vt cooling fan

[tk55]

hi, have a question to the operation of the cooling fan in relation to the air-con. i remember telling my wife in the past that it's better off having the air-con on when you're caught in a traffice jam because the fan will kick in and running all the time irrespective of the engine temp. this will help in preventing the car overheating. i knew this because i've seen it with my own eye, either with my vt or one of the cars i had owned before.

however, i'd notived recently that my vt is not doing that when i had overheating problem with it. the fan only kicks in when the temp gets up to just over the half way mark, irrespectively whether the air-con is on or not. just wondering if this feature been somehow buggered after numerous repairs i had with the car. the compressor been replaced last year.

is this normal for a 98 vt berlina?

[accentstencil]

The fans should always start when the A/C is switched on. Is your air con working?

[tk55]

thanks for the reply. the air con is working.

i've just read in the other thread where the op mentioned something about hi and low fan relays. could my low fan relay not working? when the fan finally kicks in when the temp hits over the halfway mark be the hi speed? when should the low or hi speed fan comes on?

[accentstencil]

When the air con is switched on both fans should come on at low speed and if the coolant temperature is above 104 degrees then they will both operate at high speed. I would try replacing your low speed fan relay.

[w8stedYouth]

I have the same problem atm(Except my air-con doesnt work... I have changed both high and low fan relays. Fans wont come on(watched my temp get to 94) So now I have to change the thermostat!!
I thought I should add this as this could well be your next step. If it is then after installing the thermostat a radiator flush is needed. I hope its only your relay to save you an hour or so, good luck

ACCENTSTENCIL: Should I let my temp get to 100 or 104 and see if the thermos kick in or just change the thermostat as I will be anyways?

[accentstencil]

Yes, I would let it get to104 degrees and see if they come on. If not, according to my manual you should check fuse number 14 in the interior fuse panel and the fusible links in the engine fuse and relay compartment. Also check the fusible links in the little black box adjacent to the radiator.

[tk55]

ok, just went to look at the relays and realised that the low speed fan relay has been changed before when i had the "fan won't stop even engine is switched off" problem. now i wonder if the new relay has ever been working at all!!! that probably one of the reason why my car easily overheated.....

i know that's a new relay because it's the new tyco type relay which is white in colour instead of black

i'll go and get another relay tomorrow. fingers crossed.

w8stedYouth, the high speed only comes on after 104 deg. the last time i had the diagnostic mode on i remember my fan kicks in when it gets to about 107 deg. could just be a delay action as well as the temp was on the continuous rise.

[tk55]

accentstencil, just check those fuses as you suggested. perhaps berlina is different but fuse 14 says "engine cont. bcm"? and couldn't find any fuse in the engine compartment that say cooling fan at all. the little box next to the radiator has 2 fuses and they look ok (without checking with a multimeter).

according to your manual, what are the fuses called?

btw can i unplug any fuse to check for continuity? would it stuff up anything if current is cut from some equipment especailly the computer?

[accentstencil]

I checked my fuse 14 before I wrote that and it says the same as yours but that is definitely what the manual said. There should be a fusible link in the engine compartment fuse panel for the fans.
Unplugging any of the fuses won't be a problem, it's just like disconnecting the battery, but you might need your radio PIN

[tk55]

bought the low speed relay this morning. also checked the fuse 14 as well as the engine cont. fuse (10A) in the engine relay and fuse compartment to be ok. those big fuses with see-through top (fuseable link? 60A each) would not come off. the one that says engine F/L make a spark when i tried to pull it. got scared and stopped

anyway, still the same situation, except while i was looking around with the engine and air-con running the fan suddenly came on!!! ran for a couple of seconds then turned off. came on again about half to a minute later, again for 2 seconds.

hmmm.....checked the temp gauge and it's at normal, half way between quarter and half way mark. so it's not the high speed at 104 deg obviously, which would be just over the half way mark.

so what's the story? perhaps this is normal for this car? btw my car is no longer overheating. that was caused by the radiator which has already been replaced. no more losing water either.

can you vt berlina owners out there verify this for me? turn on the engine and put the air-con on. does the 2 fans come on straight away, or not?

