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2002 Rx300 Heater Problem


Kipp Noble

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My heater will only blow hot air from my defrost vents. My Auto setting turns off if I try and use any other mode than the standard feet only, which only blows cold. All screen functions light up but are not acting as normal. Radio is working fine. Any ideas would be appreciated! Thanks Kipp

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My heater will only blow hot air from my defrost vents. My Auto setting turns off if I try and use any other mode than the standard feet only, which only blows cold. All screen functions light up but are not acting as normal. Radio is working fine. Any ideas would be appreciated! Thanks Kipp

The attached Self Diagnostic routine for the A/C fan/vent system may help isolate your issue. Good luck!

A_C_Self_Diagnostic.rtf

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My heater will only blow hot air from my defrost vents. My Auto setting turns off if I try and use any other mode than the standard feet only, which only blows cold. All screen functions light up but are not acting as normal. Radio is working fine. Any ideas would be appreciated! Thanks Kipp

The attached Self Diagnostic routine for the A/C fan/vent system may help isolate your issue. Good luck!

Here is the file in PDF format just in case you are unable to open RTF files. Good luck!

A_C_System.pdf

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My heater will only blow hot air from my defrost vents. My Auto setting turns off if I try and use any other mode than the standard feet only, which only blows cold. All screen functions light up but are not acting as normal. Radio is working fine. Any ideas would be appreciated! Thanks Kipp

Once you have tracked the issue, the attached file may help test the individual components. Good luck!

A_C_System.pdf

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A few months back, my system only blew cool air only while in the heat position. The self diagnostic indicated everything was functioning properly. Ended up being the air mix servo. Do you hear a clicking noise from behind the dash on the passenger side? Kinda sounds like the CD changer cycling between CDs. Right next to the air mix servo (above and to the left of the glove box), there is the mode servo. They are about $125+ each plus labor and if you change one you might as well plan on changing the other. Some people disassemble them and clean the contacts but it is a lot of work--may as well do it right in the first place. Good luck!

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A few months back, my system only blew cool air only while in the heat position. The self diagnostic indicated everything was functioning properly. Ended up being the air mix servo. Do you hear a clicking noise from behind the dash on the passenger side? Kinda sounds like the CD changer cycling between CDs. Right next to the air mix servo (above and to the left of the glove box), there is the mode servo. They are about $125+ each plus labor and if you change one you might as well plan on changing the other. Some people disassemble them and clean the contacts but it is a lot of work--may as well do it right in the first place. Good luck!

My air mix servomotor plastic axle to arm extension was broken. I glued it back with a custom made

wood stick in the middle to re-enforce it. On the test try after I mount it, it stopped at high temperature

setting by sense the resistance and stopped. At the low temperature setting, it kept twisting the arm

and broke the axle and the piece of wood I added again.

Does any know why it won't stop? Is there a stop sensor some where to stop it from keep turning?

It seems that I need to buy a new servomotor, but I want to make sure it is not something else caused this.

thank you,

JP

99 RS300 137K miles

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