JBuckley Posted July 21, 2005 Report Share Posted July 21, 2005 Ok, guys I need a little input on this, my blower stopped working about a month ago, and When I pulled the blower motor connector on the blower motor I saw a little corrosion, I cleaned it and lot and behold it started working again. It did great for about 3 weeks then it quit again this past weekend. No codes, past or present, I pulled the connector again and not luck this time, I checked the manual and it shows that on thais year model the blower is controlled through the UART data line. It is a 3 plug connector going into the blower, Positive continous battery voltage on the red wire one end of the connector, negative on the black opposite end of connector, and less than 1/2 volt on the middle, no matter what speed I place the fan speed on. My question is does the middle control the fan speed, since I have battery voltage to the motor, something has to regulate the motor speed. And since there is no voltage that would lead me to believe that the motor is still good, and I have a ground or UART line or possible connector problem. All my functions work when you change modes, I can hear the air mix doors changing positons John Link to comment Share on other sites More sharing options...
KHE Posted July 21, 2005 Report Share Posted July 21, 2005 Ok, guys I need a little input on this, my blower stopped working about a month ago, and When I pulled the blower motor connector on the blower motor I saw a little corrosion, I cleaned it and lot and behold it started working again. It did great for about 3 weeks then it quit again this past weekend.No codes, past or present, I pulled the connector again and not luck this time, I checked the manual and it shows that on thais year model the blower is controlled through the UART data line. It is a 3 plug connector going into the blower, Positive continous battery voltage on the red wire one end of the connector, negative on the black opposite end of connector, and less than 1/2 volt on the middle, no matter what speed I place the fan speed on. My question is does the middle control the fan speed, since I have battery voltage to the motor, something has to regulate the motor speed. And since there is no voltage that would lead me to believe that the motor is still good, and I have a ground or UART line or possible connector problem. All my functions work when you change modes, I can hear the air mix doors changing positons The blower motor speed is controlled via a pulse width modulated signal. You need an oscilloscope to view the signal. I would bet that the blower motor has died. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
WarrenJ Posted July 21, 2005 Report Share Posted July 21, 2005 Actually, you can read the speed control signal with an ordinary voltmeter. As the PWM control signal has its duty cycle increased you will read a larger and larger voltage on the meter. Higher voltage ---> higher motor RPM. At only 0.5 volts, I don't *think* you're getting enough voltage to ignite the motor. Also, check the wires inside the connector housing; they're known to corrode. Regards, Warren There is no means of avoiding the final collapse of a boom brought about by credit expansion. The alternative is only whether the crisis should come sooner as the result of a voluntary abandonment of further credit expansion, or later as a final and total catastrophe of the currency system involved. - Ludwig von Mises Link to comment Share on other sites More sharing options...
KHE Posted July 21, 2005 Report Share Posted July 21, 2005 If the meter will display RMS voltages, you can read the PWM signal. I believe that a lower duty cycle (lower RMS voltage) = higher blower speed. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
KevinW Posted July 21, 2005 Report Share Posted July 21, 2005 Higher voltage ---> higher motor RPM. At only 0.5 volts, I don't *think* you're getting enough voltage to ignite the motor. Also, check the wires inside the connector housing; they're known to corrode. This type of blower is electronically commutated. The centre control lead does not supply the power to run the motor. First, make sure you're using a high impedance, digital voltmeter. Second, reading the voltage at the centre terminal of the connector is not helpful, since it is the ACP that pulls this circuit down (in a PWM fashion). If you do not wish to puncture the insulation, it is necessary to use a thin strand of copper (to make it past the connector's weatherseal while it is inserted) to obtain a correct reading. The voltage on this circuit is inversely proportional to the motor RPM; when it is high (B+), the motor will not operate. If you wish to test the blower, hook up power and ground, then connect the centre terminal to one leg of a resistor (say 2000 ohms), and ground the other leg. The higher the resistance, the slower the speed. Be sure to place the blower in a vise, since a sudden burst to full RPM may surprise you! ___________________________________________________ Link to comment Share on other sites More sharing options...
JBuckley Posted July 22, 2005 Author Report Share Posted July 22, 2005 Thanks guys for the replys, I just could not decide what method they used on the center terminal to control the motor, the manual was now real clear on that since it had constant power applied to it. The manual was not real clear on that or either I missed something, which has been known to happen, espically if you ask my wife...I am going to test it by using the center terminal grounded through a resister and double check the motor itself. Let you know the results. John John Link to comment Share on other sites More sharing options...
navion Posted July 22, 2005 Report Share Posted July 22, 2005 <!--QuoteBegin-JBuckley+ When I pulled the blower motor connector on the blower motor I saw a little corrosion, I cleaned it and lot and behold it started working again. It did great for about 3 weeks then it quit again this past weekend. And since there is no voltage that would lead me to believe that the motor is still good, and I have a ground or UART line or possible connector problem. JBuckley, You may just need to replace the connector to the blower motor. I had the exact same failure on my 94 SLS. One of the terminals in the connector had overheated and lost it's ability to grip the corresponding tab on the blower motor. If you look closely, you will notice that there is heat damage to one of the terminals. I went to a junk yard and got a good one, cut the damaged connector off & spliced the new one in. It has worked great since. I hope that is all that you need. I almost ordered a new motor, but I thought that I would try this first. (It was cheap and easy. Best of all, it worked! ) Good Luck, Britt Britt Link to comment Share on other sites More sharing options...
bigjayzway Posted July 23, 2005 Report Share Posted July 23, 2005 I just went through this on my 94 Deville.... Replace the wires, you can get them at the dealer for $39,99 Canadian! I replaced my blower, and it was ok for a couple of weeks, and did it again. I went to the dealer, and I baught the wires, they come complete(splice&play). I was so mad at myself, cause all it was, was the wires....the clips become loose, and don't create a good enough contact. I just sold my old blower to canadian95sts, cause he needed on too, but we checked the wires first! Big Jay Life is too short to grow up! Link to comment Share on other sites More sharing options...
JBuckley Posted July 26, 2005 Author Report Share Posted July 26, 2005 Ok I picked up a new blower motor connector this afternoon and I am going to replace it tomorrow morning. For any who are interested for my 94 STS the 3 wire connetor parts numbers are AC/Delco PT779 GM # 12167113, I am not sure how many other year models this connector fits. The cost was 25.00 plus tax. I figure I have a 50/50 chance of fixing my problem, I did notice the isulation on the postive wire was worn down to the bare wires, so even if I end up replacing the blower motor assembly I will still new a wiring connector, and if this does not work I will fight the blower motor R&R. John John Link to comment Share on other sites More sharing options...
JBuckley Posted July 26, 2005 Author Report Share Posted July 26, 2005 Ok blower problem fixed, new connector took care of the problem... Yeah now I can handle the 100 deg temps and 110 feel like temps in the midlads of SC. John John Link to comment Share on other sites More sharing options...
JBuckley Posted August 3, 2005 Author Report Share Posted August 3, 2005 I found the connector at the local ac/delco parts warehouse, it is ac/delco part number PT 779, cost 25.00, very easy fix comes with the butt connectors in the kit. John John Link to comment Share on other sites More sharing options...
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