Just picked up immaculate '13 LX570 rear A/C not cold enough...intermittent driver footwell hiss (1 Viewer)

[dcs111]

This thread was helpful. I've been dealing with the hiss for close to a year now and was under the impression the issue was the A/C bearing going out. The front A/C has always been ice cold since I started hearing the noise and the cool box also. I noticed the rear A/C not blowing as cold as it used to however that must have been a recent development. So the leak must be really slow. Anyhow I had to find out if this was the solution so I left work and hooked the gauges up at the house and sure enough the pressure was still within spec but was on the low side. knowing about the sight glass was nice, topped off the freon and all three units are blowing ice cold in silence. Glad I don't have to pull off the compressor and such...

I posted on this issue somewhere... too lazy to go search, but synopsis as follows: 7K road trip.. we hit the desert and the whole AC system timed out for about 30minutes. I am guessing it was a protection mechanism to avoid damaging system. it never happened again the rest of trip. brought to our local mechanic who does our work and asked that he check system pressures and sure enough it was low. he ran some sort of dye and found a leak at one of the lines leading to the rear part of the system. he simply cleaned up the area, replaced an o-ring within the line fitting, recharged and bam.. cool as a cucumber and at a very small price. best of luck with the slow leaks - i would recommend finding a mechanic you trust and have them do the dye check. it could be a $0.50 part that solves it!