Waleedjatt

hey all.

I recently read a post on this forum regarding AC issues with LS, I saw many people suggesting to change the pressure switch. I did change the pressure switch and went to a garage to refill the freon.

It started working perfectly, blowing cold air, however it was short lived, it stopped working again, and now it works once in a blue moon by luck, if i keep turning the AC on and off it starts working at some point and then goes off again.

My question is how come it only worked while refilling the freon?

When the AC stops working, there is a bad odor.

Just want some insight from you guys, maybe it is an electrical issue? A clogged pipe?

Because when it turns on the cooling is awesome, so i dont really feel anything is wrong with the compressor.

Hope you guys can help..

Waleedjatt

Hey brother,

Thanks for the quick response.

I will definately check that, but just to add, previously when my AC stopped working just few weeks ago before i changed my pressure switch, it was showing that the freon is completely filled and there were no leaks. Even now when it turns on sometimes it blows cold air, would that be possible even after freon leaking?

However, most of the people aren't able to fillup the freon without putting some pressure in the compressor first, for example they completely evacuated the freon and when they were refilling it wasnt going in, later they filled some air inside first and then started refilling after which it went in smoothly.

Is there a specific way to fill up the freon in lexus? Or is it just like any other car?

Waleedjatt

I was able to check the glass and the rotation, both seem fine, rotation is normal, when I turned on the car now at max AC it started cooling very little, like you would have at 75C. When i rev up the rpm cooling increases slightly.

Im not able to check the resistance because I believe it wont be possible without opening all the covers and removing the condenser.

However, would it be possible for you to send me the workshop manual for ls430? As I'm unable to find it online, it would be really helpful.

Waleedjatt

Waleedjatt

I will explain you the complete procedure how they fill the freon.

First they completely evacuate the freon and connect it to a big compressor like this (picture attached ) they start it up and let the air out from the second nozle until its completely clear. Then they close the second nozle up, and start pressurising the compressor, after a while they get some kind of clear cooling system lubricant in which they insert a nozzle, so the pressure built up sucks the lubricant after which they start filling up the freon the normal way.

Waleedjatt

I guess thats exactly the way they do it, create negative pressure and refill the freon.

Is there any possibility that it is some kind of an electrical issue? A relay? A damaged cable?

Or maybe something to do with a serpentine belt?

Sorry to bother you with all the questions.

And yeah, is it possible to get the workshop manual as pdf?

BradTank

They could have also overfilled it with refrigerant.

The pressure is too great after it cools for a short time period, it cuts the compressor off. That's what what the cutoff switch is supposed to do.

If you don't have the tools to properly charge it up yourself, I would go to a reputable shop (a different one) and let them troubleshoot it and then you can figure out what is going on rather than say throwing a guess at it like you did with the pressure switch. It should be way cheaper.


If an auto shop doesn't know what to do in this situation, find a different shop. This is very basic for auto shops that work on AC systems.

Waleedjatt

Even if the pressure is too great, it would be back to normal after a few hours, when i turn the car on after like say 7 or 8 hours, the A/C doesnt respond, I would agree if AC would only kick in on starting the car, my AC just kicks in randomly at any point

Waleedjatt

Lets say this is the pressure gauge, the blue one was between 35 nd 30 when ever the compressor would kick in it would go to 35 when stops goes to 30, at what level should the high side be?

BradTank

This is a generic chart to give a ballpark range

Waleedjatt

Is there anything else, except the freon or pressure switch that can cause the same problem?

Anything electrical?

BradTank

Clogged expansion valve
Bad serpentine belt that needs to be replaced as its slipping
Blend door
Evaporator temperature sensor not giving correct reading
condenser fan motor
Evaporator fan
Bad compressor
Clogged evaporator drain

There's lots more
And anything electrical in the system like a short wiring or a bad ground could do it also.

You would just have to troubleshoot it one by one. I personally think its worth paying a shop that has the right tools and experience and knows what to look for as it doesn't follow the usual pattern.

Waleedjatt

Update guys,

Yesterday night and today morning, AC worked great for like 10 15 minutes and then got shutdown as usual, still cant pinpoint what it could be.

However last time when AC guys evacuated freon, it looked black and oily (picture attached) also ive noticed the compressor turns on everytime but freom doesnt come through, only occasionally, any input from you guys about this?

rkw77080

You may have excessive moisture in the system. This will cause moisture to freeze at the expansion valve and stop the flow of refrigerant, which coincides with your observation. You will need to evacuate the system and maintain a vacuum on it for a long time (45 minutes to an hour) to get rid of any residual moisture. Then fill the system with the right amount of HFC−134a (R134a) refrigerant. For single A/C: 650 +/- 50 g (22.93 +/- 1.76 oz.); for dual A/C: 900 +/- 50 g (31.74 +/- 1.76 oz.)

Here is a Youtube video that demonstrates how to properly replace refrigerant for a Toyota/Lexus AC

rkw77080

Here is a test to confirm if you have too much moisture in the system.