Xmon

check to see if your cabin temp sensor is connected. Mine was disconnected and I had a similar problem. Full cold or heat.

First let me say this site has been a wealth of info. Since I bought my 95 SC300 (2 months ago) I've been able to fix/replace a lot of stuff just through searching these forums!

But I have an interesting question: my overdrive switch was broken, one of the leads was actually broken off the connector. I used a copper wire and made a semi-permanent connection to turn OD off. Do any of you think this could freak out the computer, or in general, not be good. I don't plan on playing OD on/off but wanted to see what it felt like to drive only using 3 gears. -and not buy a new switch (next item on the list is a factory spoiler).

Cheers!