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acme
Imola


Joined: 22 Oct 2007
Posts: 832



PostPosted: Mon Jan 14, 2019 5:39 pm    Post subject: Heating issues Reply with quote

Inevitably after ten years of ownership you get to know your car and what is/isn't normal.

After about three weeks of not using it over Christmas the battery was completely flat, to the extent that I couldn't unlock via the fob - which has never happened before.

Charge the battery and all's fine.....except the heating/AC doesn't seem to be as powerful as before, either on the regular fan speeds, or most definitely on the large snowflake/full speed of the AC. The AC is working as I can see the clutch spinning up on the compressor.

For a while I've noticed small black particles on the dash top, whenever I use the car I run the AC and always run it for a little while on max to make sure it's all lubricated etc - so I thought perhaps some of the 'fluff' was just old stuff coming out.

Of the vents below the windscreen there's almost nothing coming out of the right hand one, though there is for the right hand one near the door below the steering wheel.

I can hear the blower motor in the rear working, and on position four I can hear air rushing in under both back corners under the bonnet.

So, any ideas, is it anything to do with the battery going (very) flat, or have the mice been nibbling at something - found bait under the engine area.....

I'm thinking stuck/knackered flap/servo?

Cheers
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Endoman
Barcelona


Joined: 11 Apr 2011
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Location: Bolton U.K.


PostPosted: Mon Jan 14, 2019 5:44 pm    Post subject: Reply with quote

Tore is your man for all things hvac (and lights)
https://www.bergvillfx.com/porschehvac1
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AndyS
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PostPosted: Mon Jan 14, 2019 8:34 pm    Post subject: Reply with quote

Interesting. Mine was stood for close to 10 months when in at Ninemeister for the paint job - and when that came back I had small black particles blowing on to the dash top.
I figured this was due to the crap accumulated during the work - and it stopped after a short period, so I just forgot about it.
Would be nice to know more.....
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Andy
1996 Polar Silver 993 Coupe - AKA 'the money pit'
A Class AMG & Golf TDi for the daily

 
  
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ToreB
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Joined: 13 May 2010
Posts: 575
Location: Oslo, Norway


PostPosted: Tue Jan 15, 2019 6:34 am    Post subject: Reply with quote

Endoman, thank you.
I would start with testing all HVAC servos and fans, and then onto checking for current drains.

HVAC:
https://www.bergvillfx.com/porschehvac1

Current:
https://www.bergvillfx.com/porsche-964-993-battery-current-measurements/

Cheers,
Tore
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'95 993 C4

Bergvill F/X
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Tobesetc
Albert Park


Joined: 02 Jun 2014
Posts: 1512
Location: West London, UK


PostPosted: Tue Jan 15, 2019 8:04 am    Post subject: Reply with quote

When my system failed I had fairly large bits of very fine blacks film blow out of the vent as well as the little bits. Here's a pic. It looks like the top laminate from vinyl, but can't be sure.

Clearly the lining somewhere breaks down. I suggest that the parts that blew out of mine would be large enough to block (or severely restrict flow through ) pipes if they got stuck across a pipe.

Never heard anyone explain exactly where this stuff comes from and how to remove it rather than just await it disintegrating and blowing through.
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ToreB
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PostPosted: Tue Jan 15, 2019 8:47 am    Post subject: Reply with quote

This is most probably the thin covering on the foam on the Defrost vent flap. This flap is placed centrally in the air box, at the outlet for the two centre vents.
See the pic below, slightly wrinkled foam covering.

Cheers,
Tore
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Tobesetc
Albert Park


Joined: 02 Jun 2014
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Location: West London, UK


PostPosted: Tue Jan 15, 2019 8:56 am    Post subject: Reply with quote

So, if the foam is supposed to have a thin covering to prevent air passing through it... and that thin covering gone... what happens? Surely the air con won't work as well (or they wouldn't put the stuff there!)

