Ranger Posted December 15, 2004 Report Share Posted December 15, 2004 My HVAC blower is not working. My first thought was the blower motor went out. I unplugged the connector and put a 12V test light on each of the 3 pins and get no light, which would indicate to me that there is no power to the motor. The "chase around chart" in the manual seems to indicate that the ACM (programmer) is at fault since it will not operate at any override settings ie: HI or LO fan speed as well as AUTO at any temp settings. As a last test to be sure it was the progammer, with my limited electrical knowledge, I assumed that if I jumped 12v to the blower motor it should operate, correct? I put a jumper wire from the ground pin to a ground and a jumper wire to each of the other 2 pin seperately and could not get the blower to run. Now I am not sure if it is the blower or the programmer, though I am leaning towards the programmer since I could not light the 12v test light at the plug. I am sure the programmer is not cheap and I would hate to replace it needlessly. Is my logic correct? Any other ideas? It's getting cold! Link to comment Share on other sites More sharing options...
gc_caddy Posted December 15, 2004 Report Share Posted December 15, 2004 When I replaced my blower motor, I also checked the current at the connector - also suspecting the ACM. It took a while to get current readings. Make sure that you run the car for a few minutes, because you don't get the blower action when the engine is cold. Eventually, current did show up at the connector. I used a digital voltmeter. I think the current is also a special "ground pulsed" circuit (or something like that) and you may need a digital meter to accurately measure it. I bought my replacement blower motor off ebay for about $200 delivered. There are a couple of genuine dealers that sell them on ebay, complete with 1 year warranty. I bought from "factoryautoparts" Link to comment Share on other sites More sharing options...
gc_caddy Posted December 15, 2004 Report Share Posted December 15, 2004 Also remember to check the fuses for the blower motor. They may have blown, if the motor got fried. There is a large MAXI fuse, under the hood beneath the plastic cover, in addition the the trunk located fuses. Link to comment Share on other sites More sharing options...
Ranger Posted December 15, 2004 Author Report Share Posted December 15, 2004 Yeah, I thought about the delay so I took a ride and filled the tank this morning before I did any checking to be sure it was up to operating temp. I thought about the fuse also but after checking the circuit in the FSM I saw that it included several other things such as the CCP (climate control panel), all of which are working fine. Link to comment Share on other sites More sharing options...
Ranger Posted December 16, 2004 Author Report Share Posted December 16, 2004 YIKES! I just checked Rockauto. $500+ for a programmer, $200+ for a blower motor. OUCH! Link to comment Share on other sites More sharing options...
Ranger Posted December 16, 2004 Author Report Share Posted December 16, 2004 I checked the fusses today and all were good. I also noticed that when I put it in auto with outside temp about 39 the A/C compressor does not turn on as it should. When I turn on defrost I hear a click from behind the glove box (programmer area), but still no A/C compressor or fan. Does this give anyone any clues to pin point the problem? Where are all the electronics experts? HELP! Link to comment Share on other sites More sharing options...
Ranger Posted December 18, 2004 Author Report Share Posted December 18, 2004 OK, apparently the 12v test light is bad. I used a DVM and with the ground probe on the ground (black) wire and the other probe on the red wire I get 14.5 - 14.7 volts. However, when I move the red probe to the grey wire I get 0.0 volts. I then turned the fan on HI and put a jumper wire from the ground spade on the motor to a ground and then a jumper wire from the + battery terminal to the red wire spade on the motor.... nothing. Moved that + jumper to the grey wire..... nothing. Then tried the + jumper to both grey and red spades.... still nothing. Shouldn't this have run the blower motor? Motor and programmer bad? How could that happen? I have heard that plug wires too close to the motor can burn it out. I just replaced them and routed them exactly as they were for the last 93K. Kept them as far as possible from the motor 1 1/2" - 2", can't get any farther. Could that have fried the blower and the programmer, and why now after 93K? Lots of questions, no answers. Link to comment Share on other sites More sharing options...
franey Posted December 18, 2004 Report Share Posted December 18, 2004 YOU NEED A NEW BLOWER . OF THE TWO THAT IS THE MOST COMMON TO GO OUT. MINE WENT AT 69 K Link to comment Share on other sites More sharing options...
