Automotive Air Conditioning Information Forum

So here is my story, I'm working on a friends 2001 Saab 9-5. I was reading 30psi on my low side and 200 on the high, I added some refrigerant and dye and the low got up to 40psi. The high would build up to 250 and than drop back to 200 once the fan kicked on and the low slowly dropped back down 35. So I found no leaks with a uv light and slowly added more refrigerant and eventually the high stayed at 250 and the low once again lowered back down.

My best guess is the expansion valve is not working properly and bottle necking the high side refrigerant causing the low side to get lower once again. Any thoughts anyone or advice on how to troubleshoot this?

Any help would be appreciated, also the high pressure reading is after the condenser so I'm assuming its somewhat safe to say that the condenser isn't clogged but I'm gonna take some temp readings on all the lines to see if drops are occurring where they're suppose to.

What you have sounds pretty good to me. Pressures always drop when fan(s) kick on. You did not mention ambient temp- 250 psi is NOT high- it is near normal when at 80+ degrees ambient.

Of course to do it right- have refrigerant recovered and weighed- and recharged to factory (under hood labeled) spec (by weight), then lets talk pressures.....

My friend didn't want to pay to have it emptied and I felt it was overkill to empty the system, I've done this on a couple dozen of cars and it seems sufficient enough to get a reading for the high side in a general ball park (relative to ambient temp). I've only had a handful of systems emptied when replacing components or fixing leaks (which I than flushed components, replaced dryer/receiver or accumulator, replaced oil, ran vacuum, etc) Than I would weigh out refrigerant, recharge and would give very similar high side readings as if I didn't empty the system (with the compressor engaging of course)

It was 70 degrees out which general info suggests that I should get about 35-40 on the low side and I didn't mention this before but the center vent blew out at 55 degrees even after charging the system. My concern here isn't the numeric value at the high side, its that its NOT lowering ANYMORE when the fan kicks on and the low side doesn't stay at 40 when charging. Also it still isn't blowing any colder.

Mabye the fan clutch, going to put a fan on the condenser and see if that made a difference. I've also been told the evaporator can clog up easier with an expansion valve instead of a orifice tube. Thought maybe the expansion valve isn't opening up properly causing refrigerant not to recirculate but I would think the high side would continue to rise if so. I plan on taking a reading before starting the car next time (static pressure), told the low and high should be the same on both sides. I also plan on taking temp readings on the lines and seeing if components are functioning properly (ex: colder after the condenser)

Any info would be appreciated, wont get to work on this for a couple of days so trying to get more prepared. Sorry for the long posts, figured more info was better.

Also there was no humidity, we're known for our snow here in WI.