Car: 2009 R56 S. Air conditioning sometimes blows cool air and sometimes not. I use BimmerLink to read codes. I had a friend check low side pressure and it seems to be good. I'm reading high side off of BimmerLink. During all of the following tests, the compressor stays on. I was having it short cycle some before I added a little coolant. When I'm stopped the engine fan seems to ramp up and the high side pressure ramps up to between 200-300 and the air comes out cool. When i start moving the fan speed (as read on BimmerLink) slows down to below 50% and the pressure drops to around 150 or less. (See attached graphs)



Also, the fan does not run after the car shuts off any time. I have attached a pic of the fuse box. When i take both R3 and R4 relays out and start the car with the A/C full, there is no fan. If I insert the relay into R4, I get high speed fan. If I insert a relay into R3, I get the fan in low speed.

Any ideas?

Thanks

 

What are your static pressures (high side/low side) with the engine shut off?

Do you have automatic or manual climate control system?

"I was having it short cycle some before I added a little coolant." Just to be accurate ... coolant goes in the cooling system; refrigerant goes in the HVAC system. Did you add coolant or refrigerant? How much refrigerant did you add? Refrigerant should be 1.08 lbs exactly. Too much or too little will cause problems!

BMW/MINI uses different relays compared to other manufacturers, and they are not interchangeable. There's the Type A relay and the Type B. See pics. Make sure you have the correct relay part number installed in each location.



Also, measure the refrigerant temp at the inlet of the condenser with a temp gun or thermal imager and compare it with the outlet temp. The outlet temp should be 8-10 degrees cooler.

 

Thank you very much for the reply. I did buy a new relay and it is not OEM. It is however the correct pin configuration. I had a friend with a pressure gauge add ‘refrigerant’, not coolant. I’ll have to get my own gauge and do some more checking. I’ll reply when I get more data. Thanks again.

 

Have you figured out your issue? My Mini started doing the same thing two day's ago...

 

I have not. I'm on vacation for a while. With all my research, I think I may be over my head and may just bite the bullet and take it in to a shop. It seems to be sort of working. Maybe I just don't have the exact amount of refrigerant...