A/C fan going crazy
Thread Starter
Instructor
Joined: Jul 2012
Posts: 235
Likes: 9
From: Winter Garden Florida
A/C fan going crazy
on my 86 I have the A/C controller that has the hot or cold buttons and displays the inside temp setting when running the A/C in the Auto mode.
just today the fan started working intermitently. the A/C fan had been running on high speed for about the first 10 minutes after starting and driving the car. the compressor and the rest of the system seemed to be working normally.
any ideas what it could be? does the fan have the 3 electrical coils that make the different fan speeds?
where are they located and how hard are they to change? is it something else?
every day with this car seems to be a different problem to solve.
what an adventure.
all suggestions are welcome
John
just today the fan started working intermitently. the A/C fan had been running on high speed for about the first 10 minutes after starting and driving the car. the compressor and the rest of the system seemed to be working normally.
any ideas what it could be? does the fan have the 3 electrical coils that make the different fan speeds?
where are they located and how hard are they to change? is it something else?
every day with this car seems to be a different problem to solve.
what an adventure.
all suggestions are welcome
John
Racer
Joined: Mar 2007
Posts: 365
Likes: 92
From: Arkansas
I have the same issue on my '86.....I'm betting our problem is the blower control module. It's located on top of the blower housing under the hood. I took the electronic control unit out and dissassembled and cleaned it, as I had heard that suggested, but it didn't fix it.
On the bright side, I have no doubt that this is what drained two batteries for me- since I unplugged the blower control unit, the car can set for weeks and have no problem starting.
I haven't had time to worry about mine much, I've been busy changing the leaking water pump, which by the way is a royal pain..
On the bright side, I have no doubt that this is what drained two batteries for me- since I unplugged the blower control unit, the car can set for weeks and have no problem starting.
I haven't had time to worry about mine much, I've been busy changing the leaking water pump, which by the way is a royal pain..
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
for hi speed
Elec a/c has above mentioned BCM
The BCM is a direct link between the batt and blower motor. It is a solid state electronic device that acts as a switch and resistor pack to control blower speed.
( also controls the A/c compressor )
When BCM goes faulty it can ( randomly and at any time ) turn on the motor ; even with key off
Also check the blower fuse, gives the same motor run situation
http://forums.corvetteforum.com/1573982448-post12.html
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Several years ago I had a problem with my C68 system -- no blower fan. I took the motor speed control module out of the evaporator housing and thought, "Well, THAT looks expensive".
It turned out to be a corroded connector pin. I found it when I accidentally bumped the wiring harness just the right way while poking around and it suddenly started working. All good now.
Speaking of blower fuses, I just happened to take a picture for somebody who didn't know where it was located:
It turned out to be a corroded connector pin. I found it when I accidentally bumped the wiring harness just the right way while poking around and it suddenly started working. All good now.
Speaking of blower fuses, I just happened to take a picture for somebody who didn't know where it was located:
Last edited by Cliff Harris; Aug 18, 2012 at 10:16 PM.
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Rod, I'm always the nitpicker, I know, but I've had my Resistor Module out many times and there are actually three resistors. The A/C Blower Control Switch has four positions. LO, and power goes through all three resistors, M1 and it bypasses one resistor and goes through the other two, M2, power bypasses two resistors and only goes through the third and HI, just like you said, the relay energizes and the entire resistor pack is bypassed with power going directly to motor.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
Above sounds like Manual Air. Module is block shaped sitting in the Evaporator Box with all of it innards cooled by a big heat sink.
Electronic amplifies low voltage signals from the Controls to vary Blower Speed based on Temp Settings, In and Outside Temp Sensors, except at Auto 90/60 wherein the Sensors are ignored and the Blower runs at Max.
If it's shutting on and off, check the Blower Motor Connector for burnt wiring meaning the terminals are dropping voltage, usually because the crimps have gone bad. You need to take apart the weatherpak to solder them back up or just solder in a new Connector.