Can this be easily replaced, at next service, perhaps?
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ToreB
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PostPosted: Tue Jan 15, 2019 9:06 am    Post subject: Reply with quote

The air box must be taken out of the car to replace this, and I would estimate this to be a 5-10 hour job. I guess the foam has several purposes, possibly to dampen air flow noise and to ensure proper closing of the flap.
I would think that removing the covering will have little impact on air flow/noise, especially taking into account the work needed to replace this.
However, if you ever are to replace your evaporator, and the air box is out anyway, I would think of replacing the foam.
Cheers,
Tore
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acme
Imola


Joined: 22 Oct 2007
Posts: 832



PostPosted: Tue Jan 15, 2019 2:46 pm    Post subject: Reply with quote

Many thanks for the replies Gents, appreciated Thumb

Thanks too Tore, I shall check these out.

I'm assuming when turning max/min heat/fan speed and there's little change on the right handside it means servo issue.....I shall investigate further.

I guess the question is, if it is these how can you change Question
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ToreB
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PostPosted: Tue Jan 15, 2019 4:10 pm    Post subject: Reply with quote

Test all servos first, and we'll take it from there.
HVAC servo change is relatively easy, depending on which one you need to fix.
Cheers,
Tore
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acme
Imola


Joined: 22 Oct 2007
Posts: 832



PostPosted: Tue Jan 15, 2019 4:26 pm    Post subject: Reply with quote

Thanks Tore, appreciated Thumb

Gavin
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Citori
Kyalami


Joined: 09 Oct 2010
Posts: 1825
Location: Rural Essex..

1996 Porsche 993 Carrera 2

PostPosted: Tue Jan 15, 2019 8:38 pm    Post subject: Reply with quote

ToreB
Can you help us?
When you run the test of the ECU outputs using your OBD lead and scantool.
What is each test doing?
ie, if it's activating 2, what is it actually testing?
I'm sure I had a list of these tests at one time, but I can't find it anywhere.
Do you have a list?
Thanks.
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Previously enjoyed Porsche:
1996 C2 Coupe.
1983 911 Carrera Targa Sport.
1981 911SC Sport.
1978 911SC.
1970 911E.

I have CDO. It’s like OCD, but the letters are in alphabetical order, LIKE THEY ARE SUPPOSED TO BE..

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ToreB
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Joined: 13 May 2010
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PostPosted: Tue Jan 15, 2019 8:55 pm    Post subject: Reply with quote

I made this list years ago:

Seq. (start): Servo 4; OPEN, Left mixing flap (controls hot & cold air mixing) (993: in the footwell)
Seq. 1: Servo 4; CLOSE
Seq. 2: Servo 2; OPEN, Right mixing flap (controls hot & cold air mixing) (993: in the footwell)
Seq. 3: Servo 2; CLOSE
Seq. 4: Servo 1; OPEN, Defroster flap (center nozzle) right servo in luggage comp. with white horizontal rotating axle
Seq. 5: Servo 1; CLOSE
Seq. 6: Servo 5; OPEN, Footwell flap (leftmost servo in luggage comp.)
Seq. 7: Servo 5; CLOSE
Seq. 8: Servo 3; OPEN, Fresh air flap (middle servo in luggage comp.)
Seq. 9: Servo 3; CLOSE, “
Seq. 10: A/C radiator fan; Low speed, (left front fender behind head light)
Seq. 11: A/C radiator fan; High speed
Seq. 12: Oil radiator fan; Low speed, (right front fender behind head light)
Seq. 13: Oil radiator fan; High speed
Seq. 14: Primary blower fan; Low, (engine bay, above left side of engine)
Seq. 15: Primary blower fan; High
Seq. 16: Secondary blower fan; (dashboard; Left side)
Seq. 17: Secondary blower fan; (dashboard; Right side)
Seq. 18: A/C radiator fan; Low speed
Seq. 19: no reaction (resirc flap valve?)
Seq. 20: no reaction


The servo tests are meant for adjusting the mechanical arms, and does not test if the servo works or has the typical damage. Test movement use brute force and not position feedback as in normal CCU operation.
Cheers,
Tore
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Citori
Kyalami


Joined: 09 Oct 2010
Posts: 1825
Location: Rural Essex..

