Hello,

Please check your orifice tube first. If its full of black oil and crud then you have to flush the entire system before installing new components.

When an ac compressor fails it blew pieces of metal particles into the system. These particles go through the condenser before they got stuck to the orifice tube. Compressor fails due to lack of oil. The refrigerant oil is lost (along with R134a) through leaking old O rings, hole in condenser or evaporator.

If your condenser is the tube-fin type then flushing can be done to remove bits and pieces of metal. If its the serpentine type then its better to replace with new. Flushing serpentine condenser is not effective to completely remove these particles.

You may have to replace the accumulator too if it has not been replaced. Accumulator contains drying material to absorb remaining moisture from the system. Much of initial moisture was already removed during vacuum pumping when the system first installed. Un-removed moisture can later be absorbed by refrigerant oil (PAG) converting it into a weak acid eating away the insides of condenser and evaporator.

By opening any part of the system you're letting outside air with moisture in (even for checking orifice tube as above). Have a vacuum pump ready beside you. Plug all opened pipe or hose while you're working. The refrigerant oil (PAG) is known to absorb moisture slowly on its own. Keep the accumulator's own fitting plugged until you're ready to install it. Install it last (after filling it with refrigerant oil). Vacuum down the system for 1hr. Then you can bring the car to ac shop to charge in the refrigerant.

To answer your questions:

1. The Omega compressor should be similar in size, appearance and its fittings to your old one. Different compressor have different pumping capacity. Your cooling performance could be affected if the new compressor have lower pumping capacity than the old one. FCP parts are ok.

Your compressor may be shipped filled with refrigerant oil. In this case you can install it straight away. If your new compressor comes without oil then you have to add it prior to installation. Please refer to its manual. On some compressor oil is added thru the suction port. On some others it is added thru a fill plug. Refrigerant oil comes with three different viscosities - PAG45, PAG100 and PAG150. Please refer the compressor manual for correct oil viscosity.

Refrigerant oil balancing (i.e how much total oil in the system) is another wide topic which depends much on compressor model and car manufacturer. Please check total oil amount specified for your Volvo model. Generally speaking put half of it into the compressor and another half into accumulator. The oil will redistribute itself when the system is running.

2. Tightening should be more than snug but not over tighten. After adding refrigerant you could test leaks at the fittings by using soapy water. Tighten a bit more if it leaks.

3. Its better to replace it also. Its no fun dismantling the compressor again just to change the bushing in the future. The bushing is crucial for proper belt alignment. Improper alignment could lead to premature belt wear or noise.

4.Yes, clean all fittings at hoses and pipes when dismantling them. Its to ensure proper seating and sealing of the O rings. O ring lubrication best done using Nylog. Mineral oil is also acceptable. No need to use Teflon tapes to seal the fittings. By design the O rings are good enough for the purpose.

Hope this helps.

Amarin.