100 series heater only works on 80+degrees setting (1 Viewer)

[ATronic]

My heater (in the front) is working intermittently. Sometimes it just blows cold and then it will randomly start blowing hot and when it does it is nice and hot. I noticed once it is going, it heats great but I have to leave it at the 80+ degree setting. If I drop it down below that, it goes back to blowing cold, not luke warm but cold so it's all or nothing when it does work. It seems promising that when it is working there is very hot air coming out but I am wondering if I have a bad control.

Has anyone else had this problem or have any ideas? The rear works great but not enough to heat it up or defrost. As winter is headed this way I would love to get this fixed.

Thanks!

 

[Julian Stead]

What year are you driving, any difference with manual and auto settings.

 

[ATronic]

What year are you driving, any difference with manual and auto settings.

The auto mode is off when I am experiencing it. I could try and run auto and see if I get this same result. I am driving a 98.

 

[OregonLC]

Try cleaning out the cabin air sensor by your right knee; it gets a bunch of lint on it over time and stops sensing cabin temp. Max hot setting overrides the sensor. Also make sure the hose is securely attached to it, it requires negative pressure to draw air across the sensor.

 

[Ayune]

Check you coolant level too. Don't know if it applies to the LC but in my 1999 BMW (with a coolant leak) the first sign of low coolant was intermittant heat. The coolant level wasn't high enough to circulate through the heater core all the time.

 

[Spike555]

A bad thermostat can cause this too, the computer sacrifices cabin heat until the engine is hot, put the heater to full hot and it will sacrifice engine warmth for cabin warmth.

Your temp gauge can read normal and the engine is not fully warmed so you cannot use that as a actual indicator of engine temp.

 

[Julian Stead]

The heater always gets hot water unless there is a air lock so just make sure it is burped properly. Can you hear the servo move when you turn the temp up, also the cabin temp sensor mentioned needs to be checked, not sure if it matters though in manual.

 

[OutoftheMud]

Replace the control knobs. The computer that the knobs attach to god bad. Should be able to find one in a scrap yard for cheap. Try car-part.com

 

[ATronic]

Try cleaning out the cabin air sensor by your right knee; it gets a bunch of lint on it over time and stops sensing cabin temp. Max hot setting overrides the sensor. Also make sure the hose is securely attached to it, it requires negative pressure to draw air across the sensor.

Thanks! I am sure that the cabin filter hasn't been changed for a long time considering the condition that the ride was in when I got it!

 

[ATronic]

The heater always gets hot water unless there is a air lock so just make sure it is burped properly. Can you hear the servo move when you turn the temp up, also the cabin temp sensor mentioned needs to be checked, not sure if it matters though in manual.

Looks like it is burped properly. I can't hear anything when turning the temp up or down. I made sure that the hose was connected to the cabin sensor and also cleaned it. Still nothing.

 

[ATronic]

Thanks! I am sure that the cabin filter hasn't been changed for a long time considering the condition that the ride was in when I got it!

I misread originally what you wrote, I made sure that the hose is attached and I cleaned the sensor (super dirty) still no hot air.