Intermittent A/C issues
 

I've been experiencing some intermittent A/C issues on my 2005 UL. Start the car and there is no A/C, just warm air even after driving. Last year and once this year, the right hand side of car was warm. Sometimes turning on the rear A/C seems to help, (maybe) and in most recent case of no air at all, a restart of car fixed it immediately: ice cold on both sides and back. Turning S/V nutton off and on in the controls before that did nothing.

Last year someone suggested low a/c refrigerant, but I'm wondering if it could be a failing switch, or early stages of compressor going? I hate to go to a mechanic if they will jut tell me it is fine or not tell me truth. I'm at stage of wait to see if it happens more in next few hot months, but wondering if I should actually be proactive. This could be nothing but not sure.

Well it sounds like you absolutely have a problem, it is pretty hard to give an accurate diagnosis for your symptoms without having access to the car to do some testing and narrow down the possibilities until a culprit can be identified. If it just needs to have some refrigerant added then any competent technician would be able to take care of it for you. However if it’s lost any refrigerant then it is still losing it and the leak will need to be fixed. You really need to find someone who knows the systems in your vehicle will because the problem could be a sensor or a servo, or something that is unique to the LS430. You certainly don’t want a technician who is just going to start throwing parts at it and hoping to get lucky.
So the time you spend searching for the right shop is going to be well invested, you might have to take it to a dealership, even though they never seem to be interested in working on anything not covered under factory warranty and they charge top dollar for their trouble.
It’s best to get it repaired right away so you can enjoy it functioning properly, and the money spent will be returned if you ever sell it.

does not sound like refrigerant issue, sounds like an electrical issue. wish i could be of more help.

Thanks for replies. I'm going to wait and see. I've had rare oddball glitches with radio (no sound until car restarted) an even trans one (stuck in low gear until I restarted car, just happened once) over 15 year of ownership. Could be this is very rare or non-recurrent. a/c has been ice cold both on driver and passenger side since I posted this...

All I will say is, don't let anyone tell you it's 'the relay', because here, the A/C clutch is fed direct from the relevant ECU.
On my car, the clutch wouldn't engage because the compressor had at some point siezed, the shaft sheared and therefore not outputting a tacho signal as a 'check' for the ECU. (It was like this when I got the car; I should have realized that if it had just needed a re-gas, as the dealer claimed, then he'd have done it!) The compressor was replaced under warranty, but what wasn't covered was (1) the initial re-gas, (2) the re-gas after the new compressor was fitted, (3) the condensor that I had to have replaced because it was holed and lost all the gas immediately, and (3) the third re-gas after the new condensor was fitted. (So ££££ in total, plus aggravation.)
And then... it turned out that my rear A/C doesn't work and has been capped off! (So I have a bunch of redundant machinery taking up valuable trunk-space, that only ever fed two vents above the rear windows anyway!)
(Now you might be getting an idea why I am much less enamoured with the 430 than the 400.)