BMW Repair: AC PROBLEM, two inlets, compressor clutch

Question

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Followup To

Question -
HI SLATER

i HAVE A 2002 X5 3.0I WITH 75000 MILE MY AC DON'T WORK PROPERLY. i HAVE DONE THE AC SERVICE WHERE WE RECYCLE AND CHARGE THE SYSTEM AGAIN. iT LOOK LIKE IT WORK FINE BECAUSE THE HIGH SIDE READS 250 PSI AND THE LOW SIDE IS 30 PSI THE COMPRESSOR IS ALLWAYS WORKING AND i CHECKED THE DOOR AND IT LOOKS LIKE THEY WORK FINE TOO THE PROBLEM IS THAT THERE IS LITTLE COOL AIR BLOWING AT THE MAX SETTING (THE BLOWER WORKS GOOD TOO)AND LESS COOL AIR ON THE PASSENGER SIDE. THERE IS CONDENSION TOO BECAUSE WATER IS DRAINING ALSO i SEE THAT THE LOW SIDE PIPE DOSN'T GET COLD. WHAT DO YOU THINK IT MIGHT BE? COULD IT BE THE MODULE HOW DO YOU CHECK THAT OR OTHER SENSOR? THANKS FOR YOU HELP AND TIME.

Answer -
ART the high side pressure seems a little high for my local temps but you didn't mention ambient temp. It is within range. This may sound strange but uneven duct temps usually means an Undercharged A/C system. Also if you do not have condensation on the low side hoses then there is something arye in the A/C system (low charge, little refridgerant movement, or poor air flow through Condenser or Evaporator)and I would almost completely rule out the module if the Compressor clutch is engaged. Please check the Auxiliary electric pusher fan operation, I Replace a lot of faulty fan units. Need to remove bumper skin if it turns out faulty. Not to scare you but many fan units on your model several years ago would short internally and cause fire. Please don't over look this. Make sure the system is properly charged. I don't know what you mean by "checking the door and looks fine" What door are you refering to. Check the Auxiliary water valve toward the firewall. Valve will have electrical connection and at least three coolant hoses (two inlets and one outlet) temporarily clamp off the inlet hoses to the heater core to restrict coolant flow. If the duct temp improves you found your culprit. Not a high possibility of a water valve because you don't have condensation on low side hoses. Hope this helps- let me know
-Evan


HI Evan,

 How are you? sorry to bother you again but this system is giving me a headache. The ambient temp is reading what the news is calling and the condenser fan works fine, plug the water valve but same temp coming out in the cabin. where is the Auxiliary electric pusher fan? is that the condeser fan? I was going to replace the expansion valve but someone told me that the low pipe dosent condese on those bmw x5 that the system probably needs to be reprogram. The high pipe after the conection on the expansion going to the condenser is cold and the low pipe is warm before and after the expansion. What should the psi be on the high and low? What I mean about the door is the one that divides the heater core to get hot air and the evaporator for cold air and where is the step motor located? Thanks again for your help have a good day.

Answer
Art, The condenser fan is the same as Auxiliary fan, just different terminology. I didn't understand the ambient temp statement. What is the ambient temp? I don't know where you live or what news you watch. I am also a little baffled by low pipe/high pipe references. The suction line from the evaporator to the compressor should have condensation (sweating) on it and be cold to the touch. The discharge line from the compressor to the condenser should be very hot to the touch (be careful). The liquid line from the condenser to the Expansion valve/evaporator should be warm to the touch. Your Reciever/Dryer is a canister insert on the side of you condenser (easy to replace).Remember that the X5 only takes one pound of R-134A, it is an undersized system for a big cabin area. Remember that Auxiliary fan must run when the A/C is on. Your pressures look to me like the system is overcharged but I don't know your ambient temp or relative humidity when you are taking your pressure readings. Please provide these figures. I don't believe that your module is at fault because the mechanical A/C system doesn't have the proper characteristics of a normal system. The Blend door is the mechanical wheel between the center vents. It is good that you checked this operation. The stepper motors control various distribution doors for the Climate control system and there are many. Not your area of consern at the moment. Please verify that the system has the correct amount of R-134A by evacuating and recharging the system to 1.00Lbs. Place system under vacuum for 1/2 hour and stop vacuum and make sure the system holds the vacuum. The X5 system is very sensitive to over/under charging because the capacity is so small. I would remove and replace the Drier cartridge on the condenser and inspect for metal shavings from the compressor while you have the system evacuated. If you want to replace the Expansion Valve go ahead. When did the trouble with you A/C begin? Let me know what you find and tell me left, center, and right vent temp with system running at 1500rpm after 3 minutes.
-Evan