RAD FAN not working!!

[nickthe fish]

Hi All,

I have been suspecting that my rad fan doesn’t kick in when the temp gets hot so I decided to test it before I find out it do4esnt work whilst I’m on the M25.

It’s a 1.9 1983 Water cooled wedge, I had an issue last year where the temp gauge shot right up and replaced the heat sensor which resolved the issue, but now the needle sits at ¾ rather than ½ way as it used to not such a big problem, and I have always had the phantom flashing light on the temp gauge that seems to plague allot of Wedges.

Night before last I raised the engine temp as high as I dare and no fan kicked in, after reading the wiki I tested the plug on the fan using a paper clip and the high fan kicks in but not the low fan,

Has anyone any thoughts on if I should,

A. Replace the thermo switch?
B. Replace the thermostat?
C. Replace the fan?
D. Hardwire the high fan to the low on or always in the on position to be on the safe side? (I have concerns about having it permanently on)
E. All of the above?
F. Give up and take it to the garage and let someone else sort it out.

Any advice would be gratefully received.

[kevtherev]

hello and welcome
A. Replace the thermo switch

three pin is it?

[nickthe fish]

Yeah its 3 pin,

So i guess if the thermo switch doesnt do it, then replace the thermostat???

Acccording to the 80-90 wiki it suggests that the fan is for the knackers yard if only one of the fan settings comes on. i.e high no low or visa versa.

If one of the pins works and the other doesn't, does this not effectivley overide the thermo switch? therfore thermo switch not at fault?

[VERAT25]

hi.
had this very same problem/ replaced thermostat/ bleed system etc etc.............all ok now/ engine runs with temp gauge in center/ if it rises above that 3/4 fan kicks in

verat25(cardiff)

[nickthe fish]

NIce one vera,

Did you bleed the whole system as part of a service? or was it part of the fault?

Was the fault with the fan not kicking in with the thermostat?

Not sure what to make of the fan not working on low but working on high? I am happy if at least it works on high setting.

[kevtherev]

OK I would rewire the low fan spade from the high, just to see if it works..
before that I would be testing for connectivity

taking the fan out is a big job

the low speed fan rarely comes on in mine during normal operation... and I have lower temp settings on the switch and thermostat.
If the guage is correct then its telling you there a flow problem, red light flashing intermittent is a conection issue

[nickthe fish]

Thanks Kev,

I am not the best with electrics, i can figure out the re-wire, but in regards to what you mean by connectivity can you expand a little on this please? What do you mean and how do I do it?

The gauge only shows at 3/4 since I put a new temp sensor on, I am guessing its the wrong one as the colour band around the sensor was different to the original. so i don’t think there is a flow problem.

As for the flashing light, this is totally intermittent so it’s not really a issue, reading the forums it’s a common T25 issue.

How did you get lower temp settings on the switch and thermostat?

[kevtherev]

connectivity..
check that the connectors are connected (clean them up!)

which includes the header tank switch that's flashing now and again..it may need a clean inside and out.

so you didn't mention the temp sensor, I fitted the wrong one and this happend to me also.
Try to remember what you have already done, as it helps with advice

As for the lower temp thermostat and switch,
Any good GSF will supply a lower temp thermostat, mine opens at 83 deg instead of 87, and the thermo fan switch comes on low speed at 89 deg and full chat at 96 instead of 98 (?) and 103 deg

All this is to keep the oil cooler, which keeps oil pressure up at lower rpm

[matt brighton]

Hope you dont mind me joining in with a related question.......

I have a 1.6d (non turbo) 1982 devon. It seems to run cool but i too dont want to find a problem when I need the fan to operate properly so I did the suggested testing

I have searched threads as recomended before asking questions and liiked on wiki but would really appreciate if anyone can advise on what I have found....

It has x2 thermo switches in the rad - the top one (stage 1 ?) has 3 pins - all wired up to the loom - a 12v live feed is on one of the outer pins - and by bridging the outer 2 connections the fan starts. Good !

The lower thermo switch has just x2 pins and I found no wires connected - the loom has an unconnected live 12v feed spade connection hanging loose which must go to one of the pins ?.

Wher should I find the missing wire - or wher does the pin on the lower themo switch connect to ?

Is a peace of mind fix to hard wire both to a 2 stage toggle switch on the dash and manually activate the fan .

Any observations very welcome

Matt - brighton

[nickthe fish]

Hi Matt,

I cant help you i'm afraid bit of a novice myself, not sure about the two thermo switches? sound odd I thought the at the top right should be the thermostat and the bottom the thermo switch, but yours is a couple of years older than mine.

I swapped round the high fan for the low fan last night and run the engine as hot as I would dare go and it still wouldn’t kick in, my plan is to run a wire from the high fan and the live pin into the cab and put a switch on so I can manually activate the fan if I am sitting in traffic, bit archaic I know but if I need a new fan I have been told that its £150-£200 in exchange for a £3 switch I know which route I am going to take.

Does any one know if i have to use wire and a switch with a rating??? as I think the fan is 200-300watts and not sure if i need a sturdy cable/switch. Or if there is any advice anyone can give about this? i.e best place to run the cable into the cab? as stated before electrics not really my thing

[matt brighton]

Thanks Kev

Im still in very early stages of understanding vw and enjoying soaking up the plentiful info/advice on offer, as well as the friendly and helpful scene that goes with vw's too. As a newbie I dont feel qualified yet to offer advice unless im sure its right.

P 19.5 in the section of the downloads detailing cooling system show the 2 thermoswitch units for my camper (1982 t25 1.6d non turbo 4spd manual).

I have had alot of experience with Rover 75 "fans" - the cars and enthusiasts (pl dont ask why ) and the end of a long story is that kenlow can do an affordable off the shelf option for that car as op[osed to OEM £400+ ish prices for supply of the unit only. I ended up splicing a new replacement motor into the speed control set up for the Rover as it required 3 speeds to be available and only available units are later 2 speed. Sorry - I digress....

Some fan motors can be repaired relatively easily if you can go to the bother of sourcing the parts that wear (brushes springs etc etc as individual items - a bit like the diy kits for alternator rebuilds

If the fan itself is working then the brushes etc inside must be ok - then you go back to resistor packs etc and speed controls - not something I am knowledgable enough on vw's yet to confidently offer you advice on.

I personally like the idea of being in control of when the fan is on or off with a . I have "fried" enough cars with fragile alloy heads ( notably my dads beautiful black 528i BMW in the summer of 1984 - he still bears a grudge) to have a 6th sense.

May need a relay to cope with the current when wiring in a dash switch

Hopefully one of the sages here will be along to tell us if its possable and how - must have been done before ?

Regards

Matt - brighton

[nickthe fish]

Fan is now kicking in after changing thermo switch, low fan is still not working but due the re-wire the high fan comes in at the lower temp, thanks all for the advice