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Rx 400H Air Conditioning Problem


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I am having a problem with the air conditioning....The vehicle went to Lexus and they could not find a problem it.

While driving the vehicle the air conditioning works fine...When my wife left her mother in the car to go to the store the other day, she returned and the air was hot and humid. If you shut the car off and restart it, everything would be fine. It has done this quite a few times even in traffic. I did noticed when it does this the condenser was real hot but both fans where working. This is a problem when the temp out side is hot only.. Summer is coming and would like to solve the problem.

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Not sure what your specific problem is but a few things might help:

-- Use the outside (fresh) air mode instead of recirculate.

-- Make sure the A/C evaporator drain tube under the car is not clogged. You should see a small puddle of water when parking after using the A/C. If not, it could be clogged.

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Thanks for replying. I do see the small puddle like you said. What is weird the AC works fine while driving. If I stop for a few minutes with the engine running, the inside gets hot (Only on hot days). If I drive off without stopping and restarting the motor the AC will not cool. I would have to pull over shut the engine off and restart it than everything will be fine (unless stopped for a long period of time again). I feel something is getting real hot when it is not moving and shuts off for safety. Whats weird both fans are working but the condenser is real hot.

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The A/C on the hybrid 400h works whether the gas engine is running or not, since it's fully electric. There is no belt-driven AC compressor like on a non-hybrid. Normally when you stop in traffic, the engine will shut off on its own. When you say you're restarting the "engine" do you mean you're just turning the ignition off and back into "ready" mode? The engine shouldn't necessarily come back on. Also make sure you don't have dual climate control on with one side on heat so that both sides of the car are competing for their temperatures.

Are you getting any check engine light codes? Here is what the service manual shows for codes related to A/C problems:

DTC No. Detection Item

B1411/11*1 Room Temperature Sensor Circuit

B1412/12*2 Ambient Temperature Sensor Circuit

B1413/13 Evaporator Temperature Sensor Circuit

B1421/21*3 Solar Sensor Circuit (Passenger Side)

B1423/23 Pressure Switch Circuit

B1424/24*3 Solar Sensor Circuit (Driver Side)

B1431/31 Air Mix Damper Position Sensor Circuit (Passenger Side)

B1432/32 Air Inlet Damper Position Sensor Circuit

B1433/33 Air Outlet Damper Position Sensor Circuit

B1436/36 Air Mix Damper Position Sensor Circuit (Driver Side)

B1441/41 Air Mix Damper Control Servomotor Circuit (Passenger Side)

B1442/42 Air Inlet Damper Control Servomotor Circuit

B1443/43 Air Outlet Damper Control Servomotor Circuit

B1446/46 Air Mix Damper Control Servomotor Circuit (Driver Side)

B1462/62 Room Humidity Sensor Circuit

B1471/71 A/C Inverter High Voltage Power Resource System Malfunction

B1472/72 A/C Inverter High Voltage Output System Malfunction

B1473/73 A/C Inverter Start-up Signal System Malfunction

B1475/75 A/C Inverter Cooling / Heating System Malfunction

B1476/76 A/C Inverter Load System Malfunction

B1477/77 A/C Inverter Low Voltage Power Resource System Malfunction

B1498/98 Communication Malfunction (A/C Inverter Local)

B1474/74 A/C Inverter Malfunction

P0AA6-611 Hybrid Battery Voltage System Isolation Fault

B1499/99 Multiplex Communication Circuit

RX400h AC system.pdf

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  • 5 months later...

I just had to take my car to the dealership for this exact problem. Except after a day of diagnosis, they determined the compressor was gone! Not sure how that could happen on a relatively newer model (2006). I rarely had used the A/C but didn't think that would be a reason for a compressor to go. On top of that my water pump failed as well. Not a happy camper.

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  • 7 years later...

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