420A drivers side radiator fan not working

[Th3DooM]

I drive a 420A GS. My driver's side radiator fan doesn't work. I checked nearly everything that could be related to that issue but haven't found any solution. Fuses, relays, cables, coolant sensor etc. ... when I push the A/C button both fans jump on. That's the only way to cool down the engine when it overheats.

I switched the relays and it still won't work. I tried a jumper wire on the relay terminals, power is present. Checking engine parameters with OBDII shows me that coolant temperatures are real or at least reasonable so the sensors should be okay.

I don't know where to look next. What should I do now?

 

[97gen2]

I also drive a 420a and pretty shore that's how they work because mine dose the same thing and it dose not overheat so you might want to look at your thermostat if you want to test this find the opening temp then boil water to that temp and put in the thermostat and see if it opens if it dose not open or it takes a higher temp to open replace it and do a flush to see if its plugged or restricted in some way this should help

 

[Mokkan]

This set up is common on a number of vehicles. One fan is controlled by the coolant thermostat and the other is used for the A/C. You can either turn the A/C on low when you need extra engine cooling or splice the second fan into the controls for the first...assuming the wires can handle the extra current.

 

[Th3DooM]

Thanks for the answers.

But I thought the thermostat is a mechanical unit and has nothing to do with triggering the fans? I thought the coolant sensor reads the temperatures and starts the fans...

I manipulated the thermostat . In that way it's always open so the car is at least cool for a longer time after startup. The car still overheats at traffic lights or in slow traffic.
Another funny aspect is that when I activate the A/C with a cool engine the fans won't come on. But after the engine is warmed up and A/C is activated at the same time the fans will kick on to cool down the engine. Why doesn't the drivers side fan come on without the A/C?

I don't want to mess up my cables with installing a seperate switch or another power supply, I want everything nice, clean and working

Sry for my english, it's not my first language

 

[Mokkan]

I should have been more specific. Its not controlled by the thermostat, but the coolant temperature sensor near the thermostat. The passenger side fan should activate based on engine coolant temp. I'm not sure if the driver side is only activated by A/C or if it should eventually turn on if the engine is overheating, though.

The A/C puts extra load on the engine and therefore the engine requires more cooling. If the engine is cool, the fans aren't needed, so they don't activate.

Maybe your coolant temp sensor is broken? Sounds like the simple solution is to keep your A/C on while you're at stop lights.

Your English is fine, no worries.

 

[T is for TURBO]

A 420A in Europe? I thought you guys got the 4G63 N/T over there?

 

[L1v1ng L3g3nd]

Hey Doom!

I have the same problem right now, only difference is that I am 4G63 powered.
I can start both fans via ecmlink without problem but the fan won't start automatically.
I didn't have the time yet to look up the coolant temp via ecmlink, but I will do for sure when I am done with my engine swap.

Just courious if somebody knows what the ECU does if the sensor is broken. Shouldn't it throw a CEL or something?

 

[CleverDSMusername]

i had this same problem with my 1g about 9 months ago...i'm not too sure how the 420a is setup in a 2g but my 1g n/t 4g63 has a coolant sensor in the thermostat housing and one in the radiator, what i did was replaced the one in the thermostat housing then let it run 'till the engine is warm enough to trigger the fans (but the fan still didn't work, so i took it back off and put mines back in then cleaned up the new one and got my money back) since that didn't work i replaced the one in the radiator and let the engine warm up again, the fans came on after replacing the one in the radiator. so if your's have a sensor in the radiator, i would try replacing it and if it doesn't work then just clean it up real good then get your money back.

 

[Th3DooM]

I do have a 420A powered Eclipse. I bought it from a soldier who lived in Germany for a couple of years.

Thanks for the advice, but there's no sensor on 2G radiators.

Well, i gonna try changing my thermostat housing sensor. But I can't believe it's the problem since OBDII readings and the gauge keep telling me that the temperature is too high, too. The ECU seems to know that the engine is too hot

@ L1v1ng L3g3nd (aka devilsplayground): Hi! Doesn't a broken coolant sensor fool the ECU and affect the fuel injection negativly?

 

[L1v1ng L3g3nd]

You should take a look at this:


Engine Coolant Temperature Sensor

Applies to All


Note:
There are 3 sensors in the thermostat housing:
•The A/C temp sensor is in the upper half of the thermostat housing
•The instrument cluster temp sensor is the smaller single wire tap
•The ECU temp sensor is lowest in the thermostat housing and points slightly downwards.

Symptoms:
If the ECU determines the sensor has failed, the failsafe function is to assume the car is warmed up. This should also cause a diag code of 21. If the ECU does not notice that the sensor has failed, it will remain in 'warm up mode'. This will cause the car to idle high even when warm, and may affect fuel mileage (for the worse).

Location:
In the thermostat housing

Testing Procedure:
The service manual describes a procedure of removing the sensor, testing it in a tub of heated water with a thermostat, etc. This is way to much work, and requires sealent to reinstall, etc. I think it's probably sufficient to test the resistance with the car cold and leave it at that. You could also (at your own risk) test the resistance after the car has been warmed up.
Here is the appropriate data:


Temp (C/F) K-Ohms
0/32 5.9
20/68 3.5
40/104 2.7
80/176 0.3

 

[Th3DooM]

You should take a look at this:


Engine Coolant Temperature Sensor

Applies to All


Note:
There are 3 sensors in the thermostat housing:
•The A/C temp sensor is in the upper half of the thermostat housing
•The instrument cluster temp sensor is the smaller single wire tap
•The ECU temp sensor is lowest in the thermostat housing and points slightly downwards.

Symptoms:
If the ECU determines the sensor has failed, the failsafe function is to assume the car is warmed up. This should also cause a diag code of 21. If the ECU does not notice that the sensor has failed, it will remain in 'warm up mode'. This will cause the car to idle high even when warm, and may affect fuel mileage (for the worse).

Location:
In the thermostat housing

Testing Procedure:
The service manual describes a procedure of removing the sensor, testing it in a tub of heated water with a thermostat, etc. This is way to much work, and requires sealent to reinstall, etc. I think it's probably sufficient to test the resistance with the car cold and leave it at that. You could also (at your own risk) test the resistance after the car has been warmed up.
Here is the appropriate data:


Temp (C/F) K-Ohms
0/32 5.9
20/68 3.5
40/104 2.7
80/176 0.3

Unfortunately that doesn't apply to the 420A There are just 2 sensors -one for the gauge and the other one for the fan(s):

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[Th3DooM]

Update: yesterday I parked in a multi storey car park and guess what? The driver's side fan kicked on when the temperature raised. I haven't changed anything on my car since my last post in this thread so it worked randomly without any problem and without the AC turned on. I hadn't the chance to check if it's working everytime now, but I think that's a good start.