LX450 Automatic HVAC Issue

[smoltz]

Recently purchased an LX450. It has the automatic climate control. All of the fan control options and air location seems to work, but no matter where I set the slider it's blowing max hot air, unless I set it to the lowest setting, in which case it blows max cold air.

I downloaded FSM and started poking around. Any suggestions as to most likely cause?

I see there is a reference to an ambient air temperature sensor, is that interior ambient air? If so, where is the sensor, it's not clear to me from the diagram in the FSM.

 

[inkpot]

Check to make sure the cable is connected to the coolant flow valve on the top of the firewall

 

[Pin_Head]

I have a similar problem with mine except with the slider set at 75 it is blowing max cool and when I bump it up to 80 it is blowing max hot. In between it seems to work OK for a while and then it will flip to either max cool or max hot. I tried to figure it out, but I threw in the towel and just switch it to manual when it is acting up. I don't drive it that much.

 

[smoltz]

Just to close the loop, problem was unplugged connector on HVAC unit. I found a few old threads on here that indicated that was a common problem so while I was installing my center lock diff switch, I checked and sure enough, it was unplugged. Plugged it back in, working flawlessly now.

 

[LINUS]

If you're handy, pull the climate unit (comes out as a box) - on the back is a switch (1 of mine had tape over it) - flip the dip switch position.

Auto will be disabled, but you'll have the same control like a standard issue LC.

It fix an issue I had with my old LX450.