Westy
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| Posted: Wed Feb 01, 2023 4:56 pm Post subject: Re: 1990 radiator fan |
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Yikes, those diagrams just got a lot more complicated! I wasn’t finding this section for some reason. Scary part is I have notes I made on this page that are probably from 20 yrs ago, so I have been here before.
What does F18 on track 31 at the radiator thermoswitch mean, or S42 on track 33 at the cooling fan fuse? I don’t see those on the how to read page.
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djkeev
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crazyvwvanman
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| Posted: Wed Feb 01, 2023 5:17 pm Post subject: Re: 1990 radiator fan |
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Those are just an additional component identifier added to later wiring diagrams.
Mark
| JEL91Westy wrote: |
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What does F18 on track 31 at the radiator thermoswitch mean, or S42 on track 33 at the cooling fan fuse? I don’t see those on the how to read page. |
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JEL91Westy
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| Posted: Wed Feb 01, 2023 5:23 pm Post subject: Re: 1990 radiator fan |
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I understand that, but what does “F18” actually indicate?
The fan works when I jump from the battery.
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DuncanS
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| Posted: Wed Feb 01, 2023 5:50 pm Post subject: Re: 1990 radiator fan |
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Since the fan works with a direct feed, you now need to start going upstream to find out where the juice is being blocked. Touch a battery positive lead to red/black wire terminals marked 4/85 on current path 31. Do you hear a click as the relay is triggered and does the fan run? If nothing, then touch the positive battery wire to pin 8/87 on the relay, current path 33. if the fan runs, the relay is bad. If the fan doesn't run the wire or its terminals are bad. And so on. Have you checked all the fuses? For continuity across the terminals? The fuse may be good, but corrosion may be blocking the current flow.
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MarkWard
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| Posted: Wed Feb 01, 2023 5:57 pm Post subject: Re: 1990 radiator fan |
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| JEL91Westy wrote: |
I understand that, but what does “F18” actually indicate?
The fan works when I jump from the battery. |
F18 is just a component identifier. There is a table in the diagram that lists the components and their identifier so you can locate them in the diagrams.
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JEL91Westy
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| Posted: Wed Feb 01, 2023 6:00 pm Post subject: Re: 1990 radiator fan |
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I apologize for my ignorance, but where is that relay - J135. I don’t see it at the fuse panel
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djkeev
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Howesight
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| Posted: Wed Feb 01, 2023 6:30 pm Post subject: Re: 1990 radiator fan |
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| JEL91Westy wrote: |
| I apologize for my ignorance, but where is that relay - J135. I don’t see it at the fuse panel |
In my 1986 Syncro, the main rad fan 50 amp fusible link is behind the dash, above the fuse panel. You can unscrew the fuse panel and move it to gain access and sight to that fusible link to ascertain whether it is blown.
In the top left of the picture below, the "highest speed" rad fan relay is seen. This is the one called "J135" which you have asked about. On my relay panel, you will see two relays that I added to install my DIY A/C system. There is also a relay marked "rad fan med" that came originally from the factory.
The point of showing you where the relays are is to allow you to replace them if that turns out to be necessary.
(open pic and expand for a better view)
If your rig has factory AC, then there will also be a harness in the rear "D" pillar depicted in the pic below:
The "D" pillar harness also has a fusible link, but that is only for the large electrical draws made by the evaporator fans.
There is interplay between the factory AC and the rad fan, in addition to the thermoswitch on the radiator. If the AC is switched on (and the outside ambient temp is warm enough), then the rad fan is switched on to its lowest speed. This is achieved by the AC relay supplying power to the two-part "N39" series resistor which consists of 2 separate resistors combined into one part. When electricity flows through both resistors, the lowest rad fan speed occurs. When electricity flows through only one of the two resistors, then the "medium" fan speed is engaged.
For the highest rad fan speed, full power goes through relay J-135 to provide full battery voltage (around 13.5 volts engine running) to the rad fan.
These relays are controlled by the AC system and by the rad fan thermo-switches. That is why the wiring diagram can be confusing.
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Howesight
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| Posted: Wed Feb 01, 2023 7:06 pm Post subject: Re: 1990 radiator fan |
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To narrow down the diagnosing, note that only so many things can cause the rad fan not to function. From my experience and recollection of others posting on the Samba, here are the things most likely to cause the problem:
1. Rad fan switch not operating properly. You can bench test it in hot and boiling water with a continuity test using your volt-ohm-meter (VOM);
2. Series resistor failed: They do fail after 33 years - - mine did. Remove upper grille to access. It lives in the space seen in the pic below. My wiring is bespoke, so don't use my wiring to this resistor as a guide.
3. Relay J135 failed; again, remove it to bench test. Gain access by dropping the fuse panel down and removing the left ventilation grill to see what you are doing.
4. Fusible link blown;
5. Don't worry about your AC system - - it will not cause a rad fan circuit failure.
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djkeev
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