Hello folks,
I need some advice on my A/C problem.
I got 2008 RX350 2 months ago. Milage was a little less than 130k.
From the very beginning, I hear some rattling-like noise under the hood. Later on, I found that it becomes evident when A/C is on.

About 10 days ago, the noise suddenly becomes louder, and it became crazy noise when my wife was driving and the panel showed 'check A/C'. Yeah, it sounds like A/C compressor, and when I brought it to my mechanic, he replaced the compressor for less than $600. So I was pretty happy with the cost because I thought it could be close to a thousand.

However, on my way to home, the temperature didn't really go down though I set it to less than 70 degrees. It was a pretty hot day, but hey the loaner old Camry was good enough to blow ice cold air even after leaving the car under the sun for >6 hours.

Of course, I brought my RX to the mechanic. Unfortunately, he couldn't find any clue why it can't cool enough. Not sure what he checked, but he told me to use it for a couple of more days to see if it starts working fine. I got a thermometer and tried by myself. So far, it cools enough if the surrounding is not that hot (I can get less than 68 degrees or lower at the outlet). However, it can't blow ice cold air when it's pretty hot like 95 degrees or more. It tries to cool down (around 72 degrees when I set to 70 or lower), but it won't go further, so you feel it just blows an air without cooling.

Does anyone of you run into a similar situation? If did, what was the cause and/or solution for that? I'm planning to bring my RX back to the mechanic anyway, but I really want to know what could be wrong. I tried to look at some related sites and videos on YouTube but it seems to be really complicated so I'm just puzzled now. Any help would be appreciated.

 

Lots of reasons why AC could not be cooling. It wont cool if it is under charged, and wont cool if its over charged. Mine in my Accord was overcharged recently and would stop working on hot days. My mechanic evacuated the system and put back in the exact correct amount. It blows ice cold, but then my evaporator core was freezing when it was on LOW for more than 20 mins. I changed my cabin air filter. There are so many things that could cause it to not blow cold though.
If you do not trust that guy, you might need to find a second opinion Indy who can give you a honest diagnosis.

 

Standard for AC is to cool to 40 degrees below ambient.
Do this. Run AC and go check AC lines under the hood. By hand. If one is freezing to touch or even covered with frost, then AC works fine. Then, you either have clogged AC exchange radiator ot blender doors not operate properly, letting too much hot air into the mix. Or, your Desno climate control unit does not operate right.
If it does not - then trip to a pro AC shop it is. Blockage somewhere, poor charge, etc.

 

Thank you so much for your comments, professorm and ukrkoz!
I really appreciate this community. I used to drive 2000 RX300, and I was so happy to be able to upgrade to a newer one!
It is really disappointing that the AC's not working properly in this season. So far, I haven't returned to the mechanic yet, or haven't seen any other.
It works fine when the ambient is relatively cool (of course ), but if the car was parked under the sun for a couple of hours in the early afternoon (when hottest), AC doesn't seem to work very well at all (only slightly cold air or air not cold at all blows out). I tried to look at under the engine room, but it was just too hot and I wasn't brave enough to put my arm in there to touch any!
I wonder if there's any way to reset the AC system. As you may know, the power window switches need to be reset when the battery was replaced (or when terminals are detached). I think it is unlikely that something wrong with the AC system itself since it was working just fine before the compressor broke down.

 

For my GS300 and IS250, low refrigerant was the cause of mediocre cooling.