CCU troubleshooting, anyone?
07-08-2004, 03:22 PM
#16
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#30 power is "always hot," even with the ignition shut off. Thus, your fans running with the key (and even CCU!) removed, if the circuit is completed.
Sounds like your FSR has failed. As I recall, they are rather expensive. Wonder if Loren offers rebuilt units? Or Otto's of Venice?
Sounds like your FSR has failed. As I recall, they are rather expensive. Wonder if Loren offers rebuilt units? Or Otto's of Venice?
07-08-2004, 08:12 PM
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I wonder if Loren offers rebuilt units too...
BTW Randall G., when I looked under that plastic cover under the hood, I saw the servos, but I didn't see anything that resembled the FSR photo you posted. Is the FSR dead center there or where exactly is it?
Apparently Otto is out til Monday and he's the only one that knows about parts.
BTW Randall G., when I looked under that plastic cover under the hood, I saw the servos, but I didn't see anything that resembled the FSR photo you posted. Is the FSR dead center there or where exactly is it?
Apparently Otto is out til Monday and he's the only one that knows about parts.
07-08-2004, 11:04 PM
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The FSR won't look exactly like the pictures I posted earlier, when installed. I believe it has a plastic cover over it, as shown in these pictures. It is towards the center of the car, near the base of the windshield:
07-09-2004, 01:37 AM
#19
The FSR is sealed unit with a potting compound and as such is not reparable.
It's very rare that this unit fails. I've only seen one bad unit over the years
and it was supposedly intermittent. Do an extensive troubleshooting effort
before concluding it as defective.
It's very rare that this unit fails. I've only seen one bad unit over the years
and it was supposedly intermittent. Do an extensive troubleshooting effort
before concluding it as defective.
07-09-2004, 04:10 PM
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It sounds like there is one FSR for both fans-correct? If I remove the FSR and the fans continue to run, how might #30, other than through the FSRs, be applied to the fan motors?
If, on the other hand, we remove the FSR and the fans stop, but we assume the FSR is good, what is the source of the control signal to the FSR that is causing the fans to run?
If the control signal is from the CCU, why did the fans continue to run with the CCU removed? When the system is working properly, does the CCU need to be installed to turn the fans off?
If, on the other hand, we remove the FSR and the fans stop, but we assume the FSR is good, what is the source of the control signal to the FSR that is causing the fans to run?
If the control signal is from the CCU, why did the fans continue to run with the CCU removed? When the system is working properly, does the CCU need to be installed to turn the fans off?
07-10-2004, 04:47 AM
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>It sounds like there is one FSR for both fans-correct?
Correct.
>If I remove the FSR and the fans continue to run, how might #30, other than through the FSRs, be applied to the fan motors?
Only if you have a short to ground, between the fans and the FSR, could the fans run with the FSR removed. In which case, I would expect your fans to be running very fast.
Remember, the 12V power goes through the fans first, before going to the FSR. The current path: 1) fused power from #30; 2) fans; 3) FSR; 4) ground.
>If, on the other hand, we remove the FSR and the fans stop, but we assume the FSR is good, what is the source of the control signal to the FSR that is causing the fans to run?
The fans will stop with the FSR removed, short of having a short to ground, as described above.
The CCU provides the control signal to the FSR, which is converted to a resistance between the fans and ground.
>If the control signal is from the CCU, why did the fans continue to run with the CCU removed?
The assumption is the FSR has failed in a non-open circuit position. Thus, giving the fan power a path to ground. With the ignition off, the FSR is supposed to open the fan's current path. Looks like that isn't happening with your FSR.
>When the system is working properly, does the CCU need to be installed to turn the fans off?
To be honest, I haven't tested this, and have to defer to what Loren wrote above (fan running with CCU removed indicates a bad FSR). Anyway, I suspect the CCU isn't needed to turn the fans off. One way to know for certain is to install a friend's CCU long enough to verify your problem doesn't go away. That's what I did for a friend last year, when he had the same problem as yourself (he later gave me the bad FSR to play with, the one in the pictures).
Hope this helps, and keep us posted on what you find.
Correct.
>If I remove the FSR and the fans continue to run, how might #30, other than through the FSRs, be applied to the fan motors?