[11gothevt11]

bought the low speed relay this morning. also checked the fuse 14 as well as the engine cont. fuse (10A) in the engine relay and fuse compartment to be ok. those big fuses with see-through top (fuseable link? 60A each) would not come off. the one that says engine F/L make a spark when i tried to pull it. got scared and stopped

anyway, still the same situation, except while i was looking around with the engine and air-con running the fan suddenly came on!!! ran for a couple of seconds then turned off. came on again about half to a minute later, again for 2 seconds.

hmmm.....checked the temp gauge and it's at normal, half way between quarter and half way mark. so it's not the high speed at 104 deg obviously, which would be just over the half way mark.

so what's the story? perhaps this is normal for this car? btw my car is no longer overheating. that was caused by the radiator which has already been replaced. no more losing water either.

can you vt berlina owners out there verify this for me? turn on the engine and put the air-con on. does the 2 fans come on straight away, or not?

Hi there
Do you have a thermosat installed????
The reson i ask as i currently don't have thermosat..
(yes i know this is not good for engine)
But i will be installing one on weekend...
Still reading between 1/4 and 1/2 way mark???
Yes when air con comes on thermofans always turn on straight away
Thanks

[tk55]

thanks 11gothevt11. yes i still have thermostat. asked my mechannic twice in the past about removing it and he was strongly against it. reason given was "there's a reason they put it in there in the first place"

my theory is that it was there for only one reason: to ensure the engine gets to the manufacturer's recommended optimal temp as quickly as possible. i'm quite sure the engine still get over 89deg even without the thermostat, except taking longer. since yours does not have thermostat, you could tell us if that is true?

anyway looks like i need to investigate further regarding the thermo fans

[11gothevt11]

thanks 11gothevt11. yes i still have thermostat. asked my mechannic twice in the past about removing it and he was strongly against it. reason given was "there's a reason they put it in there in the first place"

my theory is that it was there for only one reason: to ensure the engine gets to the manufacturer's recommended optimal temp as quickly as possible. i'm quite sure the engine still get over 89deg even without the thermostat, except taking longer. since yours does not have thermostat, you could tell us if that is true?

anyway looks like i need to investigate further regarding the thermo fans

Yes this is true....I don't have thermosat in my car for the last 18 months..........
Since i'm a member of jc i read heaps on thermosats......
And i decided to buy one today low tem opening 82 .....But with no thermosat engine did overheat only twice in 6 months 3/4 on tem gauge...I have bleed all the air out ....But when i fill it right up to just under the overflow pipe...
In morning it needs a little top up around 100ml....
So I have got tiny leak iam looking for???
Yes engine would normaly sit around 86-89 degrees.....Just takes longer to get to that tem........
Thankyou

[11gothevt11]

thanks 11gothevt11. yes i still have thermostat. asked my mechannic twice in the past about removing it and he was strongly against it. reason given was "there's a reason they put it in there in the first place"

my theory is that it was there for only one reason: to ensure the engine gets to the manufacturer's recommended optimal temp as quickly as possible. i'm quite sure the engine still get over 89deg even without the thermostat, except taking longer. since yours does not have thermostat, you could tell us if that is true?

anyway looks like i need to investigate further regarding the thermo fans

Did you get standerd thermosat???? 92 degrees????
Spare parts guy said its 92 degrees ...???

