Originally Posted by Arthur Dalton

OK..

Reading your first post, I had not realised you already had been down to the blower/reg department..

..anyway, the reg needs a low voltage signal from the CCP in order to trigger the switching transistor in the regulator.. once that is done , the regulator completes the ground of the blower circuit via blu wire [ this is a switched ground circuit,.. in other words, rather than a normal switching of a Hot side .. the switching is done on the neg ground side of the circuit]
So , when you say you have power to the blower , if you just mean you have power to the red side of the blower , that is not good enough..the red side is always HOT.. you would have to have power to both sides of the blower for it to be a complete circuit.


if there is no power at the yellow and black wires , what then.?
That is where the reg comes in.

There is a couple of simpe test points to check if you have a meter or test lamp

Behind the brake booster , on the firewall, there is a 3 wire connector .[red.blk/yl] you should have 12v across red and blk, but you should also have 2-8 volts from yellow to blk [ or gnd], depending on the speed setting at the CCP.. this is the signal that goes on down to the reg and triggers it to let the blower circuit complete to ground. The reg does the heavy work, while the trigger does not have to carry that blower load. And by varying this low volts
trigger, the reg mirrors these inputs to regulate the speed of the blower.
If this test proves you have trigger V , then the reg is prob at fault, but there is one more simple test.
But ya got to get down in there for this test:
Two wires at blower , red and blu.. if you attach a jumper wire at the blu at the blower and ground it, does the blower run on high?? ...if yes , replace reg.
You can now see that grounding the blu side of the blower simply eliminates the regulator and its function , which is to ground the blu wire when the trigger sig tells it to..thus completing the blower circuit.
End of story