How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Eric Your Own Question
Eric, Automotive Repair Shop Manager
Category: Lexus
Satisfied Customers: 31891
Experience:  20+ yrs. experience as repair shop manager and technician.
Type Your Lexus Question Here...
Eric is online now
A new question is answered every 9 seconds

I'm having ac problems with my 1999 RX300 Lexus. I think the

Customer Question

I'm having ac problems with my 1999 RX300 Lexus. I think the cabin temp. sensor is out and causing my AC system to not blow cold and blow hot air when the interior temp. get hot. Is that possible?
Submitted: 1 year ago.
Category: Lexus
Expert:  Eric replied 1 year ago.
I am sorry that you have not been helped yet. I just came online and saw your question
While it is possible for the cabin temp sensor on the evaporator to cause it to no blow cold, it would not cause the air to come out of the defrost vents, so unless there are multiple issues going on, this is not the problem
I need to know if yours has manual or automatic climate controls to see where the issue may lie
Please remember to rate service using the rating page so that I may receive credit. Thanks
Customer: replied 1 year ago.
Eric, I have an automatic climate control. I'm guessing that I do have multiple issues as you stated. Another issue is that the climate control does not work as it should. The air flow temp is either cold or warm, there is really no controlling it in between.
Customer: replied 1 year ago.
I guess if you can just help me with the most important issue, for me it would be to be able to have cold air flow even when the interior temp is high. Let me know if you need more info. Thanks.
Expert:  Eric replied 1 year ago.


Ok, lets check for fault codes - follow directions below(fault codes will display where the temperature normally displays). Write down the fault code numbers and post them here for me


a. Turn the ignition switch on while pressing the A/C control AUTO switch and R/F SW simultaneously.

b. Check that all the indicators light up and go off at 1 second intervals 4 times in succession.

- After the indicator check is ended, the diagnostic trouble code check begins automatically.
- Press the OFF switch when desiring to cancel the check mode.


a. After entering the sensor check mode, press the R/F switch.
b. Since each damper, motor arid relay automatically operates at 1 second intervals beginning in order from 20 in the temperature display, check the temperature and air flow visually and by hand.

If a slower display is desired, press the A/C switch and change it to step operation. Each time the A/C switch is pressed, the display changes by 1 step.

- Code are displayed in order from the smaller to the larger numbers.
- To cancel the check mode, press the Off switch.

Related Lexus Questions