A common problem on mk5 chassis cars is a bad radiator fan. Standing in front of the car and looking at the engine, the large fan on the right houses the fan control module. The small fan on the left is a plain DC fan with only power/ground connections. Whenever the AC is on and the large fan is running, the small fan should also be running.
The most likely cause of a failed AC fan is sticking contacts (brushes) on the motor. Removing the fan and cleaning the brushes is an easy fix and the repair should last as long as buying a replacement. If you choose to replace the part, the part numbers are below.
If you're having problems with the AC system not working or a 5-10 minute delay in coming on, the most common cause is a failed solenoid control valve on the compressor. Evacuating the system, replacing the control valve and refilling it usually fixes the problem. Warning: evacuating and refilling the system requires professional AC service equipment. Do not empty the system into the atmosphere and try to refill it with the recharge kit from your local parts store. You must draw a vacuum before refilling. Weak AC could also be caused by a condenser/radiator clogged with mud (not likely unless you're off roading!) or blocked with leaves.
If you have any questions about this procedure, please post in this support thread in the VW and Audi TDI forum.
Here is a video showing some detail:
1 large left (driver side) fan: VW# 1k0 959 455 p (BRM engine only)
1 small right (passenger side) fan: VW# 1k0 959 455 dg (BRM engine only)
T25, T30 torx screwdriver/bit
10mm socket and ratchet
Dremel or similar tool
Raise the car, chock the rear wheels, rest the car securely on jack stands, and make sure the car is safe and secure before doing anything else. I use 2 sets of jackstands, minimum - one at the factory jack points to carry the weight of the car and another almost touching the front subframe as a backup. Also see 1000q: wood blocks for another idea of supporting the car. See the TOS Agreement for the full legal disclaimer.
Remove the black plastic splash shield underneath the car. If you have a 2005.5-2007, it has 8x T25 torx on the side (yellow arrows) and 3x T30 torx (white arrows) on the rear subframe. If you have a 2009+ it will have an additional T25 in the front-center. Also, the T30 may have medium threadlocker on them so make sure to firmly press your torx wrench into them to avoid stripping their heads.
Remove the engine cover by pulling it straight up. Place the air filter box to the side. See 1000q: mk5 air filter box removal for details. Do not open the air filter box because this will disturb the gasket and there's no need to open it.
Remove the section of air snorkel that's still attached to the radiator support by removing 2x T25 torx screws. The entire snorkel assembly is shown below.
Unclip the lower intercooler hose by pulling the spring clip halfway out. The hose will wiggle out. Unclip the plug for the fans. The plug has a lock, press the button to release.
You can get a tiny bit more play by removing the 2x T30 screws holding the plastic hardpipe. This will give only a tiny bit of play to the hardpipe but I found it helpful.
Remove the 4x T30 torx screws holding the fan assembly to the radiator. There's enough room to slide it out the bottom but you have to wiggle it out. If you got a little more play on the hardpipe it's easier to get the large fan motor; the area of interference is visible on the left.
There's plenty of access to the T30 screws except for the one by the alternator. I used a 1/4 ratchet with a T30 bit as shown below instead of a T30 screwdriver. (the green wire is for something else I added)
This is what the fan assembly looks like. Unplug the fan and remove the 3x 10mm nuts holding it to the fan assembly. Note the location of the fan assembly screw tabs on the sides.
If you choose to replace the fans, do so now. If you choose to repair, use a dremel to cut the sides of the 3 tabs holding the fan back cover on. The tabs are shaped like a V and clamp the cover in place. You have to cut the V and then use a screwdriver to knock the rear cover off.
It will look like this:
You can now remove the plastic bracket holding the brushes. One of the brushes shown below is stuck in the guide (white arrow) which prevented any contact. No contact = no power. Pull the brushes out and spray brake cleaner in the guide. Clean the brushes and the springs behind them. Put the springs/brushes back and check for proper movement. I also sprayed the rest of the plastic bracket and wiped clean the rest of the fan housing. I would not spray clean the motor assembly because that part has a bearing in it and it might wash the lubrication out. I put a little bit of wd-40 in the brush housing to help lubricate the back-forth motion. This may help prevent sticking in the future.
Check for proper movement and replace the plastic spider and brushes. I resealed the cap using jb-weld as glue. You could also tack weld it, just make sure that it's flat. I hammered on the area near the tabs to ensure that the cap was on straight since there was still a little metal from the V tab remaining. Replacement is the reverse of installation.
If you have any questions on AC system repair on the mk5 Jetta/Golf or Audi A3 TDI, feel free to ask in the myturbodiesel Audi and VW TDI forum or search below: