This problem all stemmed back last summer when I noticed the A/C light blinking on the dash and only hot air blowing out of the vents. It was the end of the summer, so I ignored the problem until this Spring. Upon initial investigation, I realized the compressor clutch was not engaging. I then checked the A/C fuse inside the car, which was good.

The next steps was to determine if it was a mechanical or electrical problem, so I directly wired from the battery to the magnetic clutch. Fortunately, the compressor clutch engaged and was spinning, which allowed me to cross out mechanical issue or that the compressor was bad. I then used a multimeter to check for resistance on the relay as well as directly wired from the battery to the relay to check for continuity, which did click. My next assumption is that the problem could be somewhere in the A/C button switch on the dash and a part there needs to be replaced. From the information above, does anyone have any suggestions on what I should check next, what the issue might be, or any clear fixes?

Thanks for the time, appreciate it!

 

I am not 100% positive, but I think the compressor won't engage if Freon levels are low? May want to check on that.

 

how did you directly jump the battery to magnetic clutch ??
do you mean you directly jumped the battery to the ac relay ??
i am stuck on that part trying to ge tthe clutch to run manually ..

my ac clutch is not engaging all my fuses are working even the relay
i tested them also i drive a 1995 sc400 lexus

 

did you found the problem I think Iam having the same issue thanks

 

It is usually due to a low freon issue due to a leak or a blocked thermal expansion valve keeping one side too high in pressure, or in rare cases due to a very old and worn out compressor the “lock sensor” (aka “revolution sensor”) built into the A/C compressor has failed and thus the HVAC controller shuts off the compressor to protect the system from damage if the compressor were to seize.

The first thing to do is to hold down the Recirculate and Push-Auto buttons and then turn the ignition key to the ON position... but do not start the car.

The HVAC screen (assuming it is working and is visible and not needing replacement) will run a diagnostic check and begin to flash any current error codes.

Code 21 is the solar sensor and should be of no concern since it always registers an error unless it is in direct sunlight or has a flashlight pointed directly on it. That’s normal function for that.

All other A/C codes should be looked into.

However the flashing A/C light accompanied by a non-engaging compressor usually has to do with a freon leak, bad thermal expansion valve or failing compressor. The diagnostic check just helps narrow things down.

Check this thread for the list of SC A/C codes:

https://www.clublexus.com/forums/per...eed-codes.html