Hello Club Lexus.

This winter I noticed that car heater is not blowing hot air when engine is idling (it blows cold air). I'm talking about the case when temp is set to high (even all they way) and engine coolant has warmed up to normal working temp. However it happens only at idle, if I add some gas, the air changes from cold to warm. Coolant level seems normal, however I did noticed a puddle around the expansion tank cap. Also I have these codes:

B1421: Solar sensor circuit (Passanger side)
B1424: Solar sensor circuit (Driver side)
- Faulty Solar Sensor
- Solar Sensor harness is open or shorted
- Solar Sensor circuit poor electrical connection
- Faulty Air Conditioning Amplifier

Also this might be related to another issue I have, and that is hood paint fading, supposed due to access heat coming from the engine bay (coolent temp is always ok though). Any ideas at attempting to troubleshoot this? Car is IS250 MT 2007. Thanks.

 

Have you checked the coolant in the radiator? And the condition of the radiator cap? You said the coolant level seems normal, but didn't clarify whether you actually removed the radiator cap and checked that the coolant is up to the top. Checking the coolant level in the expansion tank is not the same thing, especially if the radiator cap has failed.

 

Yep make sure coolant is topped up

 

Thanks for suggestion. Checked the coolant level when engine was fully cold and it was somewhere around or just below low mark (in the expansion tank). Added about 300 dl (half to the expansion tank, and half directly to the radiator) and now it's working fine. In the meantime I did notice that the tube feeding the coolant back to the expansion tank was disconnected. Not sure was it like that the whole time, or I disconnected it by accident when I was checking the coolant level. If it was the former then that would explain what went wrong...