Only if you have a short to ground, between the fans and the FSR, could the fans run with the FSR removed. In which case, I would expect your fans to be running very fast.
Remember, the 12V power goes through the fans first, before going to the FSR. The current path: 1) fused power from #30; 2) fans; 3) FSR; 4) ground.
>If, on the other hand, we remove the FSR and the fans stop, but we assume the FSR is good, what is the source of the control signal to the FSR that is causing the fans to run?
The fans will stop with the FSR removed, short of having a short to ground, as described above.
The CCU provides the control signal to the FSR, which is converted to a resistance between the fans and ground.
>If the control signal is from the CCU, why did the fans continue to run with the CCU removed?
The assumption is the FSR has failed in a non-open circuit position. Thus, giving the fan power a path to ground. With the ignition off, the FSR is supposed to open the fan's current path. Looks like that isn't happening with your FSR.
>When the system is working properly, does the CCU need to be installed to turn the fans off?
To be honest, I haven't tested this, and have to defer to what Loren wrote above (fan running with CCU removed indicates a bad FSR). Anyway, I suspect the CCU isn't needed to turn the fans off. One way to know for certain is to install a friend's CCU long enough to verify your problem doesn't go away. That's what I did for a friend last year, when he had the same problem as yourself (he later gave me the bad FSR to play with, the one in the pictures).
Hope this helps, and keep us posted on what you find.
07-12-2004, 05:53 PM
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Randall G.--
do you have a part number for the FSR your friend gave you? And also, if you were playing around with it, did you happen to get resistance readings to verify the short? What vendor did you use to buy the new part?
Finally, is there another name for that part?
do you have a part number for the FSR your friend gave you? And also, if you were playing around with it, did you happen to get resistance readings to verify the short? What vendor did you use to buy the new part?
Finally, is there another name for that part?
07-12-2004, 11:47 PM
#23
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Hey BlackCab,
>do you have a part number for the FSR your friend gave you?
The part number is 964 624 010 02.
>And also, if you were playing around with it, did you happen to get resistance readings to verify the short?
He ordered the replacement unit based on a process of elimination, without measuring the FSR resistance values. That said, I did play with the terminals I thought would show a blatantly low resistance, after he gave it to me. Didn't find one. Though, one pair of terminals (from fan power-in to ground-out) had a resistance significantly lower than the other--110 Kohms, as compared to 3 Mohms. A 110 Kohm resistance isn't low enough to cause a current leakage worth worrying about (12V/110 Kohm = 0.11 mA). Without a schematic of the innards, I really didn't know what I was measuring across (transistors?). Things could be different with power supplied to the unit. Anyway, I'm guessing the side with the much-lower resistance was at fault (electronics repair is not my forte).
>What vendor did you use to buy the new part?
My buddy wound up taking the car to his shop to install the part--we stopped short of taking his FSR out of his car in my garage. The shop provided the part, and charged him $250.
>Finally, is there another name for that part?
No, not really. The wiring diagram calls it "Blower Final Stage," PET calls it "regulator (final stage) for blower."
Hope this helps, and good luck!
>do you have a part number for the FSR your friend gave you?
The part number is 964 624 010 02.
>And also, if you were playing around with it, did you happen to get resistance readings to verify the short?
He ordered the replacement unit based on a process of elimination, without measuring the FSR resistance values. That said, I did play with the terminals I thought would show a blatantly low resistance, after he gave it to me. Didn't find one. Though, one pair of terminals (from fan power-in to ground-out) had a resistance significantly lower than the other--110 Kohms, as compared to 3 Mohms. A 110 Kohm resistance isn't low enough to cause a current leakage worth worrying about (12V/110 Kohm = 0.11 mA). Without a schematic of the innards, I really didn't know what I was measuring across (transistors?). Things could be different with power supplied to the unit. Anyway, I'm guessing the side with the much-lower resistance was at fault (electronics repair is not my forte).
>What vendor did you use to buy the new part?
My buddy wound up taking the car to his shop to install the part--we stopped short of taking his FSR out of his car in my garage. The shop provided the part, and charged him $250.
>Finally, is there another name for that part?
