945 230fk Electric fan runs jerky when starting cold engine

[Hebaristo]

Hi guys, this is my first post on this forum and my first Volvo car.
Bought a 940 230kf about a month ago, been doing a good top to bottom review. I have noticed that when starting the electric fan it jumps intermittently as if it had a false contact hitting the relay again and again. Look for the relay and the first thing I saw was the 1st speed wire cut and a small jumpered capacitor between the positive wire (30) and the 2nd gear. I removed it and left the plugs as they came from the factory. After verifying that the continuity in the cables was good, I checked the relay, seeing that it failed, I changed it for a new one from Volvo. My surprise was the electric fan kept on intermittently I thought that the fault could be in the ECT sensor. Change it, the problem continues. I have checked the ECT sensor plug, the relay plug, and the shock absorber turrets. I still have to check the ECU, I suspect that this is the cause of the problem, but my gut tells me that it is rare that the ECU only has this fault, a bad ECU from my experience usually gives more than one fault, fuel injection, etc. To say that the fault I have is only caused by the engine being cold, once it is hot everything is fine.
I have searched in all kinds of forums in the US and in my country (Spain) and I have not seen anyone with the same problem.
On the other hand, I am looking for a way to contact the user Loki to get an OBD scanner. Excuse my English (I am helped by Google translator).
If there is a subforum of presentations let me know, I don't want to be impolite.
Any help would be greatly appreciated. greetings gentlemen!
To say that I have looked at the schemes, the masses and I think that every corner, something must escape me

[Rversteeg]

As you are living in Spain, I guess your 940 will have airconditioning.
The fan is always controlled by the ECU, but if AC is present, it can also be started by the pressure sensor and pressure switch of the AC system. You will find these switches 7/38 and 7/40 at the front side of the AC condensor. You can easily see them through the front grille, left side bottom. There are three connectors in a row, you need to have the two on the right side. Disconnect the connectors one by one and check if this makes a difference.
Unfortunately if the fault is in one of the pressure sensors, the AC system has to be depressurized for exchanging.

A fault code reader can be made by yourself, you will find the necessary information somewhere on this forum. Don't expect too much of the results. The computers in the 940 are quite primitive and a fault code does not always point you in the right direction. One fault can trigger another and you end up with a lot of suspicious components.

Rob

[Hebaristo]

Thank you Rversteeg. I have jumpered the cables of the 7/38 and 7/40 switches and the electric fan works , I know that this is not much and that the switches themselves may be the cause of the failure.
I have just done a few kilometers with the car, once warm the fan seems to work properly. Then I tried to turn on the air conditioning and the sputtering in the relay has started and the electric fan has started and stopped again, started and stopped...
Another fact is that when I start the car, the blue air conditioning LED lights up a couple of seconds and then it turns off, could it be normal or is the LED warning me that there is something wrong? Thanks!
Edit: I have tried disconnecting 7/38 and 7/40, the error is still there

[Rversteeg]

A bit of a long shot, this info from the Dutch Volvo forum:
The E-fan control of the ECU was modified during 1997. This means that the last (and best) series ECUs (ending at -984) cannot be used without modification on pre-1997 models. Installing a -984 ECU in a pre-1997 940 will cause the E-fan to run if the speed drops below 20 kph.

If you have a pre-1997 940 it is worth checking the code of the ECU as it could have been replaced by a previous owner for a -984 version. Solving this issue is a matter of cutting/adding a wire in the ECU-connector.

Rob

[loki_the_glt]

PM sent.

[loki_the_glt]

Code reader now with Royal Mail for delivery to Spain; my second export order!

[Hebaristo]

Originally Posted by Rversteeg

A bit of a long shot, this info from the Dutch Volvo forum:
The E-fan control of the ECU was modified during 1997. This means that the last (and best) series ECUs (ending at -984) cannot be used without modification on pre-1997 models. Installing a -984 ECU in a pre-1997 940 will cause the E-fan to run if the speed drops below 20 kph.

If you have a pre-1997 940 it is worth checking the code of the ECU as it could have been replaced by a previous owner for a -984 version. Solving this issue is a matter of cutting/adding a wire in the ECU-connector.

Rob

My ecu ends at 984, the car is from late 1997, it has the correct ecu. I finally gave up and decided to take the car to the shop. I need the car to go to work, I don't have much free time either and when I have it I like to enjoy my family. I will update as my mechanic tells me. Thanks for the help!