Hi. I have a 93 SDV that blows cold almost all of the time. It's been doing this all season, except for about a 1 minute spot a couple nights ago where it blew warm. Any ideas?

My first thought was that the coolant level is low. This starves the heating coil of coolant and thus no heat. You would have noticed a cooling problem by now if this was the case.

Second thought was the temperature door actuator. If memory serves, there is an actuating rod behind the glove box that has a little plastic adjustable keeper that will strip out. Sometimes the temp door is binding and you'll have to disassemble the whole thing to free it up.

Good luck!

Id say your heater core is going bad