How to Repair Automotive A/C

Step 2 Expantion Valve and Flushing

If you decide that the A/C system needs to be flushed in order to remove debris and oils you will need to remove the compressor, expansion valve, and the drier. DOT NOT FLUSH THROUGH THESE COMPONENTS. Also if you are retrofitting your system from R-12 you will need to flush out all the old mineral oil as oils tend not to be compatible with each other. Mixing oils or refrigerants will result to what is reffed to as as black death by mechanics.

The pictures below cover the most difficult part which is the get to the expansion valve. Once you have the evaporator out the car you may find it to be very dirty. I cleaned mines in the shower, remember to be really careful not to get water in the pipes which freon runes through. If you already spent all that time getting it out the car its not a bad idea to replace the expantion valve and do the be best you can to wrap it in sum thermo insulation material. I used some packaging material and tape to hold it in place. (Now that I think about it maybe glue would have been a better idea)

The flushing proses I will not cover in detail, but all that you need to do is to spray a A/C flushing compound it the freon pipes. Then wait 20 min and flush it out with shop air. I was fortunate enough to be able to use the shop compressor at my school. If you use a potable one it most likely will not be able to keep up with demand and you will have to wait for the tank to refill.