Overheating and electric fan

[Mint]

I suspect that as well, but then why one speed is working?

I think there are two separate coils in the motor body.
IIRC the motor is switched by a relay, one for high and another for low speed. It was a long time ago.
Maybe have a look at the wiring diagram for your car. They are in the resources area on this forum.

 

[Rudyrov]

Have you checked your engines thermostat, perhaps using an infrared temp probe to monitor the opening as the engine warms up?

 

[Mint]

I think there are two separate coils in the motor body.
IIRC the motor is switched by a relay, one for high and another for low speed. It was a long time ago.
Maybe have a look at the wiring diagram for your car. They are in the resources area on this forum.

Edit, just checked the wiring and relay K21 is for low speed and relay K22 is for high speed.

This diagram is for an M52 but I shouldn't think yours will be very different...

 

[adis]

Have you checked your engines thermostat, perhaps using an infrared temp probe to monitor the opening as the engine warms up?

I don’t have an infrared temp device to check. I checked the return hose to the radiator when the gauge needle is over the center area and the hose is very hot and solid, but I don’t know the temp exactly. I am thinking to replace the thermostat if the fan is working and the relays are good.

 

[adis]

Edit, just checked the wiring and relay K21 is for low speed and relay K22 is for high speed.

This diagram is for an M52 but I shouldn't think yours will be very different...
View attachment 341893

Thank you. Based on the diagram there are 2 fuses 16 and 40 in front of the relays. I checked the fuse box in my Zed and there is no fuse 40 and it seems the box is not equipped with this fuse, even though on the cover of the box it says that fuses 16,40 and 48 are related to fan somehow. 48 is indicated to be under the steering wheel but I can’t see anything in there just the obd plug. How can I test the relays? The one that I believe is for low speed k21 is magenta/violet and has the code v23134-e57-x181 and the k22 is yellow and has the code v23134-e59-x107. Can I reverse them?

I also found this site https://www.startmycar.com/us/bmw/z3/info/fusebox/2001 where it has an interactive map for the fuse box but the relays for the fan are in a different place!!! Also it says that F40 is for fog lights and my Zed doesn’t have, so this is why it is probably missing?!

I’m very confused now. I’m thinking to connect some wires directly from the battery to the fan plug to check the fan stages directly. Is this a safe way to test or do I damage the fan?

 

[Mint]

Thank you. Based on the diagram there are 2 fuses 16 and 40 in front of the relays. I checked the fuse box in my Zed and there is no fuse 40 and it seems the box is not equipped with this fuse, even though on the cover of the box it says that fuses 16,40 and 48 are related to fan somehow. 48 is indicated to be under the steering wheel but I can’t see anything in there just the obd plug. How can I test the relays? The one that I believe is for low speed k21 is magenta/violet and has the code v23134-e57-x181 and the k22 is yellow and has the code v23134-e59-x107. Can I reverse them?

I also found this site https://www.startmycar.com/us/bmw/z3/info/fusebox/2001 where it has an interactive map for the fuse box but the relays for the fan are in a different place!!! Also it says that F40 is for fog lights and my Zed doesn’t have, so this is why it is probably missing?!

I’m very confused now. I’m thinking to connect some wires directly from the battery to the fan plug to check the fan stages directly. Is this a safe way to test or do I damage the fan?

Sorry, can't help with the relays as I did not have to fault find mine. But to test them, remove them from the car, and connect 12v across the coil and you should hear the relay click as it operates.
And yes you should be able to get the fan running directly using a 12v battery. It does take a fair bit of current though, hence the relays.

 

[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 did take the car for a ride today on a road for 15km driving mostly constantly with 70 km/h, no AC and the gauge needle stayed in the middle. While parking the gauge needle started to go towards the next line on the right and I activated the AC. The needle came back in 1 min or so to the center. After 1h break (with temp outside at 30C+) I started the car and returned home. The needle was in the middle when I started the car. The AC was on. After 7 km or so, I switched off the AC. Shortly after (not sure if related), the gauge needle started to climb reaching the next line on the right. I switched on again the AC but nothing happened. I put the blower on 4 and full hot and the needle started to go down but not reaching the middle. When I arrive home and parked the car, opened the hood and the fan wasnt working. The gauge needle was on the next line from the middle. The return hose from the thermostat in the engine was very hot, but the radiator body was not (tested with my hand).

I'm totally lost. I still didnt figure out why the fan sometimes works and sometimes not. Also, on which speed. I dont have all the fan relays in the fuse box - and it seems the car is not equipped with both of them from factory.

I will bleed it again and if this doesn't solve the problem then I will replace the thermostat in the engine (as this is less expensive than others) and then probably the radiator as it is slimmer compared with the factory one which I have changed. Still not clearing the fan issue speeds is bothering me. Sorry for the long message but it frustrates me a lot that I cant fix the problem!

 

[Mint]

Could still be the low speed of the fan not operating correctly.

 

[adis]

I bled the car again with the front lifted up. Funny enough the fan kicked in several times while the gauge needle sat in the center.
i also removed the relays while the fun was running, first K21 and then K22 and the fan stopped, but started again when i put them back.
Then I took the car for a ride and in about 10 min or so, the gauge needle started to climb again. I put the AC on, but nothing happened. I continued to drive and the needle slightly passed the next mark on the right.
I found a parking spot and parked the car. The fan was not working. I removed the plug from the temp switch in the radiator, shorted the pins that put the fan in the stage 2 (I believe), so it runs continuously and the temp started to come down to the center.

Conclusions so far:

1. Fan speeds are working, but somehow I cannot get each speed by shorting the pins at the radiator temp switch, only one.
2. Relays seem to be okay, at least by removing them one by one, interrupts the fan running
3. The return hose to radiator was not cement solid like the other days and not hot. But the temp switch on the radiator was very hot.
4. Can’t explain why the temp is not going down on high speed on the road, even with fan not working, with the AC on. Drove with 60-70 km/h.
5. Also, it seems that when the front part of the car was lifted up for bleeding the fan started several times to cool the engine. That seems to be a normal operation of the fan, as it should be. Can’t explain why the fan is working fine in that position.

work in progress. If any other ideas, please let me know. What else I need to check.

I’m thinking now to buy a new thermostat, then a new temp switch and a radiator.

 

[adis]

I replaced the thermostat. I also tested the temp switched and saw that it doesn’t kick in at 85-88 as it should, so I re-used the original temp switch. I also realized the low speed of the fan can only be tested with the engine running when bypassing the temp switch. The Z3 runs smoothly now.
Problem solved. Thanks.

 

[Mint]

Good to see you've sorted it out