[tk55]

it's standard thermostat. i just thought i read somewhere it's 89deg. if the standard is 92 then it's 92.

i've just gone down to the car to check all the fuses in the engine compartment with a multimeter. all fuses checked out ok except 3 that refused to come off. they are the 2 fan fuses next to the radiator, and one in the main box that say engine f/l. i've pulled pretty hard and the covers moved a bit but the whole fuse won't come out. can somkeone tell me how to get them out? from the top windows they all looked good though.

accentstencil, can you look up your manual and see what else should i check. the fans still won't come on when i start my air-con. they both definately run when the temp hit high.

so right now as it is, when i'm caught in a traffic jam, the temp would suddenly started to rise gradually till above half, fans come on, temp continue to rise a bit more (sometime as high as nearly three quarter) before starting to come back down to normal (between quarter and half). and the cycle repeats. normal cruising the temp is always at normal. won't even hit half.

it's three quarter considered bad enough? would it blows the head gasket?

[drift-it]

wire up a low fan speed relay by-pass switch...that way u decide when it comes on! you could even do the same with the high speed fan...

not the most logical fix but it works.

[Cheap6]

Hi. I've posted on here a few times in the past about how to check thermo fan operation, in here (VT-VX), some in VR-VS (Brett_jj's inop. low speed VS fan) - VS fan operation is basically the same as VT - in the last 6 months or so and some in the how to on fitting a thermo fan switch. It might be worth a search for those.

Some quick randoms:

Early VT switch both fans low then high according to the switch on criteria, late VT- switch on one fan only then both for "low" and "high".

The BCM controls low speed fan switching, the PCM high (or both if the BCM or 5 pin relay fail).

[tk55]

hey, thanks heaps cheap6

i'm still reading but one thread had this to say:

(copy and paste from other thread)

From here, How to fit thermo fan bypass switch post #21, the switch on criteria for VT fans are:

"V6 Low speed:

On, >: 104C
Off, <: 99C
On with ignition off if > 117C
On with A/C pressure > 1550 kPa
Off with A/C pressure < 1170 kPa and speed > 50 km/h

V6 high speed:

On, >: 112C
Off, <: 108C
On with A/C pressure > 2600 kPa
Off with A/C pressure < 2300 kPa"

VT and VS ecotec should be the same or very similar. Seems like normal operation to me.

(end of copy and paste)

so maybe what i thought was the high speed fan could infact be the low speed fan operation!!!??? lol.....

still looking for the thread that shows how to check the thermo fans operation. be back later......

[11gothevt11]

it's standard thermostat. i just thought i read somewhere it's 89deg. if the standard is 92 then it's 92.

i've just gone down to the car to check all the fuses in the engine compartment with a multimeter. all fuses checked out ok except 3 that refused to come off. they are the 2 fan fuses next to the radiator, and one in the main box that say engine f/l. i've pulled pretty hard and the covers moved a bit but the whole fuse won't come out. can somkeone tell me how to get them out? from the top windows they all looked good though.

accentstencil, can you look up your manual and see what else should i check. the fans still won't come on when i start my air-con. they both definately run when the temp hit high.

so right now as it is, when i'm caught in a traffic jam, the temp would suddenly started to rise gradually till above half, fans come on, temp continue to rise a bit more (sometime as high as nearly three quarter) before starting to come back down to normal (between quarter and half). and the cycle repeats. normal cruising the temp is always at normal. won't even hit half.

it's three quarter considered bad enough? would it blows the head gasket?

Hi there
I installed a low opening thermosat today..82 degrees...

If you want to check what tem yours is its ingraved on the thermosat




Also for other memebers reading this

82 degrees thermosat what do you think????????????????????
Could these do long term damage???

