Help! No Heat And My Fingers Are Going Numb.

[ihateduke]

I have a 99 RX300 with no history of HVAC problems. Starting Monday morning, when I started up the car in 30 degree weather, I set the heat on high/auto. As usual, nothing happened for about 3 minutes until the car heated up. Then gradually the fan speed rose and the screen showed it as blowing on the floor. So far so good.

The problem is that the air was actually blowing at mid height and then randomly it jumps to the defrost. To make it worse, the air is totally cold. I let it run for 20 minutes and it never really changed. If I hit a pot hole while driving the air flow jumps between (Defrost, Mid-Level, Floor).

Later in that same day it started to work just fine. Since then it has been broken again in the same manner. Is this is a computer related issue, is the heater coil going bad or something else?

Please help before I get frostbite!

Thanks in advance.

[lexrx3]

I have a 99 RX300 with no history of HVAC problems. Starting Monday morning, when I started up the car in 30 degree weather, I set the heat on high/auto. As usual, nothing happened for about 3 minutes until the car heated up. Then gradually the fan speed rose and the screen showed it as blowing on the floor. So far so good.

The problem is that the air was actually blowing at mid height and then randomly it jumps to the defrost. To make it worse, the air is totally cold. I let it run for 20 minutes and it never really changed. If I hit a pot hole while driving the air flow jumps between (Defrost, Mid-Level, Floor).

Later in that same day it started to work just fine. Since then it has been broken again in the same manner. Is this is a computer related issue, is the heater coil going bad or something else?

Please help before I get frostbite!

Thanks in advance.

My 2001 RX 3000 lost floor heat and defroster. All other ventilation outlets worked. I took it to a Toyota dealer (always cheaper than Lexus) and they said the computor system was in a "fail safe" mode. They "re-initialized" the system and it works fine. This happened 11/7/06 and everything is still fine. They didn't know why it happened but its fixed. It cost me $91.00 for the diagnostic/labor. They compared what they did to re-booting your computer. Maybe your problem could be similiar. Good luck.

[gp1200x]

I wonder if simply disconnecting the battery and letting it sit for a half hour would give the same result as their "reboot".

[lexrx3]

I wonder if simply disconnecting the battery and letting it sit for a half hour would give the same result as their "reboot".

Someone in another post mentioned the same thing. Perhaps it would work and its certainly worth a try. If that worked I'd sure feel like an idiot. :chairshot:

[wwest]

I have a 99 RX300 with no history of HVAC problems. Starting Monday morning, when I started up the car in 30 degree weather, I set the heat on high/auto. As usual, nothing happened for about 3 minutes until the car heated up. Then gradually the fan speed rose and the screen showed it as blowing on the floor. So far so good.

The problem is that the air was actually blowing at mid height and then randomly it jumps to the defrost. To make it worse, the air is totally cold. I let it run for 20 minutes and it never really changed. If I hit a pot hole while driving the air flow jumps between (Defrost, Mid-Level, Floor).

Later in that same day it started to work just fine. Since then it has been broken again in the same manner. Is this is a computer related issue, is the heater coil going bad or something else?

Please help before I get frostbite!

Thanks in advance.

Sounds as if the one of the position feedback potentiameter's "wipers" (moving contact) for the airflow outlet routing servomotor might be open/failing, but my best guess would be an open or intermittent connection to the entire servomotor assembly.

There is a simple test procedure you can use that puts the climate control through a full function test sequence and that will tell you which component has failed or is intermittent.