Climate Control = Full Hot or Full Cold & No Inbetween!

[md1twal3]

Here's another issue my LS has been experiencing for a while. At 60 degree setting on the dual climate control, AC is full cold. At 65 degrees or anything above, temperature inside the car goes full hot...90 degrees (even if it's set on 66, 68, 70, etc.).

From my research, it sounds like I have an interior heat control sensor in the dash that could be the cause. (part number XW4Z-19C734-BA)

I have no problem tearing into it and testing it but am confused about whether my system has the 3 sensor or 1 sensor system. I am guessing 3 because of the dual capability but then don't know which of the three I need to test.

Anyone able to help out with this?

 

[joegr]

Your DCCV has failed in the classic way, fully open all the time.
Since you have a gen I, you have a cold air bypass door. That allows you to get full cooling at 65, because it switches to bypass the heater cores. At 66 and above it is in the normal position.

Replace the DCCV and you will be okay. It's not a temperature sensor.

 

[md1twal3]

I replaced that with a new Motorcraft one when I replaced the engine a year or so ago. Had the problem before I replaced it and after (still). I thought that was the cause but apparently wasn't.

What's next?

 

[joegr]

I replaced that with a new Motorcraft one when I replaced the engine a year or so ago. Had the problem before I replaced it and after (still). I thought that was the cause but apparently wasn't.

What's next?

Run the DATC self diagnostics.
Check the DCCV/AC Compressor fuse. Check the wiring between the DCCV and the DATC. Also make sure the connector is fully mated to the DCCV.
Measure the resistance of each of the two DCCV coils.