I replaced my compressor, evaporator, condenser, expansion valve, and O-rings in 2008. I don't drive the car very much and don't use the A/C much when I do drive, but it was working last summer. This year the AC is not blowing cold at all. In fact, it seems the compressor isn't even turning on judging by the idle speed (seems around 900, when it should be 600ish with compressor off, and 1000ish with compressor on IIRC).

It seems like after 6 years maybe I've lost enough refrigerant to prevent the air conditioner from working at all, which is maybe reasonable, so I'm thinking I don't need to pay to get a leak test done by a shop.

What do folks recommend for DIY AC recharge kits? Autozone has a bunch, including several over $50. What is the best deal for the money? (And any tips for the high idle are appreciated too).

 

I think that you should check if you have freon in the system first. Open the low pressure cap and push the valve. If freon comes out you are good. If it does not, you have found your problem. Next step is to turn on the A/C and check out whether the compressor clutch engages or not. If it does not, you need a new one. If the freon is gone, you might have a leak. In this case find the leak, repair it, and then recharge the system.
About a recharge kit, you could get one from Walmart. Probably the cheapest option.

 

Try to find if you have a leak. Autozone actually has a refrigerant with dye in it, to test to see if you have a leak. It's about 20 bucks. As far as the freon recharge, you can never beat a full evac of the system and recharge. If yo udo it yourself I always suggest AC Pro.

 

Yep, no pressure at all at the low pressure valve. The dilemma is, should I possibly waste $20-50 on a recharge kit, only to have it all leak out (since there is no pressure it seems like a big leak, although as I said the AC worked for 4-5 years after the last job), or should I take it to a shop for full leak test and recharge? Last time the leak was at the compressor, but since I haven't used the AC much over the years, I would really hope the new compressor is not leaking now.

I don't have a UV light to do the dye check, though I'm sure I could buy one. Is that all there is too it? I thought the shops used a pretty sophisticated leak detector device.

 

I would take it to a shop. The tools needs to diagnose the leak and repair will probably never be used again.

 

The leak can be very small and the A/C could work for few hours before it goes out. I had 03 Sentra with tiny leak and the A/C worked for a while after the system was charged.