A/C repair after 8 years

[ganun]

Ac just cool, after many years of trouble free cold. I thought it just needed a shot of freon but the shot did nothing. Low at 0 hi at 150.
Recovered 60 oz to my horror. Don't just add if there's a problem!.

[gasmask]

From what I remember reading. The system is designed to slowly leak over time since there is pinholes throughout the system on purpose? Someone in the midwest had created a solution that replaces the entire A/C system and is around 2k I think.

[walt]

If your low is zero, sounds like you might have an obstruction in your expansion valve.

[ganun]

Diagnosis:
Tiny mesh screen at inlet of expansion valve clogged with rust. Pulled out the screen with some tweezers and took some pictures.





Source of rust must be the drier. Curious what the inside of the drier looks like I cut it open, YIKES!
(No wonder it's to be changed every time the system is opened)
But it's been in service since 2012.
That bag is sewn midway on the delivery tube with the desicant media balls inside. Aint much of a filter as it's a loose fit in the body but if it were a filter it would only catch incoming debris, maybe. The tube that delivers to the expansion valve picks up from the bottom, where junk collects.
In hindsight two things I could have done better; verified the oil charge (drier was dry)and changed out the drier when the system was opened to install a Hi performance front condenser from Griffiths maybe 5 yrs ago. Very nice unit BTW.







So removed the comp to check its oil level and sure enough it had about 10ml of yellow oil rather than 60ml. Flushed it with some fresh oil and filled it with 60ml.

[Mike Andrew]

Damm, that is just plain nasty and scary. Looks like the R/D captured all of the junk and may have contributed it as well.

[ganun]

The rest of the story.
Here is what the new valve looks like, see the filterscreen at the inlet.


Reassembly
Both Sanden and Porsche manuals matched the oil quantities so 15ml in the drier, 30ml in the evap and 60ml in the comp. Lots of O-rings, #6, 8, 10 and maybe others.
I gave the evap a flush with freon and quickly capped it, same with the drier.
Installed everything but before connecting the inlet hose to the expansion valve a flush of the system from the compressor connection. The whole hi side got a flush. Didn't worry about the low side since the evap got a flush and the hose is a straight run to compressor fitting.





Filling the system
I used a 2 stage pump and 4 ports with valves so there would be no need to break connections to attach the freon cylinder. Sorry no pictures. Pulled to 500 microns (which pegs the gauges) and held 24 hrs to 1500, good enough IMO.
A couple of picture of equipment used.







Results
Slowly added freon to 26 oz then went up in 2 oz intervals to 30 oz when the pressures were 20/190 at idle and 17/200 at fast idle. Cold inside the car, about 40F at the outlets. At 34oz 20/200 but I noticed the body of the exp valve frosting over and evap outlet sweating profusely ( like me !), it's very humid. Took it up to 36oz 21/210 and stopped. The ir thermometer would read in the 30s but I couldn't find my Omega thermocouple.
I really wanted to measure superheat but the ir would read hi 50s at the evap outlet to get a ~33 SH. I like to see the line temp lower maybe in the hi 40s or lo 50s and the pressure higher, like 30s. But the would mean adding more than the 36oz in there already. Leave well enough alone?????
So took it out for a spin it was around 1pm sun out and hot
Result : it's COLD
(PS R-134a Label attached per Charlie)
I don't have a shop, don't do this for a living, just retired old guy having fun.