Thanks Sir! OK as promised I'm back with an update on the topic. The new fan module from China didn't make any difference at all so I'm having to return it. I did visit a mechanic shop at chah sultan to get my radiator cooling fan motor replaced after the original one died on me all of a sudden. The engine hit the max heat mark for about 90 second and I took over control. Apparently, things are fine and the gasket survived! Alhamdulliah!
Back on the topic, so at that mechanic shop I got a chance to test another module but no luck at all. We tried to plug in a different temp sensor as well just in case, negative! So both the temp sensor as well as the fan module seem to be fine. We're then left with the air conditioner pressure switch or the ECU itself.
For the pressure switch, given the AC works fine with no problems at all. I think we can probably rule it out too. Correct me if this is wrong! I'm just a student.
Now for the ECU, I tested its signal wire to the fan module, I figured the fan needs 13 volt of ground to switch off the fan. I tested this wire using a multi-meter, one terminal of the meter to the signal wire and the other terminal to battery positive. When the fan is operational at high speed the reading is about 5-6 volt. At slow fan speed, the reading is 3 volts. And once the wire has full ground from the computer i.e 13 or so volt the fan is off.
So it looks like the problem is with the ECU but I'm sort of confused. Is it the ECU itself or is something "making it" to give those false readings? The fan starts running on freezing cold engine and it would sometimes turn off after like 2-3 mins, sometimes after a few secs and sometimes it wouldn't turn on at all (which is what I want but it only behaves when it wants).
I stopped by another ustad in saddar the other day and told him the story. He asked for 4000 to repair the ECU. I have spent 6000 on this ECU already for a slightly different problem about 3 months ago, at that time the fan was literally on all the time. And now its behavior is random.
Since it's a random problem (not as random at this point, it's acting crazy more frequently), I'm not sure how to go about solving it. What if the fan doesn't misbehave when I take it to the shop and if it does, and I end up getting it repaired and paying 4000, how do I know if the problem is actually solved? Should I ask for warranty or something?
What it is in the ECU that could cause the problem? Why someone can't open it up and take a look himself? Is it too complex? If it is how come an ustad is going to figure it out.
If anyone knows a good/educated/tested repairer in RWP or ISB, PLEASE let me know. Or if it's not the ECU in the first place what could it be?
Thanks for your time.