Radiator and Condenser fans speed is slow

[doctor]

I have a 1996 Diesel Corolla(Indus One).Its radiator fan fan works perfect when it operates in direct mode and the condenser fan too works fine when AC is switched on in the direct mode of rdiator fan.

But when the radiator fan is in the auto mode and AC is switched on, both the fans run but in slow speed as compared to the direct mode.

Showed to different electricians but no one could tell about the fault and everybody has his own solution of the problem which is not acceptable to me cause in the end they will either put a relay or disconnect the condenser fan from its original connections and connect it to the radiator fan wires directly and the problem will remain unsolved.

[Xulfiqar]

Thats how toyota originall wired up the fans, they operate in series for low speed and parallel for high speed. The system is made up of 3 relays

The series (slow speed) runs with A/C by default and only goes high speed when the high pressure switch on the A/C liquid line or radiator fan switch open up. This causes fan relays to make the circuit parallel for both fans causing them to run full speed.

Don't assume this is bad, its perfectly normal, and if an electrician tries to screw it up - wear some steel toe boots and kick him square and hard between the legs.

[hash4u]

did u try checking/replacing the fuse for it in the engine bay?
also get the radiator fan relay checked

[Xulfiqar]

did u try checking/replacing the fuse for it in the engine bay?
also get the radiator fan relay checked

WHY?? when the system is working like it should..

[hash4u]

thats for doc to answer actually
why is he experimenting with the fans if their basic functionality is fine

probably car heating up or something

[doctor]

@Xulfiqar

Thanks a lot.But Can you explain this further

"The series (slow speed) runs with A/C by default and only goes high speed when the high pressure switch on the A/C liquid line or radiator fan switch open up".

I mean when is it that high pressure switch on the A/C liquid line or radiator fan switch open up?And how to check wkether this is happening in my car or not and where to locate these switches in my car and the radiator fan switch is I guess the one attached to radiator if I am not wrong which is used for making fan direct or auto?And what are the functions of three relays but only two fans?

I have one 2004 Diesel corolla(Indus one).In that I guess the wiring is different as it has no condenser fan and both are on inside towards radiator and runs at full speed in auto mode..

[doctor]

@Hash4u

No over heating issue now as I changed its radiator in September 2011.Actually some wise electrician installed three fans in this car.One fan running with the radiator switch and the other two running with AC switch.I removed the condenser fan as I assumed that 1996 Corolla fan setup should be like 2004 Diesel Corolla which has two radiator fans and no condenser fan.But later I saw in another 96 Diesel Corolla that the condenser fan is there and there is only one radiator fan.So I removed the 2nd radiator fan and installed the condenser fan back again, and thats when I noticed this thing.I thought it might be some problem and then you know electricians in Pakistan they only know of adding relays and cutting wires.....whenever I go to some electrician for work I first ask him to diagnose what it is and tell me and only then I allow them to work.If thats not done they will simply ruin the thing.

[doctor]

@Hash4u
@Xulfiqar

Let me tell you an amazing thing.The heater valve in the engine bay of my car was missing too and as you know the AC mechanics favourite thing is to disconnect the hot water pipe from the heater connection and reinsert it back into the engine so that the hot water recirculates into engine and does not come inside to heat up the fan air and they assume the AC works fine then.I hate this thing simply but it was done when my younger brother took car for AC service last year.When in this winter I needed heater I switched it back in normal position.But the air was even hot when the lever was on cold.I assumed something is missing and asked my mechanic that waht is this steel wire hanging for in engine bay...he said its actually for Japanese cars in which there is a valve to open or close and run or stop the flow of hot water for the heater inside the car......I purchased the valve from Peshawar and installed and showed then it to the mechanic who said that it only comes in Japanese corollas......And may be every mechanic is not like this but I think the majority are "lakeer k fakeer".

[Xulfiqar]

@Xulfiqar

Thanks a lot.But Can you explain this further

"The series (slow speed) runs with A/C by default and only goes high speed when the high pressure switch on the A/C liquid line or radiator fan switch open up".

