zx td 94 cooling fans not working (twin cooling fans)

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8304
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zx td 94 cooling fans not working (twin cooling fans)

Post by 8304 »

hello people,

i have the above problem....

my engine got to 100 deg c. wityh no sign of the cooling fans starting and to be honest i dont think ive ever seen them running....

what temperature are they meant to start at?? i assume its less than 100..

what are the components which control the fans, i have seen three different temp probes comming out of the head on the engine but which one is likly to be at fault??

any ideas....?

also are the fans meant to come on at the same temp as a non turbo diesel zx??

cheers
alastair
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Post by Clogzz »

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fanzzz

Post by 8304 »

thanks clogzz,

one observation though, my car doesnt have the brown sensor which is mentioned instead just a blanking plug.

My car has:

*a unit threaded into the radiator with three pin connector going onto it - which i replaced earlier but still no change...

*a unit threaded in behind the fuel filter with only one pin and a connector on it - maybe the warning light switch??

*temperature gauge sensor threaded infront of the fuel filter.

*cluster of three relays between the cooling fans.



is there any way of testing the fans in situe to see if the brushes have gone etc??

any other ideas??

cheers
Zxtd Aura converted from 1.8i Petrol - Lowered, 20psi boost extra fuel - weeeeeee!

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Post by JohnT »

I hope this helps....lifted from a previous post on the subject. I seem to remember that is one fan does not work then they both will not work!
Here is the info on stripping them down if you fid a positive feed to the fan motor......
and here's the answer: (compliments of Alan S.)
Well, what do you know, we got it apart; took about 15 minutes.
The fans ends are held together with the metal from the stator cover (for the want of a better term) pushed through small rectangular slots in about a half a dozen spots on both the front and the rear of the fan motor. They look like a 3 pointed crown in cross section as though a slot of metal has been hit in two spots by a sharp cold chisel.
Setting a punch in the vise after it had its face squared off on the emery wheel, just sit the edge of the splayed out section that pokes through the slot on the punch and with a second, smaller punch, tap from the other side of the slot so as to tap the splayed out part down. Turn it over and do the other side.
When all have been done, tap the lugs through the end plate and repeat the dose at the other end.
The carbon brushes are fitted to a fibre mounting plate at the end and have 4 brushes each 6mm X 8mm and approx 18mm long. Cut the pigtails on the old brushes about 5mm from the brush and solder the pigtails of the new brushes to them; you'll never uncrimp and recrimp the fittings on the originals.
When getting replacements, it's necessary to get the ones with the high copper content rather than the high carbon and the pigtail on the originals comes out the end but some of the replacements have it coming out of the side at the top; in this case due to the way the brush holders are constructed, this is not a problem.
Bearings would be cheap & simple to fit.
My car had supposedly had a secondhand one fitted prior to my purchase & the previous owner charged A$265. The carbon brushes were A$10.50 a pair so for $21 plus a set of bearings, I will have what is effectively a fully reconditioned fan motor. We'll skim the armature just for the hell of it, but at the end of the day, well worth the effort.
Alan S
Cheers!
John
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Post by 8304 »

cheers john and clogzz,

it looks to me like it might well be the brushes in one of the motors preventing both of them from working (as they start in series)

is it possible to remove the fan motors in situe??
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Post by Clogzz »

Sorry, should have looked properly and realised that you're talking ZX, while I was thinking Xantia, where it's different. :oops:
Since the thermoswitch is new, the fault must be in the 3 relays behind the grill, or their connectors, or as per above post, a faulty fan.
Shorting the thermoswitch wires to ground as explained in this thread, particularly Tom's post, should give you an idea of where the fault is:

http://www.bxclub.co.uk/forum/viewtopic.php?t=908

Also ensure that the thermostat isn't stuck shut, preventing the warm water from reaching the thermoswitch.
Last edited by Clogzz on 12 Feb 2006, 11:49, edited 1 time in total.
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zx fans

Post by 8304 »

no problem clogzz thanks for your help anyway...

although i have changed the rad switch i still suspect it as it was not new, this is why:

i took the plug off the back of the thermo switch and checked to see if there was 1 live pin in there somwhere, there was and the others had no charge. I then switched ignition on and connected a piece of wire between the live pin and the other two pins and both fans ran, using different combinations of pins the fans will run at the low and high speed.

