Radiator fan and Fusebox questions.

[davegsm82]

I realised the other day that I've never heard my radiator fan and thought I'd investigate.

Looking at the wiring diagrams from Syncroandy's website I saw that relay 5 is the high speed relay but that position is empty in my bus. I bridged the N/O and COM contacts and there was no fan.

I went to the radiator however and pulled the plug on the thermoswitch, bridging the low and high speed contacts made the fan run at the right speeds.

So, I'm curious, where is my max fan relay? and what would be the best way to make sure the thermoswitch is cutting in? Just leave it idling after a run and see if it clicks in?

Also, I noted that I only have 3 relays in the fuse box;
8 - X-contact relief relay (18)
10 - Intermittent wash wipe (229) Added by me
12 - Emergency flasher/trailer relay (22).

I have removed relay 3 - Coolant shortage control unit (43) because the clocks now handle the coolant low function directly.

All of the other relays aren't present and I'm curious what their original functions would have been, they aren't listed on the wiring diagram. Numbers 1,2,4,6 and 9.

[dave friday]

on my van the first stage fan only comes on after 25 minutes up hill at low speeds [after I stop ].
what engine was originally fitted?

[CovKid]

Ah, I answered this t'other day for someone whose high speed kept blowing a fuse. I think its in same place on all models - right above the earth crowns. Either relay has failed or more commonly, connectors on it are all furred up.

[Oldiebut goodie]

[CovKid]

Unfortunately they do tend to get as crusty as the earth crowns over time. Sometimes re-seating it will do the trick.

[ZsZ]

This is the relay for the 500W blower motor installed only on turbodiesel JX and petrol DJ AFAIK

The fuse can crack as it does in the glow plug circuit, and the positive wire often overheats. Beside that the fans 6mm2 ground wire is attached to the earth crown through a 6,3mm spade connector which is barely enough especially when corroded a bit. So it is also overheats but more often.
circuit diagram:
http://i31.tinypic.com/24wrbf8.jpg" onclick="window.open(this.href);return false;

[davegsm82]

Thank you for the replies, yes that all makes sense, I didn't check that far up above the fuse box so I never saw it.

The bus originally had a JX but I chopped it out for an AFN. I just wanted to make sure that the rad fan system was working fine which it appears to be.

Dave.

[CovKid]

That relay and its associated wiring can be a menace, as ZsZ says. Mine kept blowing fuses until I dug around in there and cleaned everything up. I've said it many times in threads, and even covered it in the WIKI, that the power supply up to the dash was barely adequate even before we all started adding items to the dashboard. VW were very mean in this respect. It all has a knock-on effect with poor headlight output and the potential for dash fires.

To be fair, the problems is largely the result of age, or at least time, and moisture. There is little left on my wiring loom that I haven't replaced or upgraded in recent years. Even the earth crown was replaced with a bus bar over the summer as I was forever having to clean the spade connectors.

More recently I dumped those dreadful blower motor resistors too, replacing them with a modern PWM motor controller:
https://www.youtube.com/watch?v=3GzJ8N1Rqp8" onclick="window.open(this.href);return false;
https://www.youtube.com/watch?v=3S24Hty4_bs" onclick="window.open(this.href);return false;

At some point, when I fit my new radiator, I'll rewire the fan loom and install a more sensitive temperature probe to improve fan response. Still musing that one.....

Possibly something like: http://www.ebay.co.uk/itm/Adjustable-Fa ... SwnNBXUX5X" onclick="window.open(this.href);return false;

[davegsm82]

I think when I get time I will add some better cabling to the front of the bus, I have some lengths of 16mm2 cable from the machines I work on (linear accelerators) which will do the trick perfectly, just need to make a good splice point at the front in the fusebox.

As for the crowns, yea I intend to do something about those, I never liked the design of them as it is.

With regards to the PWM controller for the main fan, I personally think the fan is rubbish as it is and perhaps this is attributed to the volt-drop from front to back. I repaired my resistors by twisting the broken ends of the Nichrome wire together where it had fractured but it's gone again. I've got big plans for the future involving servo's, PIC's and displays A-la climatronic, but for now I'm going to fit a PWM controller similar to what you have done but with the exception that mine will plug in between the plug and socket of the existing control and require no modification. Just need to add some 'energy recovery' to protect the controller then it should be working fine.

Dave.