No, not really. The wiring diagram calls it "Blower Final Stage," PET calls it "regulator (final stage) for blower."
Hope this helps, and good luck!
Last edited by Randall G.; 07-13-2004 at 12:30 AM.
07-16-2004, 10:04 PM
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Well, looking at the FSR, the transistors that go to pins 6 and 7 have resistances of about 11 ohms. The other two transistors have resistances of about 8.5 Megaohms leading me to believe that the FSR is bad and that those first two transistors have a short.
Anyone feel the need to pull me off the path of inaccurate conclusions or does that sound like a reasonable interpretation?
Thanks again for all the advice. Some pretty impressive people here...
Anyone feel the need to pull me off the path of inaccurate conclusions or does that sound like a reasonable interpretation?
Thanks again for all the advice. Some pretty impressive people here...
07-16-2004, 11:56 PM
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Hey BlackCab,
On the unit given to me, pins #2 & #7 are shunted (0.2 ohms). Which is okay, because they both go to ground (the fan "goes-out").
#1 to 2/7 was 110 Kohms, regardless of probe polarity. #1 is the "goes-in" from the left fan. Perhaps this is analogous to your "other two" transistors.
#6 to 2/7 was 3 Mohms or off-scale high high, depending on probe polarity. #6 is the "goes-in" from the right-fan.
Anyway, since #6 to #7 represents a current path from a fan (and its power) to ground, 11 ohms sounds like a smoking gun to me.
On the unit given to me, pins #2 & #7 are shunted (0.2 ohms). Which is okay, because they both go to ground (the fan "goes-out").
#1 to 2/7 was 110 Kohms, regardless of probe polarity. #1 is the "goes-in" from the left fan. Perhaps this is analogous to your "other two" transistors.
#6 to 2/7 was 3 Mohms or off-scale high high, depending on probe polarity. #6 is the "goes-in" from the right-fan.
Anyway, since #6 to #7 represents a current path from a fan (and its power) to ground, 11 ohms sounds like a smoking gun to me.
Last edited by Randall G.; 07-17-2004 at 01:07 AM.
07-17-2004, 01:28 PM
#26
The pins descriptions are as follows:
1. 2/7 grounds - connected internally
2. 3/5 inputs
3. 4/8 current sense feedback
4. 1/6 output current sinks (collector/drain of output transistors)
An easy test for the outputs is to ground pins 2/7 and use a test light
connected to +12v and touch each pin (1/6). If the light glows, that
pin is shorted to ground. With no input signal, each output (1/6) should
be "open". By using a 1K ohm resistor to +12v on either input (3/5),
each transistor can be turned "on" causing the test light to glow.
The actual motor control amplifier is in the CCU, which "drives" the
two power transistors on the FSR. The two feedbacks are used to
limit the transistor currents and regulate the fan speed (via currents).
1. 2/7 grounds - connected internally
2. 3/5 inputs
3. 4/8 current sense feedback
4. 1/6 output current sinks (collector/drain of output transistors)
An easy test for the outputs is to ground pins 2/7 and use a test light
connected to +12v and touch each pin (1/6). If the light glows, that
pin is shorted to ground. With no input signal, each output (1/6) should
be "open". By using a 1K ohm resistor to +12v on either input (3/5),
each transistor can be turned "on" causing the test light to glow.
The actual motor control amplifier is in the CCU, which "drives" the
two power transistors on the FSR. The two feedbacks are used to
limit the transistor currents and regulate the fan speed (via currents).
Last edited by Lorenfb; 07-17-2004 at 01:56 PM.
07-22-2004, 01:55 AM
#27
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well, the good news is that the FSR is fixed with a couple new transistors and the fan is not running when it is not supposed to. I was ecstatic, I'm telling you--first time in three months to have silence when the car is off without pulling the fuse out. Anyway, I was remembering that before that, if the A/C had been running a while, it would sound like there was a cricket in the car. Some sort of chirpping noise. I hope it wasn't signalling a problem with the fans that ultimately caused those transistors to go bad. Hopefully you won't hear from me again on this issue. Hopefully my last words on this topic will be thanks so much for all your help. You guys are the best... 