I mean when is it that high pressure switch on the A/C liquid line or radiator fan switch open up?And how to check wkether this is happening in my car or not and where to locate these switches in my car and the radiator fan switch is I guess the one attached to radiator if I am not wrong which is used for making fan direct or auto?And what are the functions of three relays but only two fans?

I have one 2004 Diesel corolla(Indus one).In that I guess the wiring is different as it has no condenser fan and both are on inside towards radiator and runs at full speed in auto mode..

the highlighted part means that whenever the A/C is switched on by the driver, the fans will run low speed - the high speed fan mode is controlled by

1 - A/C high pressure switch in the liquid line
2 - engine thermofan switch

old Toyotas use "cut-off" relays to operate the fans, meaning that as soon as the ignition key is switched on the relay is switched on and is kept on. When the relay is ON the controlled circuit is "CUTOFF" and when the relay is OFF the controlled circuit is enabled to work.

To prevent the system working with key off - there is a main relay in the fuse box which grounds out all such connections. It sounds confusing but its quite easy.

anyway - the cutoff system works when any switch is disconnected from the circuit or it activates itself (by whatever medium its facing) - when the liquid line pressure gets high the high pressure switch connection disconnects from ground causing the high speed relays to switch off and force the whole circuit to go parallel taking both fans to full speed.

The newer corollas (diesel ones made by IMC) also use the old system, the petrol ones (1 large fan) have an entirely different circuit with a step down resistor in it located behind the left headlight bolted to the chassis of the car. That resistor is for low speed fan.

[doctor]

@Xulfiqar

1.Where is the high pressure switch located in the liquid line of AC in 1996 Diesel corollas and in 2004 Diesel corollas?And how can I check whether it is there or not?

2.Secondly, if AC is switched off, and the radiator fan switch is controlling the radiator fan then it should run at full speed when this switch turns it on automatically or it should be at low speed?

3.Are the engine thermofan switch and radiator fan switch one and the same things?And what is the operating temperature for this switch to switch on the fan automatically?

4.And also check this thread as well so that I can benefit from your advice https://www.pakwheels.com/forums/engine-transmission-powertrain/187537-clutch-hardness-2004-diesel-corolla

[Xulfiqar]

The high pressure switch would be an oval connector with 4 pins, this is a combination hi-pressure trigger/low-pressure-cutout switch. It would be either near the firewall in the engine room or near the front right of the car at the upper side.

In the diesel corolla, with A/C switched off the fan is solely controlled by the engine thermoswitch on the radiator, It cuts out ground and makes the fan work full speed.

In the newer petrol models with ECU controlled fans, the ECU can also switch the fan on at low speed without A/C. Usually it immediately trips it to full speed. The newer system with the one large fan works on 2 relays only - relay one controls the positive side of the circuit and is a simple SPST relay, relay 2 controls the ground path, Its a SPDT relay, and by default it routes ground to the fan via a resistor, the other path in which the relay switches on to operate is a direct path to ground for full speed fan.

[doctor]

@Xulfiqar

Thanks again and Answer to these questions is still awaited

3.Are the engine thermofan switch and radiator fan switch one and the same things?And what is the operating temperature for this switch to switch on the fan automatically at full speed?

[Xulfiqar]

@Xulfiqar

Thanks again and Answer to these questions is still awaited

3.Are the engine thermofan switch and radiator fan switch one and the same things?And what is the operating temperature for this switch to switch on the fan automatically at full speed?

yes they are the same

[SER_GTR]

Lolx........Its How They WORK......!!
MY AE101 Trigger Up Both Fans On Low Speed When A.C Is ON....As Engine Hits The Desired Normal Temp Range....They Automatically Becomes High Speed.....!!

Just Make Sure The System Is Working....Start A.C And Wait For Car To Reach Normal Temp Range...Once Reached Normal...Fans Will Automatically Become High Speed ....!!

