JamFan

I have a 2003 SC430, and my Climate Control Cluster seems fine. I can adjust the blower up and down or change the mode. All functions seem to work. Except that if I raise temps the heater won't blow hot air, and if I lower the temps, the A/C won't blow cold air. What would cause this?

Raven01750

Does this failure apply when the controls are in "Auto", dual. Do the blowers change speed trying to meet temp request? If yes, then it is most likely a failed blower door motor. There have been quite a few threads on this subject. Try a forum search and you should find quite a bit of information. Good luck.

Paul

JamFan

Doesn't seem to matter whether or not I have it on auto or not. I can manually manipulate everything, and the problem is the same.

Raven01750

So to simplify the issue. You have no air coming from any of the vents?

Paul

JamFan

Nor do I have any heat coming from any of the vents. Raising the temps to 85 does not make the heat come on, and lowering the temps to 65 does not make the AC come on. It will blow vent air at whatever blower setting I use, low or high. Thanks for your help.

DshngDaryl

Are both passenger and Driver side giving you trouble? I think there are 4 blend doors in the SC, it seems like if both sides are giving you trouble, it wouldn't be caused by just one door.

What I would do is disconnect your battery for a few minutes. After you reconnect it, the blend doors will open and close to learn their position. That may fix your problem.

If not, you can read this post. It maybe a fuse issue
https://www.clublexus.com/forums/sc4...004-sc430.html

Have you tried pushing your recirculation button? Maybe you will get some air that way. If you do, I would say it is probably your blend doors.

As I was writing this, I recalled you can have your car do an A/C self test. Here are the directions for a LS, but they should be same for the SC
https://www.clublexus.com/forums/ls-...ditioning.html

GmanSC

There is a thermistor somewhere in the AC/Heater loop. I bet that your problem. Do you have TechStream or any kind of code reader? If you don’t, take your car to a mechanic, he should find out the problem.

Raven01750

That A/C test should be a pin. And it does work. Tested it earlier.

Paul

Bgw70

It could be the actuators as Daryl said above. I will post some threads for you.
you can change the temp and look under the dash to see it the temp actuator is moving.
there are four actuators. One on drivers side, three on passenger side.

The four actuators control,
1. drivers side heat and cold
2. passenger side heat and cold
3. fresh or recirculated air
4. air direction, floor, defrost and vent.

Actuators buzzing sound.
https://www.clublexus.com/forums/sc4...s-are-hot.html

this is all about actuators from the GS forums...the actuators operate the same.
https://www.clublexus.com/forums/gs-...ete-guide.html

the last post in this thread has files showing the actuator locations.
https://www.clublexus.com/forums/sc4...004-sc430.html