Firewall 5 amp fuse simply protects a circuit that carries actual Blower Voltage; ie, what the Module has stepped up, back to the Controls. It doesn't protect the Blower Motor (which can draw up to 25 amps once they've aged a bit). Blower is on the Module Circuit which gets it's power from a fusible link. Should this 5 amp fuse open, you'll get high speed only and it can run with the ignition off. That doesn't sound like the problem here.
Electronic amplifies low voltage signals from the Controls to vary Blower Speed based on Temp Settings, In and Outside Temp Sensors, except at Auto 90/60 wherein the Sensors are ignored and the Blower runs at Max.
If it's shutting on and off, check the Blower Motor Connector for burnt wiring meaning the terminals are dropping voltage, usually because the crimps have gone bad. You need to take apart the weatherpak to solder them back up or just solder in a new Connector.
Firewall 5 amp fuse simply protects a circuit that carries actual Blower Voltage; ie, what the Module has stepped up, back to the Controls. It doesn't protect the Blower Motor (which can draw up to 25 amps once they've aged a bit). Blower is on the Module Circuit which gets it's power from a fusible link. Should this 5 amp fuse open, you'll get high speed only and it can run with the ignition off. That doesn't sound like the problem here.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 235
Likes: 9
From: Winter Garden Florida
Above sounds like Manual Air. Module is block shaped sitting in the Evaporator Box with all of it innards cooled by a big heat sink.
Electronic amplifies low voltage signals from the Controls to vary Blower Speed based on Temp Settings, In and Outside Temp Sensors, except at Auto 90/60 wherein the Sensors are ignored and the Blower runs at Max.
If it's shutting on and off, check the Blower Motor Connector for burnt wiring meaning the terminals are dropping voltage, usually because the crimps have gone bad. You need to take apart the weatherpak to solder them back up or just solder in a new Connector.
Firewall 5 amp fuse simply protects a circuit that carries actual Blower Voltage; ie, what the Module has stepped up, back to the Controls. It doesn't protect the Blower Motor (which can draw up to 25 amps once they've aged a bit). Blower is on the Module Circuit which gets it's power from a fusible link. Should this 5 amp fuse open, you'll get high speed only and it can run with the ignition off. That doesn't sound like the problem here.
Electronic amplifies low voltage signals from the Controls to vary Blower Speed based on Temp Settings, In and Outside Temp Sensors, except at Auto 90/60 wherein the Sensors are ignored and the Blower runs at Max.
If it's shutting on and off, check the Blower Motor Connector for burnt wiring meaning the terminals are dropping voltage, usually because the crimps have gone bad. You need to take apart the weatherpak to solder them back up or just solder in a new Connector.
Firewall 5 amp fuse simply protects a circuit that carries actual Blower Voltage; ie, what the Module has stepped up, back to the Controls. It doesn't protect the Blower Motor (which can draw up to 25 amps once they've aged a bit). Blower is on the Module Circuit which gets it's power from a fusible link. Should this 5 amp fuse open, you'll get high speed only and it can run with the ignition off. That doesn't sound like the problem here.
thanks,
John
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Rod, I'm always the nitpicker, I know, but I've had my Resistor Module out many times and there are actually three resistors.
The A/C Blower Control Switch has four positions. LO, and power goes through all three resistors, M1 and it bypasses one resistor and goes through the other two, M2, power bypasses two resistors and only goes through the third .
The A/C Blower Control Switch has four positions. LO, and power goes through all three resistors, M1 and it bypasses one resistor and goes through the other two, M2, power bypasses two resistors and only goes through the third .
Misread the C60 circuit diagram ,
Pg 4
http://members.shaw.ca/dankai/HVAC%20Electrical.pdf
Was only looking at the two speed positions on the fan speed switch ;not the resistor pack configuration
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Verdad Gallardo
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No problem Mate.
Yes. Sorry to the OP who had asked about C68. I didn't want to confuse anyone, but was replying to the section of Rod's post where he talks about C60. OP, Please disregard my previous post as it is not relevant to your situation.
Yes. Sorry to the OP who had asked about C68. I didn't want to confuse anyone, but was replying to the section of Rod's post where he talks about C60. OP, Please disregard my previous post as it is not relevant to your situation.