Cadillac Repair: 1997 A/C Blower, manual states, plug wires

Question
Bill,

Your previous help has been great. Thank you. This is a question that has me bafffled beyond my understanding. The blower went out after many years of service. I replaced it and the new one worked great... for about 4 weeks. I replaced it again and this one lasted about 3 days. Before replacing it this time, I pulled the manual and did some research on the web. The service manual states that the voltage to the motor should be 12v on one wire, ground on the other and variable on the wire coming from the programmer. Battery voltage was fine. The speed setting should read less than 4 for high and 9-10 for low. The readings I get are 3.8 for high and 1.4 for low. Although theses don't match the book, the fan works perfectly through the speed settings.

I read on a couple of sites that if the plug wires come in contact with the blower moter housing, the EMF will destroy the motor circuit. This sort of makes sense considering the design of the motor. The plug wires were all over the back of the blower.

I have installed another new motor and the readings I get still don't match the service manual, however, I have rerouted the plug wires away from the blower and I have added an additional ground wire from the heat shield to the frame.

Although my readings don't match the service manual, I don't see the odd voltage settings as causing a problem for the motor. According to the manual, the motor should be running full speed all the time, but it's running perfectly. My question is, am I ok to go ahead with this thing the way it is or am I gonna be replacing this motor again. Any help is appreciated. Thanks.

Answer
Hi Ray, Its always nice to know that advice I gave helped you out...thanks. Here's the deal with the blower motor. Inside the motor housing is a circuit board and it isn't the EMI that damages the board but the spark itself that jumps from the wire to the board. That is why there was a bulletin published that wants the wires at least 2" away from the motor and preferably inside the wire holder attached near the rear of the valve cover. I think Caddy missed something with the voltage readings but so long as the fan works and the wires are at least 2" away you should be in good shape. Bill