When I started driving the car one day, I had the A/C on full, but there was hot air coming out of the vents. No other indications or flashing lights indicating trouble. I looked under the hood at the A/C compressor and noticed that the plate that attaches the pulley to the compressor shaft was completely shredded. This is by design, if the compressor freezes the plate shears and the pulley is able to continue to rotate without causing damage to any other components.
I found a compressor on Amazon that cost $392 including shipping. If I had done some additional research, I would have found a shop in downtown LA that rebuilds them for $200. I haven't used them yet, but if I have this problem again I intend to take it to them. This is their info, and I believe they do most A/C compressors:
Power Cylinder Exchange
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Before doing this, you should take the car to a shop and have the A/C system evacuated (remove all the R134 from the system). Keep reading for more info on why this is a bit of a problem...
The A/C compressor is located on the lower left side of the engine (right side when facing the car).
First I removed the serpentine belt - just put a 17 mm socket with a breaker bar on the tensioner and rotate it counter-clockwise to release the belt. There is also a hole in the tensioner that you can place a finishing nail in to hold it. I just hold the tensioner in place and slip the belt off one of the pulleys and let it go back into position. I also removed the cowlings on the bottom of the car.
The bolts are somewhat difficult to reach, I had to use a socket with a universal on it to get to 2 of them. The other one is blocked by the stabilizer bar. I removed the bolts attaching the stabilizer bar to the links and was able to rotate it enough to get at the bolt. The fittings that connect the hoses to the compressor and the electrical connector were much easier to get to with the compressor detached from the car. I removed the compressor by moving it forward where the belt had been.
There is a plate on top of the compressor held by two bolts. Remove that plate and turn it upside down over a container. That is the amount of A/C system oil you want to add into the system when you charge it. The 2008 E350 uses PAG-46. It should be about 120cc, + 10cc for a new compressor + 10cc for the receiver/dryer, for a total of 140cc of oil.
I also replaced the receiver-drier as part of this procedure, as that should be replaced any time the A/C system is opened up. The receiver-drier is located below the condenser in front of the radiator. The retaining bolt that holds the lines in the receiver-drier on mine was frozen so badly that it twisted the torx head bit and I had to use a vice grip to break it loose.
I replaced the compressor and attached the lines and electrical connector before re-attaching the compressor to the vehicle. I then bolted the compressor back into position and then re-attached the stabilizer bar links. Next I replaced the serpentine belt. I didn't put the lower cowlings back until I had completed everything, just in case.
For the next steps I used an A/C R134a manifold gauge set and air vacuum pump from Harbor Freight. I used the air vacuum pump that uses a compressor and venturi effect to create the vacuum and it actually worked much better than I expected. Also, it was CHEAP. I connected the vacuum to the hose on the manifold gauge set and applied vacuum for 15 minutes. I then closed the valves and let it sit for another 15 minutes to ensure that the vacuum stayed the same and there were no leaks. Next I added the oil to the hose on the manifold that attaches to the R134a can (just carefully poured it in there prior to connecting the R134a can. Note that you have to loosen the connection to the manifold gauge set to allow it to flow into the hose). Add as much refrigerant as it will take prior to turning the system on. You can add more by turning the can upside down to get the liquid into the system, but if you do that, you must let it equalize for at least 15 minutes prior to turning it on.
- Tighten the hose to the manifold set that was loosened to add the oil, then attach the refrigerant can and turn the can upside down.
- Open the valves on the manifold gauge set to add the refrigerant. After no more refrigerant will got into the system, close the valves and wait 15 minutes.
- Turn the can right side up, open the valves on the manifold gauge set, and start the car. Turn on the A/C.
- If the compressor comes on and refrigerant is flowing, keep adding until the correct amount has been added (see below).
- If the compressor does not come on, you will need to take the car to a shop and have the A/C system reset as mentioned below.
I used 2 14 ounce cans of R134a, and a partial can to fill the system. It called for 33.6 ounces of R134a, so I used 2 full 14 ounce cans and used a postal scale to measure the weight of the partial can. I put the can on the scale while it was connected to the hose and just checked the weight until it had gone down by 5.6 ounces.
The problem I encountered was that once the system detects low refrigerant level, it shuts down the compressor and will not turn back on until the computer is reset using a STAR compatible system. There is a setting that needs to be activated by the technician that activates the compressor and will leave it active until the refrigerant level is back to normal. This costs about $50 at an indie shop with that capability. I used German Auto Specialists in Santa Clarita - http://www.yelp.com/biz/german-auto-specialists-santa-clarita. I added as much refrigerant as it would take, then took it to the shop to get the computer reset, then went back and completed the fill. I think that if you leave the A/C completely off after it has been evacuated, then fill it as much as possible prior to turning the A/C on it might work without resetting it.
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