zexen

hey guys,
i've got a friend with a SC300.
and today, she realized her a/c wasn't blowing cold anymore. it was basically just the fan blowing air, but the temp wouldn't go down.
i'm not sure what it could be.
any help on this would be great, guys.

Keith13b

iTrader: (3)

Check to see if the compressor is kicking on- have someone watch it when the ac is turned on. If not, could just be a bad connection, or in a worst case scenereo, the compressor could be shot. But if it turns on, you could have just leaked out all the freon. In that case, bring it to an ac repair shop, and they will give free estimates for you.

philauldridge

Before doing anything else, why not take advantage of the built-in diagnostic system in the A/C ECU. Trust me, if there is ANYTHING wrong with the system, the diagnostic system will report the problem.

To check for any diagnostic code from the A/C:

Simultaneously hold down the AUTO temp button and the Recirculation switch (center button on top row) while turning on the ignition switch.

First the system will go through an indicator check (no need be concerned about that now), then it will display two-digit numeric diagnostic codes (if any) on the temperature display. It will continue to display each encountered diagnostic problem's code in sequence until you turn off the key. If you observe codes, call the Lexus dealer and ask them to interpret, or PM me and I'll look it up.

Keep in mind that, like the main engine ECU, any codes stored when malfunctions are encountered in the system remain there, and keep getting reported indefinitely until the ECU is reset (like, new battery, or etc). Therefore, it is possible that some codes reported are from long-ago errors that may no longer exist.

To reset the A/C ECU, and clear any previous DIAG codes, remove the DOME fuse in the fuse/relay block under the hood for at least 10 seconds

lexsc3

will this work with a older SC? like a 92

philauldridge

Definitely! Mine's a '92 and I've had to let the system help tell me what's wrong several times.

hwallen172

My A/C is not experiencing any problems that I know of, but I did the diagnostic procedure just for fun. It came up with a code 21. Phil, could you interpret that for me?

Thanks,
Wiley

VVT-i

Code 21 is for Solar Sensor and it is common to see this code on all car even know nothing wrong with the solar sensor. So don't worry about it.
Zeta, take it to a good shop and get proper diagnosic. Your friend may has some freon leaking out somewhere in the AC system or some electrical circuit malfunction such as relay,compressor...who knows.

hwallen172

Thanks for the information, VVT-i. I'll just rely on my own sensors to detect the sun. I agree with your advice: A/C repairs are best left to professionials.

lexsc3

i did it thing too...it came up with 21 and 23 could you tell me what 23 means?

philauldridge

Okay, as previously stated, the code 21 (solar sensor problem) seems to be a common one that doesn't necessarily prevent the system from working. I encountered the same, and reset the AC ECU (remove the DOME fuse in the main fuse box, just after of the battery under the hood, for about 30 seconds), and it went away.... keep in mind that the ECU stores codes for ANY malfunctions it encounters indefinitely until the ECU is reset (by removing battery power)

code 23 is probably the second most common code, and indicates a problem with the refrigerant pressure switch. Of course, the switch or wiring harness COULD be bad, but most often, it means you've lost refrigerant, hence low pressure.

When this occurs, you can place a band-aid on it and add more refrigerant, but this usually just delays the inevitable, and can even serve to damage other components if refrigerant level gets too low.

At this point, it is really wise to just go to a reputable A/C specialist, let them put some dye in the fluid so they can determine where the leak is, and get the problem fixed. These very high pressure hoses and fittings don't last forever, and after 10 years or so, some of them are going to need such. Just plan on $1,000 when you head down to the shop, then you won't be too disappointed!

Gekko

I bet AC Expansion Valve needs replaced.

alto832

Wow over ten years ago
I got 3 codes 42/23/12 what are they and how can I fix it?

Seppi

I ran the diagnostic it up 00 but still no air compressor clutch is not working but ac button light is not blinking any thoughts?

EthanFic09

hello there, thanks so much for the info. I installed a new ac compressor on my sc today and it’s not quite working properly. the clutch will kick on for a couple seconds and not come back on. I tried a different relay for the ac clutch (not an oem one) but that didn’t seem to solve the issue. I did the ac ecu scan procedure and came back with codes: 20,21,22,23,24,25,26,27. not quite sure why, or possibly I did the code scan incorrectly. I’d be extremely grateful if you could help me figure this out! thanks! -Ethan