RayB_911

I ran Durametric scan on my car tonight. Haven't ran one since I took out of storage. Was surprised to see footwell flap motor fault.

Air Conditioning and Heater
Current Fault Codes
23: Footwell flap motor

Didn't think something like that would show up on scan.

Any chance this is related to my fuse blowing and are there any recommendations on what I do next?


Found this on previous thread here. https://rennlist.com/forums/964-foru...s-of-help.html

22, 23, 24, All drive links; present
31, 32

Visually inspect drive motors and wiring connectors. Connect wiring plug to another drive motor (drive motor on heater system or spare motor) to determine if motor is defective. If motor is not defective, try a different control unit (see note on page 1) to localize fault area. Replace defective part. Erase fault memory. Select drive link menu and operate drive motor several times. Read out fault memory again.

22, 23, 24, All drive links; not present
31, 32

Check wiring connectors on drive motors for corrosion and tight installation. Erase fault memory. Select drive link menu and operate drive motor several times. Read out fault memory again. If the same fault is displayed, replace drive motor.

Code Fault area
Repair steps

Important: Before activating fresh air flap motor, set controls to max. cold and A/C switch off (not pushed).

ToreB

It's not uncommon to have several stored servo faults over years of operation time. Servo faults can be intermittent, but faults can also be triggered by some hickup some time in the past.
I always test all servos by maneuvering the CCU controls several times, and also observing the movement. If one or more servos are faulty they almost always throw up a fault code within minutes of testing.
Cheers,
Tore

RayB_911

I'll probalby reset the fault and run those tests you have listed on your site, Tore. Appreciate the input again.

Is the footwel flap on the same Fuse #1 as the blowers?

Lorenfb

"Any chance this is related to my fuse blowing and are there any recommendations on what I do next?"

Any problem directly related to a servo or the CCU which causes a 25 amp
fuse to blow would totally destroy either element.

garrett1021

My 964 has a problem with its AC too (not trying to hijack here )

It ONLY blows hot, and only on one fan setting. I can rotate it to cold, or rotate it to hot, I can put fan speed on 0 or on max and nothing changes.

It always blows hot air. The P.O. put a bigger amp fuse in the ac slots (ill check back in exactly which ones later today) is this most likely because the previous amp fuses were blowing?

Now that's its getting towards summer, im needing that ac!!!

Ideas on what the problem is??

ToreB

I agree with you Loren, a 25A short circuit will fry the CCU and/or servo internals long before the fuse blows.
garrett1021, you could check out my HVAC DIY pages and find your fault. I would guess you are having one or more malfunctioning servo.
Cheers,
Tore

garrett1021

Thanks will do

RayB_911

Tore's site has been very helpful. I continue to learn but it is good to have advice from those who have gone before.

RayB_911

Did some more tests today. I disconnect electrical to AC and fuse still blew when I turned fan on. I ran thru Tore's tests. Footwell fault did not return and appears to be functioning with rear blower.

1: Mixer servos: Turn temperature **** to max and min, the mixer servos shall open and close
​Rear blower turns on at max temp (red). small pause as it starts up.

2: Fresh air servo: Turn temperature **** to min and max, the fresh air intake should open and close
​Rear blower turns off at blue. But sometimes goes off/on like a wave.

3: Footwell servo: Move lower slide **** to the right and left, the footwell servo should open and close
Cleared code, appears to work. Fault did not come back

4: Defrost servo: Move upper slide **** to the right and left, the defrost servo should open and close
​Appears to work

5: Main interior fans: Set to minimum temperature, turn fan speed to min and max. Fans should run accordingly
Min temp, AC off
0-fine,
1 fine but not real air flow?? Just air from rear blower?
2 fine, but still no no real air flow??
3, fan runs for a bit, then blows fuse.
​Ran scan, now new fault. Still 43 -rear blower motor Stage1. Have not had chance to search for it yet.

Cleared fault, did not turn fan on but started car and changed temps from min to max and back. Fault came back. The fan runs, it still some of that off/on.

RayB_911

Checked resister and plugs in for the rear blower. Cleaned contacts. Did not try to reset thermo Switch. Will keep trying things. I was trying to locate RHS blower power supply so I can pull it to see if the CCU will operate everything else. Been looking for pic of plug and location. Workshop manuals are not as helpful a as I hoped. I think I need to invest in the Bentley and/or Adrian's book for more help.

RayB_911

UPDATE

I disconnected the connector of the final stage amplifier and applied ground (momentarily) to pin 1 (BR/RE) and pin 6 (BR/GR) on the connector. Had a good arc on both, but no fans moved. nothing but some arcing. SO.... Fans bad or seized, correct?! CCU seems to be functioning.

Also, I think I am sure I don't have a low speed on the rear blower. I have taken out resistor, cleaned. Tried to reset whatever that is. No post actually tells you how to reset. I suspect it is bad. I put ohm meter on the two connectors and it is all over the place. Can't get good reading. I checked here and pelican for way to get low speed to run without resistor. If it works bypassed, then I can replace it. Tore had post that you can just bridge the connection? Thinking about trying.

Can rear lower low speed be affected by the CCU issues with the inept error fans?

It's too bad it's not working since the AC was serviced recently and blew real cold last year.

Thanks or the help.

RayB_911

I did bridge the resistor. One thing it stopped doing was the momentary pause it does each time it starts up. But it maintains one speed. So how would I know if it is high or low? I have lots to learn.

ToreB

High or low speed is controlled by the CCU using the rear blower relay. The rear fan runs on low speed if powered through the resistor, or on full speed if feeded with 12V.
The resistor reduce the motor current, thus low fan speed. There's no practical way of doing this in the 993 other than using the resistor. It gets very hot, and is therefore mounted inside the air duct for proper cooling.
The CCU has a feedback line from the blower motor, and will switch to high speed if nothing happens when trying low speed. This is a safety feature. If there's no connection when Ohming the two resistor terminals I recommend changing it. It might be possible to reset the thermoswitch by pressing it using a needle, but I have never seen a such a case, only failing thermoswitches. I therefore always change the resistor assembly.
Cheers,
Tore

xdecock

On my car, got the same trouble, the final stage is unplugged (to allow the oil cooler to still run) however, it blows instantly when i wire back my final stage, need to check if it's in the loom, the fans or the final stage itself.

Xavier.

RayB_911

Thanks. I will plan on replacing the resistor as soon as I get the interior fans sorted out.

Was my test with two fans correct and should pull the fans next?