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Air condition compressor clutch not engaging
#1
Citroën Berlingo MK2 1.6i (TU5JP4) 2006 - VIN: VF7GJNFUC93352754

I bought the car recently and had the air conditioner re-gassed. The system has no leaks, 700g cooling agent was emptied out, and it was re-filled with 600g (according to specifications)

When I push the AC button the indicator lamp activates, but the AC compressor clutch doesn't engage.
I have checked the AC clutch by applying 12 volts directly - it engages and shortly after there is cool air flowing into the cabin. The ventilator fan also sharts shortly thereafter.

I made the following readings using Lexia (via Diagbox 7.62) having the AC activated (AC light on):

ECU (Injection Control) readings:
  • Air temperature: 23 degrees C
  • Air conditioning authorization: No
  • Air conditioning request input: No
  • Fan Unit Relay: Inactive
  • Rrefrigerant circuit pressure: 6604,7 bar.
    I disconnected the pressure sensor and got an open circuit error and a pressure reading of 921,6 bar.
    Those measurements would be okay if the unit of measure was millibar instead of bar. Is the Lexia software displaying a wrong unit of measure? What is your Lexia reading here?

BSI readings:
  • Air conditioning compressor control: Inactive (even though the light is on in the AC button)
  • Fan mid speed control: Inactive
  • Evaporator sensor temperature: 23.9 degrees C
  • Evaporator icing-up sapety status: Inactive
It looks like no command is sent to the AC compressor clutch - I have checked that there is 0 volts at the compressor clutch.

I cannot see from the user manual which fuse is supplying the AC compressor clutch - can anybody provide me a curcuit diagram for the AC system?

Any ideas what the problem could be? And why is the pressure reading that high?
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#2
Hi there welcome to the forum, not sure if this will help but looking at earlier wiring diagram look at engine fuse box Fuse A and C and on interior fuse box look at fuse F8 F15 F14 F30 and F26. According to the wiring diagram they all have something to do with the air con.
If its any help there is a manual download on the site if you have a search.
Good luck.
Are we there yet????? Huh
Ex 1.6hdi van now 3 seater 1.4 multispace
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#3
That's the most comprehensive technical 1st post I have ever seen on the forum, well done with your diagnostics.

However,  forget the technical stuff.....

Was the AC working when you got the car? 

If so why the re-gas?

Did the system work ok after you had had it re-gassed?

For how long?

.
My vehicle .... 2006 (m59) Berlingo Multispace Desire - 1.6 HDI 92 
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#4
(30-06-2018, 06:59 PM)Tomcat3 Wrote:  Hi there welcome to the forum, not sure if this will help but looking at earlier wiring diagram look at engine fuse box Fuse A and C and on interior fuse box look at fuse F8 F15 F14 F30 and F26. According to the wiring diagram they all have something to do with the air con.
If its any help there is a manual download on the site if you have a search.
Good luck.

The engine fuse box has fuses F1 through F18 (all fuses are good) - it hasn't any labeled A and C (I haven't looked at the maxi fuses underneath - I assume these are good, because I can measure 12V on both sides of each fuse when the right outputs are activated).
The interior fuse box (the BSI) hasn't got all of the fuses you mention, F8, F26 and F30 are not existing on my car. All interior fuses are good.
I guess the specific wiring diagram for this car is needed. I searched the forum and only found the Haynes book for mk1 models. I don't think the wiring diagrams in the book match my car.
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#5
(30-06-2018, 11:13 PM)jj9 Wrote:  That's the most comprehensive technical 1st post I have ever seen on the forum, well done with your diagnostics.

However,  forget the technical stuff.....

Was the AC working when you got the car? 

If so why the re-gas?

Did the system work ok after you had had it re-gassed?

For how long?

.

Thank you for the kind words.
  • The AC was not working when I got the car.
  • I had it re-gassed just to be sure that the system had no leaks and that the right amount of refrigerant was present. It was done by a small independent garage having the right equipment. He actually did it free of charge, apart from the 100 g  refrigerant he kept. 
  • And no, the system did not work after the re-gas.
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#6
From the Lexia BSI Activation menu I tried to activate the 'Air conditioning compressor control'. According to the instructions I should be able to hear a clicking sound, but nothing was clicking.

Is the AC compressor clutch driven by a relay on the BSI itself?

BSI Information (from Lexia):
  • PSA reference: 9657999380
  • Additional number: 9657999680 (the same number as on the label on the BSI unit)
  • Supplier: Siemens
  • Software version: 22.10
  • Software reference: 624394
BSI label:
  • BSI E01-00 
  • HG
  • 9657999380
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#7
Could the pressure switch be dodgy?

Check all of the basic things first no matter what the diagnostics are saying.

Take a look on youtube for air con fault finding, that may help you.


.
My vehicle .... 2006 (m59) Berlingo Multispace Desire - 1.6 HDI 92 
Reply
#8
I found the right circuit diagram via SEDRE.

I also had Lexia connected again, this time I typed the 5-digit RPO instead of the four last digits. I don't know if it was of any significance, but this time I was able to activate the AC compressor clutch from Lexia.

I analyzed the circuit diagram and I think this is the data/signal flow: 
  1. The AC push-button sends a signal via wire 8053 to the instrument group (0004)
  2. From the instrument group the signal is sent via the 'VAN comfort' bus (9004D, 9005D) to the BSI 
  3. The BSI sends feed-back via wire 8057 to the green lamp in the AC push-button
  4. The BSI should now send a signal to the ECU via the CAN bus (9000A, 9001A) and ask for permission to engage the AC compressor clutch
  5. The ECU should then check the engine conditions (rpm, vehicle speed, cooling system temperature) and send authorization signal back to the BSI via the CAN bus (9000A, 9001A)
  6. When the BSI gets the permission, it activates the AC compressor clutch via wire 8060
Items 1-3 are tested okay, and item 6 is also okay (i can activate the AC via Lexia)

Item 4 thus seems to be the problem, as if the BSI waits for some other condition to be fulfilled. And yes indeed, there is a signal (wire 8072) from the cabin blower control to the BSI indicating if the blower is running or not. The blower must be running before the AC cuts in.

I tried to wiggle the blower control knob while it was in position 1, and I was able to get the AC compressor to cut in. It stopped again in positions 2-4.

Problem found, and now I have to look for a new cabin blower control.

Tanks for the input in the thread.
Reply
#9
Your fault finding is excellent, well done.

Is it the control knob switch of the resister pack that is the problem?


.
My vehicle .... 2006 (m59) Berlingo Multispace Desire - 1.6 HDI 92 
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