Direct connection radiator fan is harmful

[Xulfiqar]

the theory part is correct but the problem in an SU carb is that there are some precision metering parts inside that slide on each other, running on CNG makes for a dry running carb which causes the parts to wear out.

The other bit is that some CNG mechanics have cut the reaction spring behind the sliding piston in the carb to compensate for fuel being added from the of the sliding piston rather than above the throttle plate and below the piston.

[afarooqi]

By the pictures you are showing, the part you are calling the temperature sensor is actually the fan switch and the socket you are showing with your hand is the A/C high pressure switch socket

The circuit is wired up as

relay - 2 pin A/C switch - single pin fan switch.

Its done this way because the toyota switches work in reverse - if the A/C high pressure switch opens up the fans will turn on, If you are not using A/C the switch remains shorted connecting the fan switch to ground and the circuit only opens when the single wire fan thermoswitch breaks ground connection hence running the cooling fans

The gauge temperature sensor is before the thermostat not after it. It would be near the water pump, look at the back of the engine for a single wire sensor.

Take a multimeter or line tester and trace the wires, one wire from this socket should be leading to the fan switch, and one wire should be leading to the relay in the fuse box. It would confirm this is the A/C high pressure switch.

Does your car have 1 or 3 fan relays? - 1 relay is for single speed fan and 3 relays are for dual speed fans, they work on low speed (in series) with A/C function and only switch to high (parallel) when the A/C pressure switch or engine thermoswitch opens up taking the fans to full speed.

here is a general diagram to make it simple

Thanks Xulfiqar bhai for explaining in detail. Now I got it completely, and found that some idiot electrician had connected fan switch to temp sensor wire. I have connected it to proper place, and fan is AUTO now. Just I have to hook up the AC high pressure switch to make fan running on AC continously.

As you have asked, my car has single relay for fan.

Driving my car is more fun now, oily silencer is now in rusty color without any signs of oil, pick is great, and idle is smooth and engine sounds healthy. more over, after driving 2000 kms, engine oil has not yet turned black, whereas, previously without thermostat, it gets black after 500 kms.

Thanks you for guidance, patience and explanation.

[Xulfiqar]

if your car has two cooling fans, one behind the radiator and one infront of the condenser behind the bumper fit originally from toyota then you have 2 speed fans. (its the original A/C setup of old FWD corolla)

The low speed works by running the fans in series and is activated by the A/C switch inside the dashboard, when running A/C it would only go high when either the engine temp gets high and the switch opens up or the A/C high pressure switch opens up.

Easy way to install a toyota high/low pressure switch is to buy a hi/lo oval switch from an Indus corolla and its own special connector, it has both switch functions of low pressure system cut off and high pressure switch for making the fans run in series (i.e. full speed)

If your car originally did not have A/C then you would not have the dual speed setup.

[imran2d]

Mr.Xulfiqar, as I have Toyota 2.0D 1998 (indus) with original AC so, I observed that AC fans run on one speed only, do you think that I am supposed to have dual speed fans on this model.

[Xulfiqar]

Your car also has 2 speed fan setup, when the A/C is first switched on the fans should run slow - and if the A/C pressure is not high (e.g. ambient temperature not very high) the fans will continue to run slow. They only go to full speed when the A/C high pressure switch opens up or the fan sensor opens up.

its the same circuit as I explained above. If your fans run full blast high speed all the time with A/C verify that the wiring has not been rigged or the A/C gas is not overcharged, overcharged gas causes very high pressure in the system which will open the high pressure switch to switch the fans to full speed.

The speed control is

fans in series = slow
fans in parallel = fast

and is accomplished by three relays

[afarooqi]

Xulfiqar bhai,
After installing T-stat and auto fan switch, my car did good in winters. But since yesterday, it is somewhat like summers. An abnormal thing I obeserved that when temp gauge reaches middle, RPM gets de-stabilized. It drops to 400-600. What could be possible reason? Do I need some other adjustment as well? like tappets etc?

[Xulfiqar]

Xulfiqar bhai,
After installing T-stat and auto fan switch, my car did good in winters. But since yesterday, it is somewhat like summers. An abnormal thing I obeserved that when temp gauge reaches middle, RPM gets de-stabilized. It drops to 400-600. What could be possible reason? Do I need some other adjustment as well? like tappets etc?

check the carburettor hot idle compensator and check for any vacuum leaks on the inlet manifold and vacuum pipes too too. It maybe caused by a leaking vacuum pipe routed via a heat switch.

[cyrius]

little wisdome is dangerous

after reading all the post i must say people are still ignorant

the thread starter has clearly told the whole story but most of ur not understanding i think its in eng thats why,

engeins and cooling systems are made after research of centuries and with time they are enhanced and modified. when they came they are with tstats and auto
who are we to alter their config u think ur wise and those japanies are stupid who put tstat and auto.

so switch to tstat and auto
for lahore guys any problem give me a call always here to help u got workshop in cantt. 03214441189

[zshan2000]

Hi,
I need help from PW users.My margalla 97 is running on Direct Radiator fan.
I have no issues with heating car works well with AC.
I wanted to know how to make thermostat switch works automatically.
Any suggestions with pictures would me much helpfull( Xulfiqar )

[zshan2000]

Any one ????????????????im still looking for some answers

[Xulfiqar]

what position does your temp gauge normally stay on?

[zshan2000]

what position does your temp gauge normally stay on?

With AC running it never crossed half,Never noticed any thing abnormal.
With out AC 25 % of half

[Xulfiqar]

that means that your engine is missing the thermostat valve, get that installed. Then do the fan bit.

In normal condition the engine temp should remain at half and it should get to half temperature within 10 minutes of driving.

[zshan2000]

that means that your engine is missing the thermostat valve, get that installed. Then do the fan bit.

In normal condition the engine temp should remain at half and it should get to half temperature within 10 minutes of driving.

any idea which thermostat valve i should buy?

[Xulfiqar]

the original one.

[zshan2000]

I have checked in few shops ,they said original is N/A and none of the mragalla's are using it.some of them suggested to use the Cultus T-stat valve.
The worst part is all of them questioned me why you wana make it auto.:-#

Xulfiqar Please advise

[Xulfiqar]

it uses the same T stat valve as a Baleno or even the cultus one will fit and operate the same. The shopkeepers asking you the stupid question are just selling boxes, they have no idea of any science behind the parts they sell or how it works or why its important.

[zshan2000]

Thanks boss

Sent from my MT11i using Tapatalk 2

[ToxicDevil]

Where is the THERMOSTAT VALVE located?

[Xulfiqar]

inside the thermostat housing