1996 Porsche 993 Carrera 2

PostPosted: Tue Jan 15, 2019 9:10 pm    Post subject: Reply with quote

Thanks for that Tore. That list is perfect.
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Previously enjoyed Porsche:
1996 C2 Coupe.
1983 911 Carrera Targa Sport.
1981 911SC Sport.
1978 911SC.
1970 911E.

I have CDO. It’s like OCD, but the letters are in alphabetical order, LIKE THEY ARE SUPPOSED TO BE..

Aircooled or nothin....
 
  
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acme
Imola


Joined: 22 Oct 2007
Posts: 832



PostPosted: Wed Jan 16, 2019 4:18 pm    Post subject: Reply with quote

Many thanks Tore for your help, much appreciated Thumb

Initially the below codes came up. These were cleared and then we went through the Climate Control tests, all appearing to be fine, this we did a couple of times, seemingly without fault.

43 - Rear blower motor speed 1
44 - Rear blower motor speed 2
45 - Inside sensor blower motor

Getting back in the car and firing her up all seems to be well; AC max is now as it was, and the regular 4 speed fan positions are also as they were. Likewise the right hand dash vent now has air coming through it.

I can only conclude the battery going as flat as it did caused the error codes?

Lesson learnt, the solar trickle charger which seems fine in the summer is useless in winter frustrated
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ToreB
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PostPosted: Wed Jan 16, 2019 5:50 pm    Post subject: Reply with quote

Good job!
A flat battery will probably not cause any CCU faults.
I always note and clear all codes, then operate all CCU knobs for a minute or so, then re-read faults.

I'd keep an eye on the rear fan, it has obviously not worked in any of the two speeds at one time in the past. I mostly see both code appear when the motor has stalled due to bad bearings, and blown the fuse.
Fault code Speed 1 fires if the rear fan low speed resistor is shot. I change 10-20 of these resistors per year.

It is not uncommon to see fault codes on the CCU fan. (Inside Sensor blower) The fan bearings and magnets wear out, and it will not start. A road bump may start it. However, I always advise to change the fan when the fault code appear. Be sure to be safely seated well when you hear the price. Part # 964 659 148 02. (about 300 euro)
The fan is imperative for the unit to be able to sample the cabin temperature.
Cheers,
Tore
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acme
Imola


Joined: 22 Oct 2007
Posts: 832



PostPosted: Wed Jan 16, 2019 7:35 pm    Post subject: Reply with quote

ToreB wrote:
Good job!
A flat battery will probably not cause any CCU faults.
I always note and clear all codes, then operate all CCU knobs for a minute or so, then re-read faults.

I'd keep an eye on the rear fan, it has obviously not worked in any of the two speeds at one time in the past. I mostly see both code appear when the motor has stalled due to bad bearings, and blown the fuse.
Fault code Speed 1 fires if the rear fan low speed resistor is shot. I change 10-20 of these resistors per year.

It is not uncommon to see fault codes on the CCU fan. (Inside Sensor blower) The fan bearings and magnets wear out, and it will not start. A road bump may start it. However, I always advise to change the fan when the fault code appear. Be sure to be safely seated well when you hear the price. Part # 964 659 148 02. (about 300 euro)
The fan is imperative for the unit to be able to sample the cabin temperature.
Cheers,
Tore


Hi Tore,

Have to say I was somewhat relieved, let's hope it remains!

The car was in storage on and off for two years whilst I had a new garage built and I suspect despite being professional storage, and a new Bosch S5 it's probably been left to die one too many times in the past couple of years!

Seems sensible I re-read the codes now I've got an hour or so usage since we last ran through them to see if I've any codes etc.

Occasionally the max AC button won't go on, though it's been fine for a couple of years - & given that I had to have the condensor replaced two months after I got the car 10 years ago I always run the AC, and always for a few minutes in max mode too.

We replaced the front ballast resistor on the oil rad a few years back, so I'm guessing it's similar.

Ouch, seems another to keep an eye on - is it hard to change once you've got over the shock of the (porsche tax) price?

Thanks again Thumb

Gavin
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