I want to buy a new thermo switch for the radiator as i think this will cure the problem.

I have read about being able to get a thermostat which operates at a lower temeperature, when people mention this do they actually mean the thermo switch?? as i would like to get one which operates at say 85 deg C

cheers

alastair
Zxtd Aura converted from 1.8i Petrol - Lowered, 20psi boost extra fuel - weeeeeee!

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bx post

Post by 8304 »

hi again,

my car behaves exactly as described in the bx post above so i think it must be the switch.

maybe because both of the switched i have tried are old they are comming on at a too high a temperature.


My main question is ive heard of an upgrade where the switch can be purchased to operate at a lower temperature - has anybody heard of this?????

cheers

alastair
Zxtd Aura converted from 1.8i Petrol - Lowered, 20psi boost extra fuel - weeeeeee!

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Post by Clogzz »

Since you get both fan speeds when shorting the thermoswitch terminals, everything is normal in that area, and with 3 pins and one live, it is indeed shorting them together that turns on the fans, and not shorting them to ground as I posted, this being for 1 and 2-pin switches with no live wire.

The thermostat proper, the one letting the water through to the radiator, was originally 92ºC, and is replaced by an 82ºC thermostat, at least on the Xantia, that I know of.

The thermoswitch on the radiator also comes in several switching temperatures, but no idea as to what they are.
Thermoswitches, and thermostats too, deteriorate over time, and only new ones can be trusted to be good for a long time.


Addition at 12.23 PM GMT:

Last post was being written before I saw your last one.
Try reading the temperatures on the old switches, and maybe get one lower.
A thermostat with lower temperature will also help.
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Post by James.UK »

The fans on a ZX run very quietly! I had never heard my fans running untill I wanted to check everything under the bonnet was ok with the engine running, I was very surprised to find that both fans were working when I looked..

I could not hear them from inside the car with the engine turning over.. :oops: :roll:
James. (Nr M67 East of Manchester).
Dark Blue ZX 1.9D Auto 1994 'L' 5 dr (modified) Aura. 98K miles used daily. Ave mpg 40
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Post by jeremy »

In 1994 haynes stated that ZX TD had a thermostat that started opening at 83 degrees and was fully open at 95 degrees. Without air conditioning the fans should cut in (1st speed) 90.5 - 94.5, second speed 95.5 to 99.5

Cut out speed is 85.5 to 89.5 and second speed 90.5 to 94.5.

the speeds for a Td with air con are different but I think this is because a different control is used (Bitron on cylinder head?) I have not checked this and will quote the aircon temps if required.

I have a ZX 1.9D with twin fans! - and a towbar which probably explains why - and can confirm that the fans are very quiet! From the way my TD BX works I'd say that if the temp ever got near 100 I'd flush the rad and check it. (Both never show any temp unless standing with the engine running for a VERY long time.)

jeremy
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zx radiator switch

Post by 8304 »

hi guys

just to let you know the outcome of this thread:

i changed the fan switch in the radiator and all is now well, the fans start just above 90 and the engine is down into the 80's when they stop - i havnt chaecked that the second stage works becuase the engine never gets hot enough now but im the fast speed will work.....

it cost £18 though, bit steep i though.....

cheers


alastair
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Post by Clogzz »

Always nice to read about a good outcome. :D
As for £18 for the part, I think that the simplistic Imagereasoning is that 3-pin switches have to be more expensive than the 1- and 2-pin switches. Image
They may charge £6 per pin. :evil:
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Post by oldnail »

Should have gone to GSF.I have just replaced mine,£8 plus vat.
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Post by James.UK »

Hi jeremy..

>>I have a ZX 1.9D with twin fans! - and a towbar which probably explains why<<

Come to think of it, I have never seen a ZX 1.9D with only one fan? :? Do they make them?? :roll: :)
James. (Nr M67 East of Manchester).
Dark Blue ZX 1.9D Auto 1994 'L' 5 dr (modified) Aura. 98K miles used daily. Ave mpg 40
Wedgewood Blue 75 CTD auto Connoissaur. 2002. 144k. used daily. ave mpg 40 ish.
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