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A/C system diagnostics- Need codes.

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Old 06-28-14, 07:35 PM   #46
t2d2
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I've had a minor issue where my cold air (without A/C running) is a fair bit warmer than outside air temperature. I was starting to look into heater control valve stuff and the possibility that it's remaining open and allowing coolant to circulate, making the cooling fight the heating. While researching that, I ran across the diagnostic tests for the HVAC system ... didn't realize that process existed.

I've got one current (beeping) code: #21 - Solar Sensor Circuit

I haven't been able to find much about it, other than it often is triggered by testing in the dark. However, I tested while it was fairly bright outside, although at 6pm and not in direct sunlight. I did re-run the test with a flashlight pointed at the sensor, and that didn't change anything. (It is the clear plastic, flat sensor on the left side of the dash, right? Not the reddish dome sensor on the right side?)

Anyone know what the next step(s) would be in diagnosing the Solar Sensor Circuit? I didn't get any Code 22 with the engine running, as suggested earlier in the thread.

Edit: Just remembered one of the things I did find; a faulty coolant temp sensor could create the problem. I have faulty plugs/wires on both of my sensors waiting to be replaced, so there could be a easy explanation there.
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Old 06-29-14, 02:04 PM   #47
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False alarm. I re-checked today in semi-direct sunlight (overcast, but a bit brighter than yesterday's testing conditions) and there are no codes. The Solar Sensor must be quite finicky as far as what it considers sufficient sunlight. So, back to the original thinking of it being heater control valve related...
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Old 09-21-14, 08:35 PM   #48
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bumping this thread guys....
95 sc400 pulling a code 42... servo inlet door. the air blows nothing but hot and all controls work just fine. ive cleaned up the ground on the ac comp to make sure it wasnt that. the ac comp does not engage ever. anyboy have exp with this code?
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Old 09-23-14, 09:06 PM   #49
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bumpin for a any info......
i dunno if its been said or not but once you get your codes pulled up, you can push the "fresh" air button and the system will began a check. it'll run through different settings and test different aspects of the ac components. you can pause it on any phase of the test by pushing the "recirculation" button and resume the tests by pushing the "fresh" air button. i found it helpful to pull the glove box out so i could watch the difference in the system as it tested the stuff.
on another note: i think i have discovered my ac comp to be inop. im going to replace it and hope that it fixes my problem since nobody wants to chime in.
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Old 10-03-14, 08:51 AM   #50
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bump for those guys that were concerned and those having similar problems.
code 41,42,43 FIX
basic problems: a/c light flashing with the ac never actually cutting on. the blower would work and all functions of the ac worked very well with the exception of the compressor never cutting on. system was charged and all wires were chased and proven to have good connections. the compressor wheel would spin only if provoked but would not maintain a constant spin. i bought a used compressor from a friend and swapped it out. i pulled the vacuum and charge the system up.
no codes. no problems. everything works great.
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ac, button, circuit, codes, control, ecu, heater, invehicle, jump, lexus, pressure, problems, recirculate, recirculation, sc300, sensor, switch, temperature

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