A/C Help

[NPdarkside21]

My '99 XLT 3.0 V6 blew a head gasket and now I'm replacing the engine. Upon disassembling just about everything to get it out, I had to evacuate my A/C system. Once I get the new engine and everything else put back, I need to recharge it. Now I went through the Automotive Air Conditioning 101 thread pinned to the top of this section but had some questions.
1. I need to flush my evaporator, but should I flush it WITH or AGAINST the flow to get anything that might be trapped out?
2. I'm replacing just about every component and finding oil in everything. When I recharge it, do I need to account for this extra oil in the system or is it part of the charge that goes into the compressor?
3. Do the lines HAVE to be changed or can I flush those? (they are relatively new)
4. Worst case scenario, how hard is it to replace the evaporator core?

 

[franklin2]

Unless you had a failure in the compressor, or got dirt in the system, not sure why you need to flush everything. Unless it was obviously leaking, not sure why you are replacing everything. You will find new parts sometimes are not very good compared to a good old working part.

The evaporator rarely gets contaminated, since the orifice has a screen in it that traps most things before it gets inside the evap core. The best thing to do with the evap core is clean the OUTSIDE of the coil. It sweats when it is working, and road dirt over the years gets trapped on it and turns to mud, blocking the airflow for the A/C and the heater too.

If you did have a failure, the condenser coil in front of the radiator is the one to replace. The output of the compressor goes right to that coil, and the new style coils they use with r134a are pretty much impossible to flush and get clean.

Here's a fairly convoluted description out of the manual about the oil. Maybe you can figure something out from it.




CAUTION: During normal A/C operation, oil is circulated through the system with the refrigerant, and a small amount is retained in each component. If certain components of the system are removed, some of the refrigerant oil will go with the component.Tomaintain the original total oil charge, it is necessary to compensate for the oil lost by adding oil to the system with the new part.

1. NOTE
   NOTE: Service A/C compressors are shipped without compressor oil.
   Rotate the A/C compressor shaft six to eight revolutions while collecting oil in a clean measuring device.
   1. If the amount of oil drained from the old A/C compressor is between 85-142 ml (3-5 ounces), pour the same amount plus 30 ml (1 ounce) of clean PAG Compressor Oil, YN-12C (F7AZ-19589-DA) or equivalent meeting Ford specification WSH-M1C231-Binto thenew A/C compressor.
   2. If the amount of oil that was removed from the old A/C compressor is greater than 142 ml (5 ounces), pour the same amount drained of clean PAG Compressor Oil, YN-12C (F7AZ-19589-DA) or equivalent meeting Ford specification WSH-M1C231-B intothenew A/C compressor.
   3. If the amount of oil that was removed from the old A/C compressor is less than 85 ml (3 ounces), pour 85 ml (3 ounces) of clean PAG Compressor Oil, YN-12C (F7AZ-19589-DA) or equivalent meeting Ford specification WSH-M1C231-B into the new A/Ccompressor.

1. For the suction accumulator/drier, drill two 1/2 inch holes in the suction accumulator/drier cylinder and drain the oil into a calibrated container.
   1. Add a quantity of new oil to match that drained from the old suction accumulator/drier plus 60 ml (2 ounces) of clean PAG Compressor Oil, YN-12C (F7AZ-19589-DA) or equivalent meeting Ford specification WSH-M1C231-B.

1. For the A/C evaporator core, add 89 ml (3 ounces) of clean PAG Compressor Oil, YN-12C (F7AZ-19589-DA) or equivalent meeting Ford specification WSH-M1C231-B to the suction accumulator/drier inlet tube.

1. For the A/C condenser core, add 30 ml (1 ounce) of clean PAG Compressor Oil, YN-12C (F7AZ-19589-DA) or equivalent meeting Ford specification WSH-M1C231-B to the A/C condenser core or the suction accumulator/drier inlettube.

1. Add 60 ml (2 ounces) of clean PAG Compressor Oil, YN-12C (F7AZ-19589-DA) or equivalent meeting Ford specification WSH-M1C231-B to the suction accumulator/drier inlet tube when performing each of the following repairs:
   1. installation of a new A/C evaporator core orifice
   2. installation of a new A/C compressor pressure relief valve (19D644)
   3. installation of a new refrigerant line
   4. repair of an O-ring seal leak
   5. repair of a charge port leak

1. Installation of new components that do not require discharge of refrigerant and resulting oil loss, such as the A/C cycling switch and the A/C pressure transducer, do not require additional oil.