DIY - MKIV A/C Compressor, TXV, and Dryer removal / replacement
The following procedure will guide you through the removal and replacement of the aforementioned components. This will require a discharge and a recharge of the refrigerant and oil. If you have not done so already, it is important that you read the following documents below:
When you purchase the O-rings from the dealer, make SURE that you have the right sizes and thicknesses. There are many, many different O-rings, so compare the sizes to each other, to the pictures below, and to your replacement parts.
Please be careful when performing this procedure. You WILL need some mechanical aptitude, so read through the whole thing before trying it. I can't be held responsible if I have made a mistake in the following steps.
-PAG oil (1 quart should be sufficient)
-Refrigerant ( more then 30 oz)
-New / Reman Compressor: VR6 engines use a 7 spline pulley. 2.0, 1.8t, and TDI all use a 6 spline pulley, so make sure you check your part number to the reman one.
-Torx 35 screwdriver
-Torx 25 screwdriver
-Jack and Jackstands
-M8 bolt (for the belt tensioner)
-6 mm hex wrench
-5 mm hex wrench
-4 mm hex wrench
-prybar or lever
-plugs or tape to cover open lines
Removing the Refrigerant
1. In preparation for removing the refrigerant, remove the passenger's side engine cover by performing steps 1-3 of the Spark Plug Removal DIY.
2. Remove the caps on the high pressure and low pressure ports.
3. Turn off the A/C, and evacuate the refrigerant by whatever legal means you have at your disposal. Quite often, you will get some sort of credit from the mechanic who evacuates the refrigerant.
4. With no refrigerant in the system, you will want to cover up the A/C button so you do not accidentially turn it on.
Removing the necessary components
5. Raise the front of the vehicle using your jack and jackstands.
6. Remove the splash guard from under the vehicle with a Torx-25 screwdriver.
7. Move the lock carrier to the "Service Position" by using this Lock Carrier DIY Guide. You do not need to do the Extreme version, you only need a few inches of clearance.
8. Remove the passenger's side splash shield by unscrewing the two washer nuts shown below, and the single Torx 25 screw indicated. The splash shield should then slide down.
9. Remove the serpentine belt by performing steps 3 and 4 of the Belt Tensioner Removal DIY. Hang it up to make sure you put it on the same way you took it off.
10. Remove the A/C Compressor as follows:
a) Slide the clutch coil connector out of its holder by pulling it straight towards you.
b) Once loose, disconnect the plug from the socket.
c) Remove the lower compressor hose by unscrewing the lock bolt with a 6mm hex wrench. WARNING:The refrigerant system is still pressurized!!! Be VERY careful disconnecting this line, as refrigerant and oil will spray from the fitting when disconnected.
d) Remove the upper compressor hose by unscrewing the lock bolt with a 6mm hex wrench. Due to room constraints, you may not be able to disconnect this hose from the compressor until the compressor is removed from its mounting bolts.
e) Remove the lower 16mm bolt holding the compressor onto the mounting frame.
f) Unscrew the upper 16mm bolt holding the compressor onto the mounting frame. You will note that the bolt will not come out all the way, but it will *barely* clear the frame so you can remove the compressor.
g) Use a lever of some sort to pry the compressor away from the frame. Slide it to the side to get it out.
h) Cover up the ends of the hoses with a plug or tape to prevent debris from entering the lines.
11. Remove the Dryer/Receiver as follows:
a) Remove the banjo clamp holding the dryer in place with a 5 mm hex wrench. The bolt will come out all the way, and one half of the clamp will seperate from the other half.
b) Remove the top and bottom hoses from the dryer with a 6 mm hex wrench. Note: The top and bottom bolts are different sizes, so make SURE you label them properly!
c) Once the dryer is free, slide it out the clamp from the top.
d) Cover up the ends of the hoses with a plug or tape to prevent debris from entering the lines.
12. Remove the Thermal Expansion Valve (TXV) as follows:
a) Unclip the black plastic housing surrounding the TXV. The latch is on the passenger's side, and rather difficult to get to.
b) Here is a photo of the housing removed so you can see the latch. The black tab points down.
c) Remove the engine side coupling clamp with a 5 mm hex head. This will allow you to remove the hoses from the TXV.
d) Remove the top and bottom 4 mm hex head bolts that connect the TXV to the evaporator side coupling clamp.
e) You can now remove the TXV. Pull straight out on it to slide it off the evaporator lines.
f) Cover up both ends (4 lines) of the TXV connectors with a plug or tape to prevent debris from entering the lines.
Testing / Cleaning your compressor
13. If you have purchased a used or remanufactured compressor, you will want to test the functionality of the compressor as follows:
a) The outer pulley should rotate freely, with no interference or motion on the inner pulley.
b) Rotate the inner pulley counterclockwise ONLY. Make sure it is not bound; it may be difficult to turn, but it should turn freely.
c) Test the coil resistance by connecting an Ohmmeter across the two pins on the connector. From 3 to 5 ohms is acceptable.
d) Energize the coil by applying a +12 V signal to pin 1 (Green wire) and the ground to pin 2 (Brown Wire). This will connect the outer and inner pulley. Make sure they both rotate together when the coil is energized.
