Okay a while back (3 years ago), my brother and I had almost matching cars.
A Mazda 626. Only differences, mine is blue, his grey, and his is a DX
model (no big difference though). Unfortunately the car ended up in a wreck
and was declared totalled (though it wasn't that bad). It made the car
great for parts for the other one though. Recently my brother bought a new
car so I got his Mazda 626 and I've been trying to fix up some of the
problems his had.
The problem is the the heater fan switch doesn't totally work. The settings are Off up to 4. Now the switch works for Off, 1, 2, 3, yet when I switch it to 4 the fan goes off. Now I pulled the fan motor from the previous Mazda and pluged it in. It didn't work either. This leads me to believe that the actual switch is bad. Unfortunately this switch seems almost impossible to get out. It as well as the temp and heating level switch are all in a connected unit. I've pull apart the dash of the old Mazda yet I'm unable to get the switch unit out. The temp and level switch have the sort of tight wire connection, while the speed switch is just a normal switch. I'm looking for advice as to how to disconnect the unit.
I have a 89 Mazda 626 with a similar problem. The speed control swith only worked on position 3 and 4. I also thought it could be the switch. To get switch out from the control panel it was neccessary for me to first pull the panel out a little and then removed the screws holding the switch in place in the heater control unit. To find you need to look up at the bottom of the control panel when you have it pulled out a little (they were a little gold in color). Once I had removed the screws I disconnected the switch from the connector behind the heater control panel - that gave a little more room to move the switch when I had it unscrewed from the heater control panel. I was then able to wiggle it free from the panel.
However ..... when I got it out I discovered that the switch was fine.
I trace the wires to a black encasing/connector just behind the fan motor. It is here where the problem was. This housed the resistors that are switched in/out to control the speed but it seems that some water has seeped in and damaged the resistors and connectors for the 1st and 2nd position. Once I cleaned it up and replaced the resisitors the fan worked on all positions.