I don't know what it IS, but I know what it ISN'T. It ISN'T your cabin temperature sensor. If you are still getting cold air out of the center vents despite the temp. wheel being set to the hottest setting, there's something else wrong other than the temperature sensor.

Seems to me it would either have to be the pushbutton control panel or a defective air door, but I am NOT a climate control expert.

If you don't get more specific help, consider reposting with a more descriptive subject line.

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Steve
'93 400E