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Hi all,
1992 968:
I have a slow AC leak I have not been able to locate so I thought I'd replace the O rings for the expansion valve and evaporator. I got to the expansion valve easily enough by pulling the blower assembly (6x 8mm screws around the base) and
removed the insulation around the lines in this area. I can at this point R&R the expansion valve however I do not see the other connections. How are they accessed? Do you go in from inside the firewall somehow through that piece of insulated cardboard?
I have the glovebox out but could only touch the expansion valve from the footwell, not really do anything with it unless I try to remove ducting.
Also if someone has a suggestion for products to replace the pipe insulation here as well as the crumbling foam tape around the blower outlet area that'd be helpful.
Here is a pic. I wonder if I should be trimming this flap so I can get to the connections or going in from the engine-side. View forward from behind the expansion valve towards the firewall.
Before you go to the trouble of replacing the O rings, I would suggest that you locate the source of the leak, using fluorescent dye and uv light source. Most AC shops will be able to do so at a minimal cost. More likely to fix the problem than easter egging it.
I've got dye in the system now but still have not found where it's leaking from. Next step is to look for dye at the connections I have not seen yet. I hoped to see UV dye at the expansion valve fittings but did not. I think the only connections I have not been able to inspect are the ones buried in the firewall there.
Most common location for refrigerant leaks is the compressor clutch shaft seal.
It's located right behind the compressor clutch but you have to remove the clutch and bearing to get to it.
If you are using UV dye, look in that area.
Thanks, I'll check it again. When I have had leaks from the compressor I also had an oil drip though and I have not noticed one. I've also replaced the compressor with one from a car with working AC and that did not sort out the slow leak.
Most common location for refrigerant leaks is the compressor clutch shaft seal.
It's located right behind the compressor clutch but you have to remove the clutch and bearing to get to it.
If you are using UV dye, look in that area.
+1. This has been my experience in years of Porsche AC setups on 924/944s. Leak in compressor every time. Most likely the clutch or even on those little valves in the fittings on low side connector. Have an AC specific shop do vacuum and dye test for a few hours. They will find it. Otherwise you may be chasing an expensive green ghost for a long while.
I think the dye is not working well because the system leaks down while not running. That said, I may have found a leak in the condenser under the airbox. The condenser is pretty beat up and grungy so I think I will replace it. I've had this slow leak since I bought the car, maybe the PO's shop that replaced the head damaged the condenser in the process. I think I see a faint glowing trace of oil coming down between the fins.
I wish I could check those evaporator connections though, it'd be good to check for leaks there and put in HNBR O-rings while I have the fan unit out.
01-13-2019, 07:10 PM
Late 944 / 968 AC evaporator O rings, foam, etc.
