1. Receiver Drier 2. Corrosion

[Charles5654]

Could somebody answer the following (unrelated) questions on A/C systems:

On my week-end car the compressor was replaced less than 1 year ago. Now the evaporator needs to be replaced. Normally the receiver drier is replaced every time the AC system is open. But I have probably done less than 500 miles with the AC on since the receiver drier was replaced last year. Should I replace it again?

When a refrigerant leak is found in the AC system, does the leak need to be fixed immediately to prevent humidity to get into the A/C system and cause corrosion? Or, for instance, if the leak is found at the end of the summer, you can wait until the following year to get the leak fixed?

Thanks

[tbirdtbird]

But I have probably done less than 500 miles with the AC on since the receiver drier was replaced last year. Should I replace it again?
That would be best practice. They are cheap insurance. It is more related to the fact that the system was opened, rather than mileage.

Or, for instance, if the leak is found at the end of the summer, you can wait until the following year to get the leak fixed?
Not how I would do it, atmospheric air can get in there, which is not good

[JohnHere]

Or, for instance, if the leak is found at the end of the summer, you can wait until the following year to get the leak fixed?
Not how I would do it, atmospheric air can get in there, which is not good

Continuing that thought, you could take a chance that the system would maintain at least some positive pressure during the off season, preventing outside contaminants from entering. But that isn't guaranteed, of course. If it goes completely flat, air and moisture definitely could get in, as said. So I, too, would fix the leak before the layover.

[Charles5654]

Thanks to All for the advice. I asked my mechanic to order the evaporator, the receiver/drier and the o-rings.
As you recommended, we plan on doing the work as soon as the parts become available, without waiting until the next season. As far as the need for a complete AC flushing, based on what JohnHere stated, I would assume that it depends on the residual pressure in the system that could or could not have prevented contaminants from entering the system. In case we do the flushing, it will be necessary to remove/empty the compressor and put back the specified quantity of oil or it will be sufficient to disconnect the lines from the compressor for the flushing?
Thanks 

[tbirdtbird]

Hmm, is the system flat now?
If not I would NOT flush. It can be hard to get all the flush out and some flushes are crap.
If it is flat, but has not been flat for long, were it mine, I would leak fix, evacuate and charge and not flush.
Should you flush, in my opinion no need to flush the comp, I'd flush the hoses, the evap, replace the FD/accum whichever u have, and if the condenser is PF then it cannot be flushed

Did you have a compressor burnout? If so that is a whole diff story and we'll have to start fresh

[JohnHere]

If you DO decide to flush the system (excluding the new components and any lines with mufflers), ensure that you don't use any kind of solvent to clean the compressor internals. Just drain the existing oil, measure it, refill it, rotate the shaft several times, then drain it again. Repeat that a couple of times, then refill it one final time to match the amount you originally drained out. I would also add one ounce to the new evaporator and 1/2-ounce to the new R/D before installation.

What are the make, model, and year of this vehicle?

[tbirdtbird]

What is the application?
yr make model
Chances are you could have got those components from Tim at this website for a competitive price

oops John beat me to it

[Charles5654]

What is the application?
yr make model
Chances are you could have got those components from Tim at this website for a competitive price

oops John beat me to it

I checked if the evaporator was available on this website over the phone a few days ago and it was not. The car is a 2000 Porsche 911.

[Charles5654]

tbirdtbird and JohnHere, thanks for the additional information.

I understand that, if from the measured pressure in the AC system it appears that there is a chance of contamination, it is better to flush, otherwise it is better not to flush. I am not too sure about what the defining pressure is.

As far as the condensers, they were flushed last year after the compressor failed. We did not see metal debris coming out of the lines, so I assume that the compressor just stopped working without breaking down internally. So there should not be metal in the condensers. I don't know if the condensers are parallel flow or not. As far as I know, the previous owners did not change the condensers, so they are the OEM condensers that came with the car originally. When tbirdtbird says that PF condensers cannot be flushed, it is because it is not physically possible, or because flushing is just not effective?

Thanks

[DetroitAC]

Charles, if there is ANY refrigerant inside your system you are going to be OK the just replace the evaporator. I don't flush unless it's absolutely necessary. If you have only a tiny pinhole in your evaporator and you are able to change it within a month or two, no need to flush if there is still refrigerant present. If there is a significant amount of moisture that can get in (big hole), I'd replace the dessicant in the condenser. If you can get away with changing just the evaporator, see how much oil you can drain from it when you get it out, and take a guess about how much has flowed out the HVAC condensate drain, add this in as new oil before you evacuate and charge.

my 2 cents...