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B1423 on code check but not ac self-diagnostic

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by LEARNER, Aug 30, 2020.

  1. LEARNER

    LEARNER Junior Member

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    I had my 2004 Prius AC evac and recharged, dye check, sniffer check etc at AAA on dedicated machine

    As the AC starts out fine but upon driving in peters out and persistent B1476

    No leaks found and everything checked out, fans operating normal blowing right direction

    I drive for a couple weeks but the same problem

    I take it back there for a recheck for leaks since it was free and the tech actually did evac and recharge and everything done last time plus fault code check and reported B1423 and B1476.

    He sounded pretty believable but I was skeptical because B1423 has never come up on my AC Self-Diagnostic. Only B1476

    Is it possible B1423 to show up on shops computer code check but not on the Prius AC Self-Diagnostic?

    I was about to go ahead and have the aftermarket AC Compressor replaced since the fans are operational, no leaks found and passed all tests.

    Another thing I have to add for a complete picture is the ambient temperature on my screen starts out with the correct temp but as I drive everyday it goes up 7 degrees hotter than the actual ambient temperature.
     
  2. dolj

    dolj Senior Member

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    That would suggest that hot engine room air is leaking into in front of the condenser/radiator, the area where the temperature sensor is.

    What does the repair manual (more info) say about the B1476? Here is a sample:

    DTC No. Detection Item Trouble Area Memory
    1 B1476 A/C Inverter Load System Malfunction
    • - Volume of refrigerant - Electric inverter compressor (w/ motor compressor)
    • Cooling fan circuit
    -

    DESCRIPTION
    The A/C inverter stops compressor control and outputs the DTC if the rotation load is too great or too small while controlling motor rotation in the A/C inverter.

    HINT:
    Possible reasons could be as follows: Load is low when the refrigerant gas leaks or load is too great when refrigerant gas is excessively charged, an insufficient cooling performance due to condenser fan circuit trouble, or the compressor locked up.

    DTC No. Detection Condition Trouble Area
    1 B1476 Motor's rotation load while the compressor is operating is too great or too small.
    • Volume of refrigerant
    • Electric inverter compressor (w/ motor compressor)
    • Cooling fan circuit

    NOTICE:
    The A/C inverter is integrated with the inverter with converter. It is necessary to replace the PCU box if the A/C inverter (inverter with converter) needs to be replaced because the A/C inverter (inverter with converter) cannot be replaced alone.


    B1423:
    The pressure switch to detect the refrigerant pressure is located in the sight glass side of the pipe on the high-pressure side. This DTC is output when the refrigerant pressure is either significantly low (below 196 kPa (2.0 kgf/cm2, 28 psi) or significantly high (over 3,140 kPa (32.0 kgf/cm2, 455 psi). Then the pressure switch sends appropriate signals to the air conditioning amplifier. The pressure switch has built-in switches to detect high and low pressure and is turned off when either is determined to be defective. The air conditioning amplifier continuously monitors the pressure switch signal after the power switch is turned ON (IG). It stops compressor control and outputs the DTC when it detects the signal indicating that the switch is turned OFF.

    DTC No. Detection Condition Trouble Area
    1 B1423 When either condition below is met:
    • Open in the pressure sensor circuit.
    • Abnormal refrigerant pressure: Below 196 kPa (2.0 kgf/cm2 28 psi) Over 3140 kPa (32.0 kgf/cm2 455 psi)
    • Pressure switch
    • Wire harness between pressure switch and body ground
    • Multiplex communication circuit
    • Refrigerant pipeline
    • Air conditioning amplifier


    My first thought would be was the exact volume (by weight) of refrigerant (R134a) added when the system was recharged. If the volume was correct and is now less, then there is a leak.

    I hope there is something useful there.
     
    LEARNER and SFO like this.
  3. LEARNER

    LEARNER Junior Member

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    The last evac showed no loss, no leaks and passed all standard tests, both fans are working when ac is on blowing in the correct direction.

    Although I've read they blow at variable speeds but mine seem to blowing at high speed all the time

    I've read the diagnostics above many times and have read every post on it to gain insights.

    The shrouds in the front over the radiator and condensor and behind are missing but there is the rubber seal air dam still intact to the hood yet the ambient sensor is getting hotter than the true ambient temperature that I have measured multiple times. Rising 7 degrees above ambient after 5 miles of driving.

    This B1423 may be a red herring as it does not show up on my AC self-diagnostic but the only way to be sure I guess is have someone else competent to do a code check preferably techstream although I want to try some of those apps to check for codes and monitor engine and inverter temps while driving.

    Could the engine or inverter be over heating but not enough to cause a warning light to come on causing the thermal limiter or pressure switch to shut down the AC Compressor after I drive 5-6 miles in the heat because the load is too great?

    Over the past 2 years the AC Compressor has been replaced 3 times. The first 2 years ago then 2 a year ago although they were aftermarket but still I'm thinking some condition is causing this like maybe engine over heating particularly in the Summer.

    Looking over the history of car repairs I see my inverter pump was replaced twice and the control valve and the fluid level is correct with turbulence in the reservoir.

    The engine coolant pump has never been replaced but the coolant level is fine and it has been changed at manufacturer intervals.

    I did ask the last shop AAA to monitor the Inverter and Engine temps which they may have done if they did it only in park not having time to do that on a test drive.

    Soon as I get an Android phone long over due as I have a Windows 8.1 phone I want to get a bluetooth OBD adapter and those different apps to monitor these different temps myself. Disconnect the 12 volt battery at the quick disconnects for a 5 minutes which has cleared the codes before and see what the temps are when the code B1476 sets again like it always does.

    3 years ago the oil pressure light went off which is not good and pulled into a gas station to get oil to add right away. Like many other posts mention the oil is very low when that light goes off.

    Wondering if damage was done then despite adding oil right away
    causing engine to run hot yet my oil level is perfect

    I'm usually pretty good at checking all my fluids and my oil burning had slowed down to almost none after changing more often (Full synthetic 5W 30 Mobile One High mileage) .

    OR the engine coolant pump or system is not cooling adequately.

    Now parked in the shade the AC will cool pretty good for a long time which is great. Have to say I am a Prius Camper so many years (original owner) of thousands of idle hours using AC. I should have had the AC serviced regularly but I was ignorant then thinking that is something you do only when the AC starts blowing warmer air.

    I wanted to rule these things out before replacing with an oem compressor wasting a lot of money.

    Very frustrating dealing with this a year now being stuck here (although I had been recovering from surgery) as I travel the country working contracts on top of $1300 sunk into this problem already.
     
  4. dolj

    dolj Senior Member

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    Our resident A/C tech recommends only using quality Denso compressors. I'm not sure if that means only using OEM, but the OEM is Denso.

    Search out videos posted here by @lech auto air conditionin to see if you can find any videos where he discusses compressors.
     
  5. LEARNER

    LEARNER Junior Member

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    Yes I learned that and have watched many of his videos. Wish there was a guy like him here on the east coast.

    Still kicking myself for not going with OEM Denso with a shop not competent in hybrid AC repairs although Toyota was not much more competent in diagnostics with 4 visits with an expensive replacement of air mix servo door that helped none and giving back to me with B1476 still present telling me "Oh that will go away soon".

    I pray that not being comaptible especially under stress is the issue and that a OEM Denso will solve the main problem even if pricey still less than gambling on another used Prius after I do some more testing to get more data before I find a good AC Technician to look for anything I missed which is probably a lot