Ranger Posted December 19, 2004 Author Report Share Posted December 19, 2004 YOU NEED A NEW BLOWER . OF THE TWO THAT IS THE MOST COMMON TO GO OUT. MINE WENT AT 69 K Franey, I realize that the blower is the most likely and that was my first thought but what bothers me is that I do not seem to be getting any voltage from the grey speed control wire. At the cost of these parts I'd really like to be sure before I start replacing them. I hope you are correct as the programmer is more than twice the price of the blower. Link to comment Share on other sites More sharing options...
KHE Posted December 19, 2004 Report Share Posted December 19, 2004 The speed control is a pulse width modulated signal. You really need an oscilloscope to view the signal. If you have a digital multimeter, set it to AC-RMS and you should be able to read the signal on the programming wire but an oscilloscope is still the sure bet to properly view the signal. Did you notice any "burning electrical" smell prior to the blower failing to operate? That would be a dead giveaway that the blower motor is shot. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Ranger Posted December 19, 2004 Author Report Share Posted December 19, 2004 The speed control is a pulse width modulated signal. You really need an oscilloscope to view the signal. If you have a digital multimeter, set it to AC-RMS and you should be able to read the signal on the programming wire but an oscilloscope is still the sure bet to properly view the signal. Did you notice any "burning electrical" smell prior to the blower failing to operate? That would be a dead giveaway that the blower motor is shot. Kevin, My DVM doesn't have an AC-RMS setting. No burning smells. Are you saying that I would not get a voltage reading from the grey speed wire with my DVM? You are giving me hope that it is just the blower motor. If I was sure I'd order one tomorrow. What about hot wiring it like I did? Should that have made it run if it was good? I am looking for some way to verify for sure that it is dead. Link to comment Share on other sites More sharing options...
gc_caddy Posted December 19, 2004 Report Share Posted December 19, 2004 I copied this from another site, for the board's info: Cadillac Blower Motor In 1994, Cadillac started using a brushless blower motor. It is easily recognizable by the low profile motor design and three-wire plug connector. The motor has an electronic control module built inside. The control module regulates blower speeds by pulsing the ground circuit. Pulsing of the ground circuit will show on a scanner as a 'duty cycle'. With a duty cycle of 100%, the blower will be at high speed. A duty cycle of about 40% will run the blower at low speed. The A/C programmer supplies the signal to the controller for correct blower speed. The signal is based on the A/C control panel settings and various sensor inputs. To test, take voltage readings, with a digital volt/ohm meter (DVOM), on the three wires at the blower motor. Terminal C: power supply; should measure battery voltage from fuse. Terminal A: ground; should measure 0 volt. Terminal B: signal; varying voltage: less than 4 volts - high speed between 4 and 9 volts - intermediate speeds 9-10 volts - low speed 11-12 volts - off. Diagnosis: Low or no voltage at terminal C - replace fuse and/or repair wiring. Greater than .2v on terminal A - repair ground connections and/or wiring. No voltage on terminal B - replace blower motor Varying voltage signal on terminal B - with no blower operation or blower speed will not change as signal changes - replace blower motor. No change in voltage on terminal B - blower motor is okay - testing of A/C programmer and A/C control panel is required. Link to comment Share on other sites More sharing options...
gc_caddy Posted December 19, 2004 Report Share Posted December 19, 2004 Larry, Reminder, if and when you replace the blower motor, ensure that your spark plug wires are at least 1" away from the motor's housing. I used plastic cable ties to tie up and secure the plug wires away from the housing. Link to comment Share on other sites More sharing options...
Ranger Posted December 19, 2004 Author Report Share Posted December 19, 2004 Thanks gc caddy. I did intentionally keep the plug wires as far from the blower motor as possible when I replaced them. I even wire tied them. The thing that confuses me about the above test is that I have no voltage at terminal "B" which would indicate the motor is bad, BUT that is at the connector when unpluged from the motor. So that would be the signal coming FROM the programmer. Testing the terminals at the motor seems useless because there is no power to it. Am I supposed to leave the connector plugged in to the blower motor and try to back probe the connector? It is a weather pack connector so it is hard to get a probe in there but I think it can be done if that it the proper method. As I have said, electronics is not my strong point so I need all the help I can get. Link to comment Share on other sites More sharing options...
