My 2013 Hyundai Tucson had been leaking refrigerant and lasted only few days. I put in the dye, UVed it to find refrigerant all over the low service valve.

After replacing valve core, the refrigerant lasts 2 weeks. And I still see a little bit of dye on 1) low port valve and 2) near one of the O ring (though it felt me like a shape of 8).

Also when I start the car for 1-2 min I could smell the refrigerant in the cabin. Not sure if refrigerant or mold. but after a few mins whatever odor is it, goes away.

Could AC Leak from O ring be so crazy as to drain all refrigerant in 2 weeks? What could I do further to fix the leaking AC low valve? Where else could leak be present (I scanned that no dye present near the compressor or on the hoses).

  • How do you know it is only leaking at the low pressure valve? Did you draw a vacuum on it to see if it would hold before you put more refrigerant into the system? Commented Aug 12, 2022 at 0:02
  • I dont believe it is the only source, i just replacing valve core helped. I am seeking assistance on how ti diagnose and fix the leak further
    – 10101010
    Commented Aug 12, 2022 at 2:15

1 Answer 1


Vehicle ac repairs are unforgiving of mistakes as there are zero short cuts. Every ac system from the factory are considered sealed with the two service ports expected to be used since glass smooth roads don't exist when every pothole rattles ac systems until damage occurs. Whether you know it or not, vehicle ac systems are under pressure when not used, mimicking outside temperatures; 70F/70 psi, 80F/80 psi, etc. When running, two operating pressures occur; low side approximately 30 psi and high side varying with outside temps and humidity - between 125 psi to 250 psi+. Guess how any leak will eventually release most of this refrigerant? It won't matter whether damage is nearly invisible or catastrophic as in front end damage to rupture condenser coil and hard tubing. A uv blacklight is very valuable to any diyer willing to spend time and effort to find the elusive leak as most vehicles should have dye installed during factory assembly. The uv light must be shined everywhere; above, below, everywhere ac plumbing and parts exist to reveal where damage occurred. We're not discussing tire leaks of 35 psi. Standby ac pressures of at least twice tire pressures will leak refrigerant easily from any corroded fitting, crack in aluminum tubing, loosened fittings, etc. Once a leak(s) is/are found, repairs require new O-rings, flat seals, refrigerant oil, electric vacuum pump and refrigerant gauges plus knowledge in repairs to restore factory ac cooling. There's more to ac repairs than cans of r134a and sealer (not advised).

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