I bought my 2004 LS 430 off the showroom. Lately I have been having a problem with the air conditioning system. Sometimes the A/C system work, sometimes it does not. The dealer could not figure it out. My wife told me that I have to turn the engine off and restart the engine again in order for the system to work. Today I did just that and sure enough it worked. Who said women don't know about cars. She is better than the expensive mechanics at Lexus dealers.
Can anyone here help me figure out what is the problem? I changed the battery lately that seemed to have it started doing that. Any relation to the new battery? Thank you.

 

Check your ground wire and make sure u got it tight.

 

The compressor could be bad. When mine was bad, sometimes the AC would work and sometimes it wouldn't. When it wouldn't, it would blow hot air for about ten minutes and then start blowing cold. The compressor was locking up, but it would only do it sporadically. Took two years to properly diagnose.

 

I got a scared yesterday. The AC was on but no air blowing out, not even hot air. For some odd reason, it started working later.

 

This is no guarantee that you have the same cause, but I had - exactly - the same symptoms as you.
Here is what I would recommend:
1. Check the battery voltage with a digital multimeter. The analog ones (if you can find one :-) do not have adequate resolution. I used a very convenient (and cheap) 3 1/2 digit DMM that plugged into the cigarette lighter & I think I paid about $3 (including shipping) for it. Check e-bay.
2. See if the A/C works right after the battery has been charged (either from driving or using a charger).
I found that if the no-load voltage was low (perhaps less than 11.5 V), the A/C behaved just as you describe.
If it was higher, it worked correctly. BTW, your wife is a genius!
3. I am guessing that your new battery is not taking a full charge. THe DMM will also give you a great snapshot of your alternator functioning.

If you are reading over 12.5 V (with the ignition ON, before starting), this is not your problem.
The next steps could be:
1. Check magnetic clutch engaging.
2. Check freon (need a gauge/manifold set).
3. Check more expensive stuff (like the compressor).

Hope this helps.

 

I had a similar thing. This problem is caused by ambient sensor which reading outside temp and then will adjust your climate control. Sometimes it did take a while to start blowing the air. Replaced it and all is fine.