Oldgamer Posted December 19, 2004 Report Share Posted December 19, 2004 Hey, Ranger: You may be are not an "electrician-programmer" expert, but you have very good point. The voltage on the terminal B wich provide ground to the motor should be checked when its connected to motor. Otherwize, you can't say either internal motor circut is open or circuit B from the module. Try this: connect 12V bulb between connector C and B and warm up engine enough. If module is fine light should be on. If light is off, check the voltage on terminals. C should have + (12-14V) and B should have something close to 0-4V (it can depend of bulb power). If B has the same voltage as C it means open in circuit B. If everything looks Ok, then connect that bulb to terminals C and A. It should light on all the time I guess. Try to use lamp powerfull enough, otherwize test rezult can be wrong. I'm not sure how powerfull blow motor. I think the "turn" lamp should be fine. If lamp goes on fine, measure the motor circuit resistance between terminals C and B. It should not be too high, I think below 50 ohm. Dont rush to buy motor, I hope something wrong with a wiring. The module checks air temperature, so may be something wrong with wiring to temperature sensor. If circuit is open, then it thinks sensor resistance is very high and temperature is too low. If air temperature is too low, motor should not blow cold air. I hope you'll find what's going on. Link to comment Share on other sites More sharing options...
KHE Posted December 19, 2004 Report Share Posted December 19, 2004 The speed control is a pulse width modulated signal. You really need an oscilloscope to view the signal. If you have a digital multimeter, set it to AC-RMS and you should be able to read the signal on the programming wire but an oscilloscope is still the sure bet to properly view the signal. Did you notice any "burning electrical" smell prior to the blower failing to operate? That would be a dead giveaway that the blower motor is shot. Kevin, My DVM doesn't have an AC-RMS setting. No burning smells. Are you saying that I would not get a voltage reading from the grey speed wire with my DVM? You are giving me hope that it is just the blower motor. If I was sure I'd order one tomorrow. What about hot wiring it like I did? Should that have made it run if it was good? I am looking for some way to verify for sure that it is dead. Check the voltage on terminal B with your DVM with the motor connected. I would use the DC setting. I was incorrect when I said to use an AC setting as the signal should have a DC bias to it. I would not start jumpering/hotwiring things....that can damage a lot of electronic equipment in a short time. With the motor unplugged, apply battery voltage to terminal C, ground terminal A, and ground terminal B of the motor. It should run on high. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Ranger Posted December 19, 2004 Author Report Share Posted December 19, 2004 Oldgamer, I doubt it's the wiring as nothing has been touched and I can't see wiring going bad jus like that. I really suspect the motor but need to be sure. Thanks for the reply. Kevin, I'll run some voltage tests again tomorrow morning (I'm at work right now) with the motor plugged in. I'll also try to hot wire it per your directions to see if the motor runs. I was doing it wrong. I ran battery voltage to "C", "B" and "C" & "B" with "A" grounded. If your method ground "A" & "B" with battery power to "C" does not run the motor then I know for sure that it is D.O.A. Thanks for the response guys, that is what I needed. Will post my results tomorrow. Link to comment Share on other sites More sharing options...
Ranger Posted December 20, 2004 Author Report Share Posted December 20, 2004 I ran the test as Kevin and oldgamer suggested and got ziltch. I called the local Caddy dealer and the service rep was kind enough to let me talk to the forman. He pretty much confirmed from my findings that the blower motor is definately D.O.A. I still have some indications that lead me to believe that the ACM could possibly be bad as well (god, I hope not) but the blower is a definate so I ordered one from gmpartsdirect for $212. With a little luck I'll have heat in a few days. Will post results. Link to comment Share on other sites More sharing options...
Ranger Posted December 31, 2004 Author Report Share Posted December 31, 2004 As you may know from a more recent post I finally did receive the blower motor from GMPD and did manage to get it installed today (no easy job). All is well and I now have heat again. The strange part is most indications from the chase around chart in the service manual led me to the programmer. Sure am glad I went with my insticts. BTW, I talked to a mechanic at the dealer today and he led me to believe that my recent misfire adventure probably took out the blower motor, that is, moving the wires to replace the fuel rail caused a wire to go bad and the leaking wire caused the emi to take out the blower motor shortly thereafter as the original blower motors were very suseptable to emi. He said that with the new design and the shield that comes with the motor you can have a plug wire right up against the motor and it will not affect it. Link to comment Share on other sites More sharing options...
adallak Posted December 31, 2004 Report Share Posted December 31, 2004 BTW, I talked to a mechanic at the dealer today and he led me to believe that my recent misfire adventure probably took out the blower motor, that is, moving the wires to replace the fuel rail caused a wire to go bad and the leaking wire caused the emi to take out the blower motor shortly thereafter as the original blower motors were very suseptable to emi. He said that with the new design and the shield that comes with the motor you can have a plug wire right up against the motor and it will not affect it. sounds reasonable The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
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