Date: October 1-7, 2021
Replace Solenoid Valve of Air Conditioner Compressor
This year, the F18 BMW 5PowerN20 engine often has the fault that the compressor does not cool after the cold car starts. It needs to press the AC key repeatedly and work only a few minutes later. It is a common fault on the Internet, and it is likely to be a solenoid valve problem. So online bought solenoid valves, 3 bottles of snow seeds and compressor oil, as well as improved air conditioning pipe brackets.
1, the mode of operation, originally proposed two directions: plan A: remove the intake manifold and engine computer, do not move the air conditioning compressor, replace the solenoid valve in the engine cabin; plan B: remove the air conditioning compressor to replace the solenoid valve. After comprehensive consideration and reference to online information, I decided to adopt set B scheme to remove the compressor and replace the solenoid valve; maintenance shops also do the same.
2. Operation preparation: what I removed this time: the empty filter box, the first section of the inlet and the vacuum tube of the inlet, because I use an angle grinder to grind the screw head, the small space is very dangerous, be very careful, and remove several sensor plugs around it; of course, the generator belt must be removed and the tension pulley must be stuck, otherwise it will block a compressor screw.
3. When removing the compressor, you must remember to completely empty the refrigerant first. Use the T30 plum blossom inner hexagon to remove the air conditioning pipe mouth screw, the high pressure pipe mouth screw is loosened smoothly, but loosening the low pressure pipe mouth screw is difficult, and the screw head is twisted! It doesn’t feel good, the space in this place is very limited, and the compressor is a valuable accessory. Take the angle grinder, make a slot in the screw head and twist it with a screwdriver. Unfortunately, the screw head is broken into a semicircle, so the screw head is carefully smoothed with the angle grinder, and the low-pressure pipe mouth is finally loosened. Because there is no suitable E12 plum blossom sleeve, I waited 2 days to remove the compressor installation bolt, this bolt is steel, not aluminum, can be reused.
4. I thought that after taking out the compressor, I could easily get off the rusty screw with a large broken end. I first used an angle grinder to grind out 2 planes, twisted with a wrench, and even broke the screw! The so-called screw breaking tool on the Internet is also useless, because the ordinary twist bit can not drill the screw body at all. This is so rusty! It seems that we have to find a professional, so take the compressor to the machined shop, destroy and take out the broken screw, and make the sleeve screw again. I also found a screw of the same type in the old screw pile in the repair shop. I don’t have to buy another screw (it’s too late).
5, go home, replace the new solenoid valve, the inside of each pipe joint of the compressor is very clean, make sure there is no damage to the compressor. This is Valeo compressor, made in China, this time the disassembly of pipes and solenoid valves, basically no leakage of refrigerant oil. Solenoid valve online shopping, it is best to provide the frame number, because to F18 matching compressor manufacturers also have Denso, the two compressor solenoid valves are not universal.
6. Install the compressor, replace the improved air-conditioning pipe bracket purchased online, and also replace the sealing ring of high and low pressure pipe mouth, which can be easily installed with cold medium oil. The back is to restore the sensor plugs, generator belts, trachea and so on. Because of the need for leak detection and vacuum, I had to go to the air-conditioning store outside the next day to pay the man-hour fee.
7. when you get to the air-conditioning store, it takes about 40 minutes to press and detect the leak. the master said that if there is no slow leakage in the system and no oil leakage in the disassembly and assembly compressor, there is no need to add refrigerant oil this time. Vacuum, drive AC, add 2 bottles of snow seed from the low pressure tube, although the car nameplate indicates the amount of snow seed 850g, but the actual dosage is based on the refrigeration effect and system pressure, after 2 bottles of 600g snow seed is added, the apparent pressure reaches 2kg/cm ², and the air outlet temperature can reach 3.2C, so it can be done.
Conclusion: low-pressure pipe due to low temperature, there is a lot of condensed water, the pipe mouth fixed screw is easy to rust, the screw can not be twisted off, this hidden danger will go wrong sooner or later, do-it-yourself friends should be prepared. Observe for a period of time to see the effect, hope that the system does not leak.