Well, my car is back on the road with a functioning AC. I ended up replacing the compressor and wanted to follow up on this thread with some info for anyone else who may consider tackling this job.
First, I'd like to thank Mathew (Wicked1) (as well as Josh (ECS) and Eddie (Azzuro Corsa Motorsports) here in the US) for responding to my PMs regarding this job. It's great to have professional Maserati specialists who actively participate on the forums and are willing to help someone who is unlikely to ever be one of their direct customers due to distance. Thanks again!
Originally, I intended to fully document the procedure and post with pictures. However, I found this writeup (by JAGPURR, thanks!!) on removing the exhaust manifold in the Technical Fixes forum(
4200 Exhaust Manifold Removal). This is a great writeup and I couldn't see much point in trying to replicate his work. In addition, there is at least one version of the service notes available (thanks again!) which has instructions for replacing the starter which is located above the AC compressor and requires a very similar procedure to access.
Regarding my original question about removing the compressor, the recommended procedure is to raise the engine and remove the driver's side exhaust manifold in order to access the AC compressor. I suggest following this recommendation. I do believe that it may be possible to replace the compressor without lifting the engine and completely removing the manifold, but it would be very difficult. I say this because I was able to remove the compressor without lifting the engine. I unmounted the AC compressor and then removed the exhaust manifold studs and pulled it from the block but didn't remove if completely. This allowed me to remove the AC compressor. The problem came in the reassembly. It was very difficult to secure the AC lines and the compressor mount bolts. After trying, I decided to go ahead and follow the recommended procedure to make sure that the compressor was properly installed and nothing (especially the manifold) was damaged.
In order to remove the exhaust manifold the following high level steps are required (My car is LHD so adjust drivers/passenger side as necessary for RHD):
-Remove intake hose and air flow sensor
-Remove the secondary air valve (Note the two gaskets which should be replaced)
-Loosen the driver's side catalytic converter pipe and slide towards rear of the car to free up that end of the exhaust manifold
-Repeat for the passenger side. This step is probably not required since you are not pulling the passenger side manifold. However, I did as a precaution for lifting the engine.
-Remove the exhaust manifold studs and free the manifold. Some of these (especially those nearer the firewall) are more easily accessed from under the car. This required a great deal of patience as some of the studs are difficult to see and reach. I suspect this becomes easier with practice, but I hope to never reach that level of skill (read practice).
Note the four manifold gaskets which should be replaced when reinstalling the manifold.
-Free the engine mount bolts
-Lift the engine. Those three words are fairly loaded. I didn't see an easy way to lift the engine from the top. The service notes suggest jacking the engine up from the bottom and supply this picture:
I used a transmission jack and a block of wood.
-Remove the exhaust manifold. The service notes indicate that this may be a two person job with one person pushing the raised engine to the side in order for the other person to then remove the manifold. I didn't find this necessary.
At this point, the AC compressor is easy to access. Here's a picture of the compressor installed with the manifold and heat shield removed:
Installation is the reverse of above. Servicing the ac system (removing/adding freon, pulling a vacuum, ...) is very straight forward and no different from any other R134 system.
Overall, I wouldn't say that this job is particularly hard, but it requires time and patience. I was told that book time is about eight hours. It took me much longer, but I tend to really take my time and spread the work over multiple days as time permits.
