QuestionQUESTION: Hi Ronald,
I have been waiting to ask you this question about my 96 grand voyager. My resistor block fuse and blower relay all are fine, yet my blower is not running, as a matter of fact, the whole control unit seems to be not working. I have manually turn on my blower and found that the motor is fine and blowing air. BCM may be bad. Please advice me how can I by pass the BCM and activate my heating system manually. The van is old and I don't want to spent much on it. Thanks in advance
AL-Amin
ANSWER: Hi Al-Amin,
Actually the BCM is not involved in the heater/AC unit. I would wonder if you might not have a fuse that is blown. There are three of them: fuses #6 (20A), 12 (10A), and 21 (40A). So check and make sure that those are all showing conductivity (a small crack can develop which makes the fuse "open" even though it looks good). In order to control the temperature of the air and its distribution you have to get the control unit going again. The blower alone will not be satisfactory I suspect so lets try and get the whole unit going again.
The fuse numbers are taken from the '98 manual so if these don't seem to be identified as related to the heater/AC let me know. I believe the '96 is like the '98, but I can't be certain
Roland
PS I would appreciate your rating my answer by using the "thank and rate" tab below. Thank you
---------- FOLLOW-UP ----------
QUESTION: All fuses were OK. I managed to find out the relay and turn the relay on manually and now I could operate the Fan on all speed. but since the blend door is closed I don't get any air pass beyond that. I am only able to get the blow from the glass (I remove the one of the door on the passenger side by the blower) motor and open that door and get the blow air on the winshield only. but its not cold. Heater core is hot to the touch. Please instruct me how can I open that blend door. Which wire and what voltage will make the actuator work to just open that section for now. Thanks
AnswerHi AL-Amin,
I would be cautious about trying to fake out the blend door actuator with a jumped voltage supply as it operates on 5V supply and you might do damage to the solid state circuitry that feeds back position info to the control panel etc. I would suggest instead that you remove the control and take a look at the interface between the internal pins from the blue plug's pin 10 and the circuit board because that solder joint has been found by others to be prone to cracking. If that happens then while the fuse #6 is good its current is actually not getting through to the circuit board, which render it inoperative. You could take a soldering pencil/gun and reheat that joint and solve the problem if that is why the entire unit seems to be "dead".
If that doesn't work then I would suggest instead that you remove the lower steering column cover (the part that includes the parking brake release handle, which you remove the handle mechanism and disconnect its cable) entirely so you can see the left end of the HVAC distribution housing which is the side that has the blend door actuator(s) (two if you have dual zone controls) and that you remove the acutators and move the blend door by hand to a position that does provide heat. The blend door actuator(s) have 5 wires:dark blue/red, dark blue/white, pink/dark blue, red/white, and dark blue gray. The functioning as you can see involves both the actuator and the feedback signals so that is why I would not try doing an electrical by-passing of the system for fear of doing damage. The two wires that actually move the door are the first two listed above. So you could unplug the supply plug and try jumping 5v in either polarity to move the door back and forth to the extreme positions without any interconnections to the rest of the circuit. Maybe use a 6 volt lantern battery to do this? But the proper fix is probably what I said first,above, to check the circuit board.
Roland
PS Thanks for the kind words and evaluation given previously.
