After searching the forums for a post on how to repair my air conditioning, I really didn't find anything in detail, so I just jumped in and did it myself. I have a 1999.5 Jetta with manual trans. The whole process took me about 5 hours, including a couple mistakes. By reading this post you can probably do it in about 3 hours with no complications. The symptoms I was having initially were poor cooling (compressor was engaged), then severe noise like a bucket of bolts, and eventually total loss of function, after a couple more days. The a/c button on the dash was lighting up, but there was no voltage at the wiring harness. There was little charge left in the system. I diagnosed this as compressor failure and a leak at the shaft seal, after inspecting all the hoses and the condenser in front of the radiator.
I ordered the following parts from Impex: AC Expansion Valve COST: $35.71 2. AC Receiver Drier COST: $69.97 3. AC Compressor
COST: $300.00. I'm not sure the expansion valve was bad, but I didn't want to take any chances of having to order more parts. In doing this job, I discovered that the receiver-drier is supposed to be replaced every 3 years, even if the system seems to be working OK. The receiver drier removes impurities and moisture and must be replaced whenever the system is open.
Next, I ordered 6 cans Enviro-Safe Industrial 12a for $45.00 from autorefrigerants.com. It turns out I only needed 2 cans to do this job, about 10 ozs., which is the equivalent of 32 ozs or R-134. The system calls for 750 g or 26.8 ozs. R-134a, The enviro-safe is a hydrocarbon, not chloro-or fluorocarbon. I purchased O-rings for the system, oil charge with R-134, and a gauge/connector at Advance Auto Parts for about $20.00 for all.
Now, on to the job. You will need the following tools: 17mm socket, phillips screwdriver, pry bar, adjustable crescent wrench, 4, 5, and 6mm hex keys, possibly wire cutters, solder and heat shrink tubing. If there is charge in the system, the environment will thank you if you take it to a shop to have the refrigerant recovered. Mine had already leaked out.
First, put the car up on jack stands in the front and remove the passenger side wheel, skid plate, and side skirt. You will see the compressor right at the bottom of the front of the engine:
Remove the serpentine belt by using a crescent wrench on the tensioner and just slip the belt off. Put it up out of the way and try not to let it come of the other pulleys.
Next, if there is charge in the system, make sure it's evacuated and then use the 6mm hex key to remove the refrigerant lines from the rear:
Place the hoses down on the ground so that any contaminated oil can drip out. I placed a wrench on them to hold them down. There was some oil, but not too much. You may see pieces of slivered metal in the oil. I also ran a bit of the new refrigerant through the suction port to flush out at least that line. If you use the enviro-safe refrigerant, you don't have to feel guilty about this.
Next, remove the electrical connector and use the 17mm socket to loosen the 2 bolts holding the compressor on (11:00 and 2:00):
Mine was in very tight and took some prying to get out, even after the bolts were removed. Just make sure not to drop it on your head. Save the bolts to re-use.
Next, remove the receiver-drier. This is located on the passenger side of the radiator. Mine was labeled "Parker" and "Made in USA!"
In order to remove it easily, remove the screw holding the refrigerant line on top of where you will be working:
Next, gently move the refrigerant line from which you just removed the screw. It's flexible enough to move without breaking if you are careful. Then use the 6mm hex key to remove the refrigerant line from the top of the receiver drier, seen in pic above. Get under the car and use the 6mm hex to remove the refrigerant line from the bottom. The top line was on very tight and connects to the condensor, so be very careful not to break it. Finally, use the 5 mm hex key to remove the hex bolt retaining the receiver-drier. You can then slip 1/2 of the holder out of a slot toward the front of the car.
Install the new receiver in the openingsame as the one you removed. The receiver/dryer goes in welded side up, at least in the replacement units...just check as the bottom line has three holes needed and the top just two:
slide the holder back together and reinstall the 5mm hex nut, but do not fully tighten yet. Remove the old o-rings from the refrigerant lines and replace with the appropriate size. Slide the receiver-drier up in the holder and align the opening with the connection to the condenser, then reinstall the 6mm hex nut into the top thread. Once it starts getting hard to turn, go ahead and fully tighten the retaining band with the 5mm hex, after you make sure it's up high enough in the slot. This will prevent you from torquing (and breaking) the condenser. The 6mm hex must be fully tightened so there is no gap between the refrigerant line and the top of the receiver. Next, reinstall the bottom refrigerant line after you replace the o-ring. You are ready to install the new compressor.
Locate the 17mm bolts and install the new compressor using them.
Reinstall the belt making sure it's on all the pulleys correctly. Next remove the factory plugs seen in the pic above using the 6mm hex. Replace the o-rings on the refrigerant lines and then install to the back of the compressor. Make sure there is a nice tight fit to the machined metal surface. In my car, the plug was a different style, an so I had to reuse the connector from the old compressor. If you have to do this, I recommend soldering the wires and then using heat shrink tubing:
It should look like this when you are done:
Slide the wire harness into its metal holder and then connect it.
Next, you may replace the expansion valve. It is located on the firewall in front of the passenger seat, and covered with a plastic insulator. The insulator unsnaps from the passenger side and has a hinge on the driver side. Here is a pic with the insulator already removed:
Using the 5mm hex, remove the first bolt holding the aluminum retaining clip seen in the pic above. Carefully slide the hoses out of the valve and replace the o-rings.
Use the 4mm hex to remove the other two hex nuts and then slide the valve off. Replace the o-rings. Here is the old and the new valve with the 4mm hex bolts:
Reinstall the new valve using the 4mm hexes first, then reinstall the aluminum retaining clip and the refrigerant lines. Replace the insulator. It only fits one way. Now, you are ready to test the system. Follow the directions with your gauge and install it to a can of oil charge. With the car off, snap the quick-connect onto the low side refrigerant line, located right near the receiver-drier. It has a black cap on it:
Open the valve on the can and let a little refrigerant into the system, then close the valve on the can. Note the pressure reading and wait 5 minutes. Make sure the pressure doesn't drop, although it may go up. If it goes down, you have a leak. Luckily, I did not. If there are no leaks, allow the oil charge into the system by turning the can upside-down. Now, get another can of refrigerant, pierce the top, and install to the lowside connector. Start the car and turn on the AC.
Open the can of ec-12a refrigerant and allow it into the system, slowly. Turn the can upside down, but not all at once - a little bit at a time. It will take the whole can. Check your pressure. Mine was about 35 psi.
It will probably take about another 3-4 ozs from a second can. DO NOT use the whole second can. It is too much.
Get inside the car and check your temp at the outlet on recirc mode. It should look like this:
Sweet! Now I have a/c again. And, it's colder than before using the EC-12a refrigerant. Good Luck.