Skier76

The A/C in our 2009 IS250 is blowing somewhat cool...not cold air. I've read for other Lexus models, you can do a diagnostic check of the HVAC system. Is that possible on the 2nd generation IS?

Bichon

If I recall correctly, you can access the service menu on navigation equipped vehicles by holding the "Info" button pressed in, while quickly switching the light stalk between "off" and "parking lights" about 5 times. I don't remember whether there is an HVAC menu item on that screen. Even if there is, it's unlikely to help much.

Rather, I'd make sure that the condenser coil is clean and that the condenser fan is operational, and check then check the refrigerant charge. If you choose to do this yourself, make certain that you follow instructions carefully, purging the lines of air before connecting them to the car, lest you introduce moisture and air into the system. If the A/C was previously serviced by a DIYer, there may already be air and moisture in the system; if so, bring it to an A/C shop so that they can evacuate with a vacuum pump and recharge. If the system is low on charge, a proper repair involves finding and fixing the leak, before evacuating and recharging.

Skier76

Thanks Bichon. I'll give that a try and let you know what happens. Our car is equiped with nav, so it's worth a shot.

I checked briefly yesterday and the fan was operating as soon as the car was turned on. The compressor was spinning as well. No difference in vent temperature when stopped or moving (both in town and highway) I guess I'll take a look at the sight glass next to see how things look there. Is that near the driver's side headlight?

Gs3500

Any luck? What did u see on the NaV?

Skier76

I haven't had a chance to try this yet. My wife has the car and she's traveling right now. I should be able to try this out over the weekend. I'll be sure to provide an update.

Skier76

Well, the problem seems to have solved itself for now. The A/C is back to being cold. Granted, the temps have dropped a bit; and so has the UV index. The day it was giving us issues it was in the 90's and very sunny. Car is black with a black interior. Wondering if the A/C system was just having an issue keeping up.

strikeraj

I would just take it to a shop and make sure the correct amount of refridgerant is charged in the system. That is what I would expect to have a slightly lower a/c performance.

Skier76

We took the car on a longer road trip this weekend and I can explain things in more detail now.

When heading out, the A/C was blowing "cool", rather than very cold. It was 90+ and humid out. The car had sat outside all day. About an hour into the ride, the temps dropped due to some rain. From that point, the A/C was blowing cold. Temps were in the mid/upper 80's and the sun was setting.

So, something is up with the system. I verified the fans are working, and will kick on to high speed as needed. No bubbles in the A/C sight glass. Compressor is engaging and staying engaged.

As strikeraj said, probably time to have someone look at it.