14. You will also want to flush the compressor with PAG oil to clean out any dirt or debris. Do this as follows:
a) Locate a measuring device of some sort. You want to be able to measure out oil in 1 ounce parts. I found that using my own Shot Glass would be more acceptable then using my nice All-Clad measuring cups. For reference, 1/8 of a cup is 1 ounce.
b) Remove the compressor fill plug with a 17 mm socket. Then turn the compressor over and drain any residual oil.
c) Using your measuring glass, add 2 ounces of PAG oil into the fill hole for the compressor.
d) Re-install the 17 mm plug, and tilt the compressor on its pulley. Remove the tape covering the compressor ports. Note the labeling on the compressor, and add 2 ounces of PAG oil to the suction side of the compressor.
e) With an electric drill, turn the compressor over counter-clockwise while covering the discharge port with a rag. Do this slowly at first to lubricate the pistons, and then faster until oil squirts out the discharge valve.
f) The oil that squirts out will give you an indication of the cleanliness of the compressor. Repeat steps a-e until the oil is clean.
15. Once you are satisfied with your flush, remove the compressor fill plug and drain any oil inside. Add 4.6 +/- .5 ounces of PAG oil to the compressor. This will provide lubrication for the entire A/C system.
Flushing the rest of the A/C system
16. To clean out the rest of the system, you will want to backflush the condenser and the evaporator with compressed air, and then nitrogen. Start by connecting your air source to the downstream side.
17. Holding a rag on the upstream side to capture any debris or oil, turn on your compressed air supply. Do not apply more then 40 PSI to the evaporator or condenser.
18. After you are satisfied you have collected most of the oil and debris, use your nitrogen supply to backflush the evaporator and condenser.
Installing A/C components
19. Starting with the TXV, lightly lubricate the evaporator side O-rings with PAG oil. Then install them on the evaporator connections.
20. Slide the evaporator side coupling clamp over the lines, and then press the TXV into place. Reinstall the two 4 mm hex head bolts and torque to 8 Nm or until tight.
21. Lightly lubricate the engine side TXV O-rings with PAG oil, and slide them on the appropriate lines. Slide the engine side coupling clamp over the lines, and fit the lines into the TXV.
22. Install the 5 mm hex head bolt through the coupling clamp into the TXV. Tighten the 5 mm hex head bolt to 8 Nm or until tight.
23. Reinstall the black plastic cover over the TXV.
24. Slide the top bolt into the compressor, and fit the compressor into the frame. Then install the bottom bolt.
25. When the bottom bolt is finger tight, push the compressor up so that you can install the top bolt. This parts really, really sucks.
26. When both bolts are finger tight, torque the bolts to 45 Nm (33 ft-lbs).
27. Lightly lubricate the compressor O-rings (part numbers: 7H0 820 898-14.3x2.4 and 8E0 260 749-10.8x1.82) with PAG oil and install them onto the compressor hoses. Install the hoses into the compressor and torque the 6 mm hex head bolts to 20 Nm (15 ft-lbs).
28. Finally, install the dryer. Remove the caps and install with the label so you can read it. Lubricate the two O-rings (Part #s: 8E0 260 749-10.8x1.82) for the dryer with PAG oil, and then slide the hoses into the dryer. *Lightly* tighten the 6 mm bolts.
29. Install the banjo clamp around the dryer, and tighten the 5 mm hex head bolt until tight.
30. Now, torque the 6 mm hex head bolts on the dryer to 15 Nm (11 ft-lbs) or until tight. You do not want to torque these bolts until the dryer is fixed in the clamp.
Leak testing the system
31. Connect your manifold to the low and high pressure service ports. Connect the charging hose to your nitrogen supply. Make sure the low pressure service valve is closed, and then open the high pressure service valve. Then, pressurize the system to 200 PSI with nitrogen.
32. Close the nitrogen supply and disconnect the manifold from the low and high pressure service ports. Wait one hour to ensure the system is still sealed.
33. In the meantime, find some things to do. You can.....re-lubricate your serpentine belt tensioner. (Thanks, Gary!) Then, install the serpentine belt.
34. After your hour wait is up, reconnect the manifold and check the high pressure side. If the pressure is approximately the same as it was, then your system is ready to be charged. Otherwise, you need to check all your fittings for leaks.
35. Now, you can evacuate the system. If you do not have the proper equipment to do this, SKIP this step. You will want to evacuate the system for a minimum of 1 hour. Most vacuum pumps are designed for constant, 100% duty so let it run as long as you want.
36. Once you have evacuated the system, properly charge the system with 26 +/- 1.8 ounces of R-134a. If you are familiar with charging refrigerant, then you can get the compressor to kick on by directly applying +12v to the coil as you did in step 13.d).
Note: At this point, re-test the A/C system to make sure it works. If not, you will need to go back and check something.
37. Return the lock carrier to its proper position.
38. Reinstall the passenger's side splash shield.
39. Reinstall the center splash guard.
40. Lower the front of the vehicle.
41. Reinstall the caps on the service ports.
42. Reinstall the passenger's side engine cover.
Modified by FaelinGL at 12:06 AM 7-10-2007