02 S60 Ac makes cooling NOT to start.

[sergio]

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Hi again Regent


The fan starts and stops on its own command both on 100% and 50%

The AC relay is on all the time. Clicking on it does not affect anything. No "click" sound, nothing.
It does not start / stop the cooling fan.



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[draser]

It sounds like the CEM does not know that aircon is running. Do you see an input on CEM coming from AC switch?

[regent]

Your fan control is then fine. It is more likely that you have a problematic input.

The AC clutch relay should change state (ON/OFF as you switch the AC ON/OFF). If the computer thinks it is always ON, there is a problem with that input.

Try communicating with the CCM (Climate CTRL Module) and try to toggle the AC clutch ON/OFF from the CCM activations. You should hear it very distinctly with the hood open.

I believe you're looking at the same diagram like I have on my car; page 44 shows the EC Fan Conrtrol by the ECM.
As ECM monitors the input from the ECT sensor (7/16) and the one from the AC Pressure (7/8), the fan is commanded to run if one or both of these values should rise above a preset threshold: EC Tempreature, AC Pressure. Now, it's a different story if any of these two signals should become faulty.

For example, in the event that the ECT is starting to fail, the comp would comand the fan to run for no apparent reason.

In your case, I would verify the AC Pressure sensor's accuracy. Didn't you have that sensor replaced already?
Also, since the CF starts and runs 5 min after you turn off a cold engine, I would look at the ECT sensor output; I recall someone posed the T (deg) to R (Ohms) data somewhere here, so you may try looking at that as well.

[sergio]

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Thank you for your help Regent

So far you taught me something (no-relay-double-commend fan) and confirmed my suspicion about the reasons why the fan doesn't go on when needed.
It must be either AC sensor or the coolant sensor. I couldn't (still can't) decide which one of the 2 is the culprit. Why the coolant sensor doesn't trigger the fan when the coolant temp goes beyond 92 C (my thermostat type). It should.

Anyways I did what you suggested but the "activations" in CCM is gray. I can't go there

Does the engine have to run this time?


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[regent]

The engine has to be at zero rpm (not running) with the ignition key in pos. II to run these tests. Not sure why yours are greyed out (could be firmware but I do not know for sure).

I am beginning to think that the above tests may not give you conclusive results at all as the components you would be testing have already been confirmed to be operational.

I suggest you first concentrate on the sensors beginning with the ECT; it is a good candidate for an offender.

See this thread for ECT calibration:
https://www.matthewsvolvosite.com/forums ... or#p160670

[sergio]

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Unable to read the status of the sensor on Vida and since I need to move the car I decided go manual.
I removed the fan with its casing and connected couple of wires and will have the fan work either full time like the old time (mechanical fans - despite the speed) or have it run at will. I rather run the engine at lower temp than see it go up in the air for over heating.

I will post the results later after the test drive.

I learned few things;
- The red wire [A1] going to the fan is always live +12 volt. Even with key off the ignition!
- BOTH ; White AND Black wires ending in the fan motor [6/29] are live + 12 V all the time.
- It must be [B1] coming from ECM that dictates the behavior of the fan motor

I think the white wire going to fan motor should be positive.
I also wonder if the rotation direction changes with polarity (answer later)


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[sergio]

Results of testing

Several few (5-15) minutes urban drive, city temp 88F a little slow traffic.

The thermostat works perfectly fine; the coolant temp stays between 185 and 193
Tried the AC on few occasions. Sometimes it engages others it doesn't . Coolant temp in the range.
I think I will try the bread clip for the AC.

Still have to figure out which sensor should be cleaned / replaced etc.

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