Sorry that this posting is rather lengthy, but I can't describe it thoroughly without being a tad wordy.

Here goes: Now that the seatcover washing celebration is dying down, we're ready to put the freshly washed covers back on the seats. But before doing so....I'm puzzled by what appear to be two different configurations of seat heaters and their accompanying thermostats. From a salvage car, we have two additional front seats, purchased because they had much seatcovers in much better condition. Not sure what year car they came from, but they are probably older than my 93 240. Nevertheless, the two different sets of front seats have what appear to be two different types of seat heaters...at least that's what I'm guessing them to be.

On my 93, there is a nylon mesh panel glued to the foam seat cushion pad. Within the panel is a disk shaped sensor about an inch in diameter. On one side of the sensor (about two inches away) is a flexible "spot" also about an inch in diameter, which has a single wire going to it. From the "spot" is another wire going over to the sensor. Two inches on the other side of the donut is another "spot" with a wire coming from it. This "spot" does NOT have a wire going directly to the donut sensor. There are no apparent heating elements within the nylong mesh panel, at least not that I can detect. When checking for continuity, using the two wires coming/going from the seat (at 80F), I could not detect any continuity. FYI, the donut shaped sensor rests over a 2.5" divet in the rear topside of the seat cushion. My question about this unit......what is it anyway? Should there be a heating unit in the seat too, that is currently missing??

Okay.....now for the second set of front seats from an older car. Removing the seatcovers reveals a plastic grid with a maze of wires taped to it (no nylon mesh panel as in the other two seats described above). In line with the wires within the grid is a round sensor which is unquestionably the heated seat thermostat. There is one of these plastic grids in the seat cushion, and another identical plastic grid unit in the upright backrest cushion. Neither of these thermostats rest over a divet in the seat cushion. A continuity test of both units reveals that there is continuity. So.....I'm assuming that these units are functional. These units appear to be operating as they should...correct?

My questions: what are the donut shaped sensors in the mesh panel in the 93 seats? Are they seat heater thermostats, or possibly for some other function? If they are in fact seat heater thermostats, why is there no plastic grid system of wires connected to them...presuming that they are actually heat sensing thermostats? Or, should I simply use the plastic grid units of the older seats, rather than using the "mystery" units that came with the 93? I want to have functioning seat heaters after everthing is reassembled, but don't want to put something back in place that doesn't function or isn't as it should be. The 93 seat heaters were not tested for functionality before disassembly as I assumed they would be identical to the older style heating units......so much for taking anything for granted!

Well, that's about it....I don't really know which units to use!

Thanks in advance to the experienced on this list who can shed some light on this!

Daryl