[SER_GTR]

Thats how toyota originall wired up the fans, they operate in series for low speed and parallel for high speed. The system is made up of 3 relays

The series (slow speed) runs with A/C by default and only goes high speed when the high pressure switch on the A/C liquid line or radiator fan switch open up. This causes fan relays to make the circuit parallel for both fans causing them to run full speed.

Don't assume this is bad, its perfectly normal, and if an electrician tries to screw it up - wear some steel toe boots and kick him square and hard between the legs.

Hahaha...LMAO....How About Using A 5Rs COIN Trick

Drop A COIN...Ask For A Pickup......And.................................

[SER_GTR]

If You Also Disconnect The Auto Thermofan Switch (If You Have Auto Fans) Making Fans Running Direct.........Then Fan Will Run On High Speed....!!!

[Xulfiqar]

Hahaha...LMAO....How About Using A 5Rs COIN Trick

Drop A COIN...Ask For A Pickup......And.................................

This technique is very different in South and North Pakistan, - which one are we discussing here?

[harris24742]

I've a 2004 corolla xli. Got its ac serviced from mian car ac at lahore. He replaced the genuine ac switch with a non genuine one. It soon malfunctioned and upon my complaint he made a direct connection of it. Hence the ac fan kept on running direct. During the winter I asked him tofix it and instead of putting the genuine switch he attached a relay.
In about two weeks i noticed that the fan did not run at its full speed when ac was running. The fan would run at full speed only when the car would reach the optimum temperature.

These days, I have noticed that sometimes the fan runs at full speed when ac is on and upon switching the ac off, it shuts down. At times, the fan while running slow, acts as if it is trying to rev up but loses current and hence slows down instead of operating at full speed.
I need your urgent Help if the relay needs to be replaced. I do not know that should the fan be operating at slow speed on ac or is it supposed to run at full speed even when the car is ice cold on ac

The high pressure switch would be an oval connector with 4 pins, this is a combination hi-pressure trigger/low-pressure-cutout switch. It would be either near the firewall in the engine room or near the front right of the car at the upper side.

In the diesel corolla, with A/C switched off the fan is solely controlled by the engine thermoswitch on the radiator, It cuts out ground and makes the fan work full speed.

In the newer petrol models with ECU controlled fans, the ECU can also switch the fan on at low speed without A/C. Usually it immediately trips it to full speed. The newer system with the one large fan works on 2 relays only - relay one controls the positive side of the circuit and is a simple SPST relay, relay 2 controls the ground path, Its a SPDT relay, and by default it routes ground to the fan via a resistor, the other path in which the relay switches on to operate is a direct path to ground for full speed fan.

[Xulfiqar]

I've a 2004 corolla xli. Got its ac serviced from mian car ac at lahore. He replaced the genuine ac switch with a non genuine one. It soon malfunctioned and upon my complaint he made a direct connection of it. Hence the ac fan kept on running direct. During the winter I asked him tofix it and instead of putting the genuine switch he attached a relay.
In about two weeks i noticed that the fan did not run at its full speed when ac was running. The fan would run at full speed only when the car would reach the optimum temperature.

These days, I have noticed that sometimes the fan runs at full speed when ac is on and upon switching the ac off, it shuts down. At times, the fan while running slow, acts as if it is trying to rev up but loses current and hence slows down instead of operating at full speed.
I need your urgent Help if the relay needs to be replaced. I do not know that should the fan be operating at slow speed on ac or is it supposed to run at full speed even when the car is ice cold on ac

Did your electrican try to bypass the resistor

[8502]

I had this problem in my gallant 2.5 vr, fan worked changed speed from low to high relay, fan module all checked but fan worked normally at both speed I mean not that fast like the local cars fans, faced some heating issues only during stops at traffic as soon as I move the needle would get normal, but when I direct them by just pulling the ECU wire out they run at full speed and no heating issue at all even if you are with AC on for 2 hours at full stop. So the issue is more air needed by engine. I spent many hours and hard earned money to increase the speed in auto mode but all in vein I can't be changed because that's how they designed the system, best option use direct in summer and auto in winter, no harms to engine in direct mode just the car will take 2 more minutes to reach optimal temperature.