Air Con Help

Hi all, I'm having some issues with the A/C on my 2001 996, and would appreciate some help understanding what's going on. I know there's a lot of content on this topic, but when I search nothing quite aligns for my situation into a eureka moment. Timeline: Last year: First summer since having bought car, A/C not working so I regassed it using a DIY kit. In hindsight this was dumb as the system was showing 0psi, so should have been obvious there was a leak, but I YOLO'd it anyway. Immediately after gassing: hissing sound from 'inside' dash, near expansion valve. No cold air. Day after: back to 0psi. This summer: Clean rads and inspect condensers, these were shot, so suspecting these were the source of the leak I replaced them myself along with the desiccator. Had the system vacuum tested and regassed at a local tyre shop franchise. Finally, cold air. Low speed rad fans didn't come on, but high speed fans intermittently did. Cold air continues. A week or so after: still cold air, but weird 'resonant' noise coming from front of the car, wailing as revs go up and down. A/C system reporting what seemed 'normal' pressures around 28-30psi when on. Compressor engages and sounds normal. Hissing from the expansion valve area again. High speed fan no longer comes on. A few days later/Now: No cold air, A/C pressures still look 'normal'. Loud hissing from inside dash. Tried topping up the gas, which makes little difference to the running pressure of the A/C, the hissing sound (if anything it gets louder) or temperature at the vents. The desiccator and the high pressure line into it hot to the touch, maybe 60 degrees C. Compressor still engages and sounds normal. Current suspects are: The rad fans clearly not functioning normally, but the air doesn't get colder as I run the car at higher speeds so could it be this? Blend doors - I have the dreaded black foam but the 'bleed' from the directed vent to the other vents isn't too bad and I do get hot air if I want. Something else - needs a new evap core? A very slow leak. But given system pressure has been stable, I'm not convinced by this. Unless my A/C Pro gauge just isn't accurate. Have I made any glaring mistakes here? Help or advice would be much appreciated! Thanks!

First, get your rad fans working, both on low and on high. The low speed fans turn on whenever the AC is on (manually). Could be bad relays or bad resistors. Second, take your car to an AC specialist. They will evacuate the system, fill it with nitrogen for a system check. Then have it refilled with the correct amount of freon and ac compressor oil. Have them add UV dye when refilling. That makes checking for leaks in the future super easy. The AC system is not something you can DIY in the driveway.

Thanks DBJoe996, I appreciate the reply. To clarify, I did take the car recently to a nationally franchised garage with a professional air con machine. They did a full service with vacuum check etc and regassed it. The whole process took around 45 minutes. The guy gave me a thumbs up and said everything was fine, and it did blow cold, for a period, before failing before I tried any DIY. The air con worked to begin with despite the fact the low speed fans weren�t working and nothing has changed in that respect. I believe my fans still work on high speed when triggered by the engine temp, but are no longer coming on with the A/C as they intermittently did after the service. I�ll try and do a more thorough test of the fans later, jumping relays etc. I do intend to fix them, but also wondering how likely is it that they�re the root cause in this scenario if they haven�t actually got any worse/changed in their function in the given period. Cheers!

Ok, so I took it back to the A/C shop who last re-gassed it and have confirmed a slow leak somewhere. Slow enough that it passes their machine's vacuum test, but severe enough that when they evacuated the system they only recovered ~120g of the original 900g of freon (plus my small top up). I think that my attempt at using the A/C Pro pressure gauge was unhelpful, because whilst it showed the system held some pressure, it wasn't accurate enough to show that there was a decrease in available gas over time. Time to buy a UV torch and get digging, I guess. Wish me luck!

The AC service place probably has dye they can use to find the leak. Hopefully it�s in an easy to access location.

Sadly looks like it�s in one of the worse places that it could have been! The bracket that holds the pipes towards the rear of the right hand side of the car has broken and the rubber insert has disintegrated on one side. The pipe now has a leak facing the car, kind of �inside� the bracket so it seems a repair in situ is off the cards. Annoyingly it�s the larger pipe (low pressure?), which looks like it�s a real pig to replace. At this stage the system is totally depressurised, so I may as well remove the pipe myself to get a feel for how difficult the orientation is. How do people feel about repairs of this issue? I could take it to be welded if the pipe is otherwise �clean�. I�m not averse to spending money on a new part I just hate scrapping things unnecessarily if they can be renewed.

Quotes source post: 19505203

Well, if you can actually see the crack/hole/etc, in the pipe, and can get to the leaky area,? Then sand it down completely clean and use some JB weld for a repair. It might hold for a long time or forever. And its easy to check for leaks with some soap suds. And it will only cost you a tube of epoxy and some sand paper/wire brush. They do make epoxy repair kits for many different types of refrigeration pipe repairs. Tranne use epoxy in oem connections of copper to aluminum tube. J B weld should be fine(or any quality epoxy of your choice) as long as you can clean the total area of the damage down to bare metal.... Obviously a new pipe is the best repair. That is the most work/cost. But don't discount a good epoxy job either... jmo

The difficulty is I can't exactly see the hole as it's on the bracket side. I can see the UV dye inside the bracket, and I could establish the general area by sliding some insulation tape over the pipe and listening to the hissing get muffled (while it still had gas), but I wouldn't be confident making an epoxy repair without taking the pipe off of the car. I think the thing I'm most worried about is having to put a pipe (repaired or new) back onto the car. Seems like that's going to have to happen either way and If I don't want to do it once, I surely don't want to do it twice. I may just bite the bullet on the new part. There seems to be very little in terms of online tutorial on this subject, so if I manage to not completely ***** it up, I might try and make a video to help the next person. Does seem to be a fairly common problem!

Quotes source post: 19505584

If you can disconnect/remove the bracket holding the line and maybe any other close by brackets/clips to give you room to pull the line down enough to get at the leaky area.... Them mix up few drops of dawn dish soap and warm water frothed/beat up with your finger tips to a thick suds. Put some gas in the system till you hear the hissing and then slather soap suds on the area. You will immediately see the soap suds bubble up/spit out of the leak thus exactly pinpointing the leak for repair.... jmo

If u want to charge the system for testing u should use nitrogen and u should change the dryer out as its been open to atmosphere and that ruins them. The ac hoses do have junction points and it should be posible to remove them but i have not done it with the engine in the car. They r also insanely expensive so u may want to try dc auto or la dismantler for a used line.