[KPires]

Need some help.

Vents are only blowing warm air as the ac compressor is not engaging on my 2011 550.

I've hooked up a gauge to low pressure line and it's at 60psi so it has pressure.

My next step to avoid the worst is replace the pressure sensor.

Any other ideas?

Does the ac compressor have a relay, I can't seem to locate it.

[Hoa]

If you scan with a BMW dedicated software, it will tell you why it won't engage. There is a high chance you are low on refrigerant. There is a leak somewhere. Best to find out is to add dye, add refrigerant and see where it leaks from. Most common place is the condenser.

[KPires]

Originally Posted by Hoa

If you scan with a BMW dedicated software, it will tell you why it won't engage. There is a high chance you are low on refrigerant. There is a leak somewhere. Best to find out is to add dye, add refrigerant and see where it leaks from. Most common place is the condenser.

I checked the pressure and it was at 60psi?

[Hoa]

Originally Posted by KPires

I checked the pressure and it was at 60psi?

Is 60psi for low or high side? If low side, it's too high. If for high, it's too low. Low side pressure is between 30-40 psi and your high side pressure is between 150-175 psi. This varies depending on ambient temperature and humidity

[KPires]

Originally Posted by Hoa

Is 60psi for low or high side? If low side, it's too high. If for high, it's too low. Low side pressure is between 30-40 psi and your high side pressure is between 150-175 psi. This varies depending on ambient temperature and humidity

It's was for the low side which is too high… could that cause compressor to stop you think?

[Hoa]

Originally Posted by KPires

It's was for the low side which is too high… could that cause compressor to stop you think?

I am not aware if it have a sensor to do that. I know it only have a sensor to detect low psi and would not engage the compressor to protect it.

I strongly recommend getting it scanned with a BMW software like ISTA or BimmerLink to see what the issue is. We are guessing in the dark. Also check the high side.

[Surly73]

Originally Posted by Hoa

Is 60psi for low or high side? If low side, it's too high. If for high, it's too low. Low side pressure is between 30-40 psi and your high side pressure is between 150-175 psi. This varies depending on ambient temperature and humidity

Not arguing with you that they should scan codes etc... but if the compressor won't run, then high and low will equalize. Your quoted nominal pressures are for a system with the compressor running.

I believe what they're trying to communicate is that the system at rest has 60psi so all the refrigerant is not gone. A few years ago I had a leaking condenser replaced under warranty. By weight I had almost no refrigerant left and my compressor still ran, the system just didn't perform very well. I would think that 60psi system off would still allow it to attempt to start.

OP - scan some codes as a starting point. Use ISTA or something else BMW specific, a generic OBD2 code reader isn't going to pull codes from IHKA. I can't offer specific advice on relays or fuses to check, but maybe some can. Check the wiring which connects to the compressor as well.