jasepb

I recently changed the radiator after my car overheated due to coolant loss. However, I am now getting really hot air from vents without turning on heater after about 5 minutes of driving and the engine temperature gauge is at middle/half mark. If I turn on the heater, then the temperature setting show "Hot". I've checked and coolant in radiator and overflow tank are full. Has any one encountered this issue before? Is this a thermostat issue?

Bocatrip

Changing the thermostat after radiator replacement is always a good idea. Was the car running hot before you noticed the low coolant?

jimbosr1

you may be still low on coolant.When filling you should have you car running and have the heat on max.

rkw77080

It sounds like your heater valve maybe stuck open. Please take a look at Post #3 on the link below for more details...
https://www.clublexus.com/forums/ls-...goes-cold.html

vredniykot

is your car tuned to CNN?

jasepb

Thank you so much. It was indeed the heater control valve. I think my mechanic turned on the heater to max when refilling coolant, and the heater control valve stayed at max hot when I got the car back. Is this heater control valve just stay at the last climate control setting or does it suppose to move back to some neutral position by itself?

razvy

The heater control valve suppose to open and closed when you call for heat or defrost , that lever it's control by a actuator / servo you don't suppose to move the control valve by hand only if the cable it's disconnected , if it doesn't respond to the cabin command you need to find it and see what is wrong , you can have a bad actuator or a broken arm or bad control module.

jasepb

My heater control valve is opening and closing properly if I turn on either heater or ac. I was checking if it supposed to move back to neutral/close if heater is not turned on.