2012 berlingo 1.6 aircon issue

[Jayp]

Good afternoon everyone,
I own a 2012 berlingo and noticed my aircon stopped working. I plugged my Autel to the car to see if it had any stored codes and found the following code on both the bsi and the aircon control unit.

C995 - fault in the aircon compressor variable capacity piloting control circuit

And on the engine control unit I’ve got a CAN code

U118 - intersystems CAN

Upon further inspection l identified the wires from the compressor valve to the engine fuse box unit and realised they were both completely split right before the plug on the fuse box side. Assuming it was caused by rats I repaired both wires, and tested the resistance using a multimeter to assure the job was done right. I thought for sure the fault would’ve gone away after that but it hasn’t, I can’t clear it. Since then I’ve replaced both the compressor since it was the still original one and the car is over 10 years old and the engine fuse box unit (2nd hand). No luck yet.

I’ve got the aircon gauge plugged in the car and the high pressure line is nearly at 350 psi, I’m not sure if that’s because the valve isn’t operating or if I have any other issues within the aircon system. Like the TX valve or something. Whenever I turn the car on the radiator fan comes on at full speed, I’m assuming it’s due to the high pressure reading.

Has anyone experienced anything like this, or is able to lead my down the right path? I’ve also tried a bsi reset but no luck. Appreciate it in advance.

 

[David S]

If it's stone cold and you turn on and find the fan goes to full speed and the temperature gauge reads high as though it's overheating, you may need to replace the coolant temp sensor on the outlet tank on the head. If there is no low speed fan, it may need the resistor unit for the engine cooling fan. It's on the radiator support. Both those faults could be inhibiting the AC.
A new compressor should rule out a problem with the control solenoid in the compressor.
It will have a high-low switch to shut the AC down in case of too much pressure.

 

[ozVTR]

This isn't making a lot of sense to me. If the "aircon stopped working" then the compressor wouldn't be compressing the refrigerant and the high side wouldn't get up to 350psi.
Or are you saying the 'static' pressure (without the compressor running) is 350psi? How the heck do you get the static pressure up to 350psi??? Was it filled from a BOC truck?
IF the compressor is running AND the high side is going up to 350psi BUT you have no cold air, then you have a blockage in the system.
BUT, I find it hard to believe that, coincidently, you get a blockage in the system AND rodents eat the wiring AND the over pressure cut out is not working!!
The high side over pressure cut out (typically) is 'about' 250psi (maybe a bit more). So that would mean the static pressure is 350psi and the compressor clutch is locked out. Again how did the static pressure get up to 350psi? Over pressure lock out does not throw up a diagnostic code, it's not considered a fault. However it will show up as "not permitted" in the engine ECU stats.
Ok, some of the new compressors don't have a clutch. But I would have thought the 'fail safe' for the regulator valve was full bypass and the compressor is not compressing the refrigerant??
So let's assume the valve controller is faulty and this causes the compressor to run at full pressure. Why doesn't the interior air get cold? A blockage in the system? Now we are back to two simultaneous failure events (the controller and a blockage). I don't think so.
Static, and not having run for a while the high and low sides should both read about 90-100psi, dependent on the ambient temp.
What is the 'low side' pressure doing?
Does the compressor have a clutch?
Yes, if the system detects high pressure it will run the radiator/condenser fan at full speed irrespective of whether the aircon is selected or not.
First up I believe the system is over charged...but 350psi? WOW! As I said, I'm not making a lot of sense out of this. At least from the info given. As Johnny 5 would say "need more input".

 

[Jayp]

This isn't making a lot of sense to me. If the "aircon stopped working" then the compressor wouldn't be compressing the refrigerant and the high side wouldn't get up to 350psi.
Or are you saying the 'static' pressure (without the compressor running) is 350psi? How the heck do you get the static pressure up to 350psi??? Was it filled from a BOC truck?
IF the compressor is running AND the high side is going up to 350psi BUT you have no cold air, then you have a blockage in the system.
BUT, I find it hard to believe that, coincidently, you get a blockage in the system AND rodents eat the wiring AND the over pressure cut out is not working!!
The high side over pressure cut out (typically) is 'about' 250psi (maybe a bit more). So that would mean the static pressure is 350psi and the compressor clutch is locked out. Again how did the static pressure get up to 350psi? Over pressure lock out does not throw up a diagnostic code, it's not considered a fault. However it will show up as "not permitted" in the engine ECU stats.
Ok, some of the new compressors don't have a clutch. But I would have thought the 'fail safe' for the regulator valve was full bypass and the compressor is not compressing the refrigerant??
So let's assume the valve controller is faulty and this causes the compressor to run at full pressure. Why doesn't the interior air get cold? A blockage in the system? Now we are back to two simultaneous failure events (the controller and a blockage). I don't think so.
Static, and not having run for a while the high and low sides should both read about 90-100psi, dependent on the ambient temp.
What is the 'low side' pressure doing?
Does the compressor have a clutch?
Yes, if the system detects high pressure it will run the radiator/condenser fan at full speed irrespective of whether the aircon is selected or not.
First up I believe the system is over charged...but 350psi? WOW! As I said, I'm not making a lot of sense out of this. At least from the info given. As Johnny 5 would say "need more input".

Tell me about it, it’s a weird one for sure…. 350 psi is the pressure I’m getting on the high side while the compressor is running. Low goes down to around 25 psi. System is not overcharged as I’ve recharged with the right amount during the weekend. Since the air is cooling i probably have a blockage somewhere in the system, I’ll pull it after in the next couple days and see if I can find anything. The split wires had me thinking it was an electrical issue, but I think im going down the right path now. I’ll keep you posted on what I find. Really appreciate the input.

 

[Jayp]

Do you think a faulty expansion valve could be the cause?

 

[ozVTR]

Would you say the air coming out of the vents is very cold? Or just cool?
I need to know the static pressure of the system. This will tell me if it's over charged or not.
Yes a stuck Tx valve will cause this...but you really don't want it to be the Tx valve! They usually require the removal of the entire dash to replace!! If you are lucky, some can be removed through the fire wall.
The "high side" service port is typically between the receiver/dryer and the Tx valve. Blockages would usually occur in the condenser or the receiver/dryer. But we have high pressure on the high side. That just leaves a blockage in the ("liquid") line or the Tx valve and it's very unlikely to be a blockage in the line.
So it seems to come down to being either over charged or the Tx valve.
I hope for your sake the system is just over charged. But as I said, the static pressures will tell us.

 

[David S]

The expansion valve can apparently be removed from the engine bay side in a B9 Berlingo/Partner. This is for a Partner.