How do you get a probe into the JN 5 pin connector? The connector only has 3 wires coming out of it, but the wires have some sort of seal at the connector. Also, how do you pull that connector out?
My guess goes to the connector at the compressor, or the compressor itself.
Citroen c3 2008 No AC detected by Lexia
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ozvtr
- Posts: 833
- Joined: 13 Oct 2020, 01:11
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Re: Citroen c3 2008 No AC detected by Lexia
The socket on the BSM has a lug and the plug has a tab, on the side facing the front of the car. You will need a small screw driver to lift the tab off the lug. Or just go to the yellow connector on the compressor if you wish. HOWEVER, if there is no power at the compressor, the next logical step is to check for power at...the BSM!
At the socket in the BSM, pin 5 should be chassis ground. So there should be continuity between pin5 and metal parts of the car. There should be power (12V) between pins 1 and 5 while the AC is supposed to be working.
There are a few things that will stop the AC from working but not show up a clear error.
The radiator fan. A problem with that will stop it. Go into the engine ECU in LEXIA look for faults or do actuator test on fans.
Low refrigerant pressure. This is the usual one that stops the AC from working. Again go into the engine ECU and see if you can see anything about the refrigerant pressure. I am NOT familiar with configurator in LEXIA for the ALL-CAN or facelift C3 (yours), sorry. I only know about the Mk1. However on the Mk1 the info is really helpful...it says "AC inhibited" if there is a fault. Yep, really helpful.
I am beginning to clutch a straws here, there is nothing to go on.
At the socket in the BSM, pin 5 should be chassis ground. So there should be continuity between pin5 and metal parts of the car. There should be power (12V) between pins 1 and 5 while the AC is supposed to be working.
There are a few things that will stop the AC from working but not show up a clear error.
The radiator fan. A problem with that will stop it. Go into the engine ECU in LEXIA look for faults or do actuator test on fans.
Low refrigerant pressure. This is the usual one that stops the AC from working. Again go into the engine ECU and see if you can see anything about the refrigerant pressure. I am NOT familiar with configurator in LEXIA for the ALL-CAN or facelift C3 (yours), sorry. I only know about the Mk1. However on the Mk1 the info is really helpful...it says "AC inhibited" if there is a fault. Yep, really helpful.
I am beginning to clutch a straws here, there is nothing to go on.
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areid
- Posts: 17
- Joined: 02 Jan 2025, 16:02
Re: Citroen c3 2008 No AC detected by Lexia
Just reporting back my latest findings.
Unplugged the connector from the BSM. It has only three cables connected in pins 1 through 3. Pins 4 and 5 are not connected.
Tested with engine off for voltage directly on the pins in the BSM but got nothing. The same with continuity. Tried to turn engine on, but car would not start with the connector unplugged. My probes are to thick to go through the seal in the connector (see pic below) to test conductivity and voltage with engine on.
Am looking for thinner probes to use and try again.
Also tested continuity at the connector itself. Got a response between pins 2 and 3, but pin 1 offered nothing.
I'm avoiding at all costs taking off the wheel and the mud guard to access the compressor. But alas, seems to be the only way left to go.
Perhaps tomorrow I'll have some time to inspect the compressor.
Unplugged the connector from the BSM. It has only three cables connected in pins 1 through 3. Pins 4 and 5 are not connected.
Also tested continuity at the connector itself. Got a response between pins 2 and 3, but pin 1 offered nothing.
I'm avoiding at all costs taking off the wheel and the mud guard to access the compressor. But alas, seems to be the only way left to go.
Perhaps tomorrow I'll have some time to inspect the compressor.
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ozvtr
- Posts: 833
- Joined: 13 Oct 2020, 01:11
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Re: Citroen c3 2008 No AC detected by Lexia
Pin1 will be power for the coil and the other side of the coil will be connected to the body of the compressor.
Pin 5 in the BSM is ground but it's not being used (in this case).
A pin or very thin wire should slip between the wire insulation and the rubber seal with the plug connected to the BSM.
Have you had a look around the engine ECU in LEXIA?
I still have a feeling the compressor is not being commanded on for one reason or another.
Pin 5 in the BSM is ground but it's not being used (in this case).
A pin or very thin wire should slip between the wire insulation and the rubber seal with the plug connected to the BSM.
Have you had a look around the engine ECU in LEXIA?
I still have a feeling the compressor is not being commanded on for one reason or another.
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areid
- Posts: 17
- Joined: 02 Jan 2025, 16:02
Re: Citroen c3 2008 No AC detected by Lexia
It was a hard week and I had no time to tinkle around the car. This weekend I continued trying to sort this puzzle.
After fidgeting with the BSM connector, the A/C sprang back to life, but maintaining its previous behavior. The compressor starts and cycles up for a number of times (sometimes 2, 3 or up to 4 cycles) and then does not engage anymore. Following that tried to see if Lexia could find something, but alas, connection to the ECU is still not possible. That is, Lexia does not see the A/C ECU, but the system works somewhat.
Today was a cold morning so I started the A/C in anti fog mode and warm temperature. The system worked for about 1/2 hour and then turned off, to then start again after 15 minutes or so. During the evening I tested the cold temperature and the compressor engaged and cycled only once, and never again.
So it's back to square one.
My guess is there's something wrong with a cable, either CAN or power cable. Or, there's something wrong with the A/C ECU. Mind you, still haven't checked on the connector to the compressor nor tested it directly with a 12v power supply.
It's either that, or the car is jinxed somehow...
Will try to post further information as soon as I have more.
After fidgeting with the BSM connector, the A/C sprang back to life, but maintaining its previous behavior. The compressor starts and cycles up for a number of times (sometimes 2, 3 or up to 4 cycles) and then does not engage anymore. Following that tried to see if Lexia could find something, but alas, connection to the ECU is still not possible. That is, Lexia does not see the A/C ECU, but the system works somewhat.
Today was a cold morning so I started the A/C in anti fog mode and warm temperature. The system worked for about 1/2 hour and then turned off, to then start again after 15 minutes or so. During the evening I tested the cold temperature and the compressor engaged and cycled only once, and never again.
So it's back to square one.
My guess is there's something wrong with a cable, either CAN or power cable. Or, there's something wrong with the A/C ECU. Mind you, still haven't checked on the connector to the compressor nor tested it directly with a 12v power supply.
It's either that, or the car is jinxed somehow...
Will try to post further information as soon as I have more.
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ozvtr
- Posts: 833
- Joined: 13 Oct 2020, 01:11
- x 230
Re: Citroen c3 2008 No AC detected by Lexia
Have you managed to see if there is power at pin 1 of the BSM?areid wrote: 31 Mar 2025, 21:16 After fidgeting with the BSM connector, the A/C sprang back to life, but maintaining its previous behavior. The compressor starts and cycles up for a number of times (sometimes 2, 3 or up to 4 cycles) and then does not engage anymore.
I would be tempted to remove the BSM and have a look at the solder joint of pin 1. HOWEVER the bl@@dy BSM will be potted (good one PSA). So that's out!
If you can repeat the "fiddle with the yellow connecter and it works for a while" experiment, then you would have to suspect either the connector on the loom or the connector on the BSM.