Any comments welcome

[tk55]

did some troubleshooting today with a wiring diagram found from another thread, and a multimeter. seems like the low speed relay did activate when the air-con compressor is engaged. but the low speed didn't come on. tried direct shorting of pin 30 of the low speed relay terminal with a wire to ground and still didn't come on.

checked the voltages of the 4 wires going to the thermo fans and found only 3 has the full 12v (yellow, green and blue). the black wire was below 10v! traced the black wire with the multimeter and found it connected to the pin 30 of the low speed relay. so looks like the control circuitry is working properly but the fans are faulty

i don't know how the internal of the fan motors are wired (coiled) for the low and high speed. but is it even likely for both fans' high speed coil to be working but low speed's broken? just find it hard to believe, unless one coil went earlier but wasn't noticed until the second one went as well.

looking at the wiring diagram, i can't understand why they need a 5 terminals relay at all for the low speed. the "normally closed" terminal seems redundant? unless you need to short both the high and low speed terminals of the fan motors inorder for the high speed to work? any sparky here like to comment?

[Cheap6]

Yep, both windings in both of the motors (on the early VT) are required for high speed fan operation. The normally closed switch contacts in the 5 pin relay ensures that both high and low speed (= 4; 2 x 2) windings are switched on by the high speed relay even if the low speed relay doesn't work.

A consequence of this is that when testing the fans' high speed operation the 5 pin relay has to be in place or at least the normally closed terminals jumpered together.

Either of the windings in the fan motors can fail independently of the other.

You might try checking the resistances of the fan motor windings also.

[Rhin0o8]

I Own a Series I VT Berlina.

As for the fans starting up when the A/C is put on, Mine starts the fans ALWAYS .... even first thing in the morning when Engine temp is well below 35 Degress

[tk55]

thanks rhino08, we had already established that fact but thanks for confirming it again

cheap6, i see that you know exactly how the fans work. so there are 2 seperate windings in the fan motor, one for low and one for high speed. thus 4 wires altogether. i tried to remove the fan connector so that i can measure the coil resistance but the connector seems hard to come off. is there a trick?

anyway i measured them plugged in. measuring from the 12v supply connector, the black wire to both motors are opened. the others has only about 1.5 ohm. what i don't understand is, when the 12v supplies are plugged in, i expect the black wire to show zero volt, but it has about 10v still!!! how does that work? does that mean the black wire is not completely opened but has very high resistance? i'll try measure that again with the multimeter at high reisistant range when i had a chance. it was freezing outside yesterday

btw i'm not so sure you need to short both fan motor windings for the high speed operation. when i short pin 87A of the low speed relay terminal to earth, the fans came on. when i short pin 87 of the high speed relay terminal with the low speed relay removed, the fans came on as well.

how expensive are the fans? i might just wire a bypass switch for the high speed and use it manually when in slow traffic

[Mayte123]

I don't think the fans are expensive, i remember walking past them at repco and they weren't too bad (can't remember the price) but if it helps, start your car with the computer in diagnostics mode (hold mode and "up" whilst starting the car) and switch to temperature mode (T) and you can see the actual temperature and see exactly when the thermostat opens up etc. Also might be handy if your going to install a manual switch instead of the relay (if so i would suggest also making it so that it switches with the aircon button).

[tk55]

thanks mayte123. the engine temp went up to 89deg before coming down. in an easy traffice condition it's running between 86-89deg which is very normal. cruising on the freeway it's pretty much stayed at 86 deg constant.

but in very slow traffic situation the cooling system become insufficient and started to go higher than 90deg. this is where it needs the assistance of the low speed fan. normally you can either put the aircon on so that it's on low speed constantly, or you wait till it gets to 104deg where the low speed supposed to comes on. but with the broken low speed windinds, the temp would keep rising until the high speed kicks in, apparently at 112deg!!! ouch, too hot for comfort......

if i were to do the bypass job, why did you suggest to make it switches with the aircon? i was only going to use it when in slow traffic. i use the aircon alot and i often make trips that takes longer than 1 hr. can the high speed fan handles that if it's on constantly for that long?

the only reason i can think of is if the aircon compressor needs the fan turn on for cooling, and it does not have a self-cooling fan built-in. would that be the reason?

i could easily re-wire the low speed relay control to the high speed relay so that when the low speed supposed to come on it turns on the high speed instead. what do you think of that?