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Heater/ventilation Motor


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I have 96 LS on which no matter what the setting in Auto or manual the heater/ventilatin fan motor would not go beyond low setting - it will not go to higher mode to blow more air, any ideas what could be the reason?


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I've seen maybe five threads over the years from people who reported a similar problem. From what I remember, most of the cars had a non-working dealer installed Lexus phone. One of the features of the Lexus phone system was to trigger the lowering of the HVAC fan to low speed when a phone call was in progress. When one of the phone system components shorts out - sometimes due to water/corrosion - odd things happen including your problem and sending the audio system into permanent mute mode.

If your car has an old Lexus phone system, unplug all its components. Do not cut any of the phone system cables and wires! It may be enough to unplug the phone ECU in the trunk. On a 98-00 LS400 phone system, after unplugging the connectors from the ECU in the trunk, it is necessary to plug the two largest ones together to complete a circuit. I don't know/remember if the 96 phone system had similar connectors. If there is or was a handset in the center console, do some minor console disassembly and unplug the handset cradle connectors - they plug into connectors under the vent you see when the armrest is raised.

If your car has never had a Lexus phone, it could still be a problem with the phone system wiring -- all LS400's were prewired at the factory for dealer installed phones. I think I remember one case where a different issue causee the problem you are experiencing but I don't remember what it was. The problem has usually been caused by a phone system component going bad.

Let us know if your car doesn't have/never had a phone system and I'll look into it further.

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