Overheating and electric fan

[adis]

It seems that the electric fan is not kicking in on low speed or at low temperature. It does only when the temperature goes to 110C or so. I guess this is the high speed.

I have changed the radiator, the thermo-switch on the radiator. When I have the AC on the fan starts for 5-10 seconds then stops for 1-2 seconds and then starts again - I don’t think this is normal. I heard that when AC is on, the fan has to work all the time.

I like to make some tests on the fan to eliminate the problems one by one, I suspect that low speed doesn’t work, either because of a fuse or a relay or the wire or the fan motor itself.

Did anyone have these problem and have a troubleshooting guide or any ideas where to start before I go and change thermostats and fan?

My Zed has an M43 engine so it has only an electric fan placed after the radiator.

 

[Rudyrov]

Sorry to say I have no experience with the 4 Cyl. engine. My 6 Cyl 2.8 did have a radiator failure a few years ago so I replaced the radiator with an aftermarket all aluminum one and deleted the engine driven fan and replaced it with a large fan pulling air through the "rad".
I also replaced the thermal switch in the upper radiator (exhaust side on my car) and am using a thermal switch with relay to trigger the aftermarket fan.
My OEM front fan does work with the AC but my AC needs work so I rarely try it, I have seen it work but I mostly rely on the aftermarket fan for engine cooling.

 

[adis]

Thanks for the info. When you turn on the AC the fan starts and works all the time or it starts and stops cycles?

 

[Rudyrov]

Thanks for the info. When you turn on the AC the fan starts and works all the time or it starts and stops cycles?

I am not sure if it cycles with the compressor or is just on whenever the AC is engaged.
My guess is it runs concurrently with the compressor.

 

[adis]

If you can check pls let me know. Mine starts then stops for a few seconds then starts again and so on. It may be a relay problem then, or bad contact in the plug I guess.

 

[Kenhayes247]

Does the car overheat? Is the temperature gauge needle heading towards the red zone when the car is hot? If it stays central and the fan kicks in at about 90 to 110 degrees I would suspect it’s working correctly.

When you switch the aircon on I would expect the fan to run immediately even if the car is not at temperature and continue to run until the cabin temp is met. If it’s cycling then the first thing I would check is the ac pressure. Tested on the low side. Low pressure will allow the ac clutch to engage the fan to start but then stop within a few seconds as it gets too hot and shuts down to prevent damage to the compressor.

 

[adis]

The car overheats indeed. Not immediately, but after some time the gauge goes at the next mark on the right from the center. Then the fan kicks in. So I believe something is wrong either with the thermo switch on the radiator or the fan not working on the first speed. But I changed the thermo switch… is the fan having fuses that I need to check? If I take the plug out of the thermo switch and short the pins in pairs on the plug would that be a good way to test the fan? There is another plug where the fan is connected which is placed somewhere under the radiator.

I don’t know how to check the pressure on the AC, I guess the pressure of the gas?

 

[Duncodin]

If you're cruising (ie not thrashing it) up the motorway in top gear at 70mph then I'd expect there's enough airflow without fans. If it's overheating then it's not your fans. Look at thermostat, airlock, radiator flush.

 

[Kenhayes247]

Did it overheat before you changed the radiator?

 

[adis]

Well, it is a long story. It didn’t until I change the AC belt and I forgot to plug in the electric fan. So after that it was overheating shortly while I was in traffic. So I had leaks on the radiator (expansion tank) and changed it. It is not identical with the original. It is slightly slimmer. I have changed also the thermo switch.

However, before I start to replace the thermostat and others, I want to make sure the electric fan is not at fault, or a wire problem or maybe just fuses or relays, which where never changed.

 

[adis]

If you're cruising (ie not thrashing it) up the motorway in top gear at 70mph then I'd expect there's enough airflow without fans. If it's overheating then it's not your fans. Look at thermostat, airlock, radiator flush.

I will test it again on the motorway. But why the fan doesn’t start at 90C when engine is idling? It only starts when is on the next mark? This is why I suspect it is something with the fan. I only have one fan.

 

[Kenhayes247]

Personally I would start with making sure the system is bled correctly.

 

[Nodzed]

The car overheats indeed. Not immediately, but after some time the gauge goes at the next mark on the right from the center. Then the fan kicks in. So I believe something is wrong either with the thermo switch on the radiator or the fan not working on the first speed. But I changed the thermo switch… is the fan having fuses that I need to check? If I take the plug out of the thermo switch and short the pins in pairs on the plug would that be a good way to test the fan? There is another plug where the fan is connected which is placed somewhere under the radiator.

I don’t know how to check the pressure on the AC, I guess the pressure of the gas?

Theres three pins, ground, hi speed and low speed power. If you run a live to either of the power pins this should start the fan in each of the speeds, if it doesn't then the fan is most likely knackered. Or if you have a multi meter just check the voltage at the fan plug.

 

[Kenhayes247]

There is a guide on here somewhere that recommends filling the cooling system via the top hose disconnected from the radiator not the BMW recommended way. I followed this method and it eliminated trapped air ensuring I could rule out cooling issues with the engine

 

[adis]

Theres three pins, ground, hi speed and low speed power. If you run a live to either of the power pins this should start the fan in each of the speeds, if it doesn't then the fan is most likely knackered. Or if you have a multi meter just check the voltage at the fan plug.

Are you referring to the plug that enters the thermo switch on the radiator? I believe this has already a live in it, because I disconnected the plug and short the pins. The fan starts only on a pair of them, but on the other combinations it doesn’t. Would that mean a fuse or wire is faulty?

 

[adis]

There is a guide on here somewhere that recommends filling the cooling system via the top hose disconnected from the radiator not the BMW recommended way. I followed this method and it eliminated trapped air ensuring I could rule out cooling issues with the engine

I will definitely do that once I know the fan is working correctly!

 

[Nodzed]

Are you referring to the plug that enters the thermo switch on the radiator? I believe this has already a live in it, because I disconnected the plug and short the pins. The fan starts only on a pair of them, but on the other combinations it doesn’t. Would that mean a fuse or wire is faulty?

Should be a plug under the rad or somewhere in that area.

This may help

Video

 

[adis]

Thank you. I have done the following tests and measurements:

1. Unplugged the plug from thermo switch at the radiator. I shorted the pins brown (middle) and black and the fan starts. I shorted the brown (middle) and brown and nothing.
2. Found the fan plug under the radiator, unplugged and tested voltage per video above. Brown (middle) and Black measure 13.9V with AC ON. Brown (middle) and Blue measure 0.0V.

So now I think I can’t say the fan is faulty.

I opened the fuse box under the hood and I read 16,40,48 are related to fan. 16 is in place and okay. 40 is missing. 48 it says it is under the steering wheel. I can’t find any fuse box under the steering wheel!!!!

Any other ideas?

 

[Mint]

1. Unplugged the plug from thermo switch at the radiator. I shorted the pins brown (middle) and black and the fan starts. I shorted the brown (middle) and brown and nothing.

So now I think I can’t say the fan is faulty.

Not sure I agree with you. When I was testing my fan some time ago I could get it to run at both High and Low speed by doing what you did.
I think your fan is faulty.

 

[adis]

I suspect that as well, but then why one speed is working? Also, isn’t there a fuse for each speed stage of the fan?

Perhaps I can try to connect the fan directly to the battery and see if it works on each pair of wires?!