Heater bypass tube?
10-11-2012, 03:25 PM
#76
Cheers anto1150 and Babalouie! 
Bertrand, I have a question regarding this post:
https://rennlist.com/forums/9832762-post52.html
What is the fooling resisitor? If no fooling resistor is connected and I use the jumper method, will there be no drain?
Bertrand, I have a question regarding this post:
https://rennlist.com/forums/9832762-post52.html
What is the fooling resisitor? If no fooling resistor is connected and I use the jumper method, will there be no drain?
10-11-2012, 07:35 PM
#77
Burning Brakes
I think the "fooling" resistor is another mod: https://rennlist.com/forums/964-foru...ypass-box.html
Which is different in philosophy to the one-wire method
Which is different in philosophy to the one-wire method
10-12-2012, 03:49 AM
#78
The 'fooling resistor' was a method implemented by (I think) John in the UK (www.porsche964.co.uk - inactive now) on a 1991.
The idea was to replace the blower-motor by a resistor. So instead of having an electric motor connected to the relay, you had a power resistor pulling the same amount of current when the CCU decided to switch on the (now removed) electric motor.
Now THAT was working fine on 1991+ cars. But not on 1989-90. So people tried that and then did an ADDITIONAL mod: The relay-socket wire.
What they did not realize, was that by doing so, they were powering the power-resistor (the fooling-resistor) all the time, even when the ignition was off: hence battery drain in a say 5 ohms resistor = 2.4A: in 33H the 80Ah. battery would be absolutely empty.
So 3 methods so far (see post 70):
The coil-wire method: No drain but requiring some work
The socket-wire method: Very easy but adding 0.4 ma drain to the standard drain (50 to 100mA from what I have seen on the net) - According to Cartwheel in post 55, that's not noticeable.
The CCu-wire method: Clean, no drain, but requiring to move out the bloody thing...
It all depends on what you prefer in terms of balance of reversibility/efficiency/ease of installation.
When my blower-motor packed, I used the socket-wire method (or jumper) because I wanted it to be reversible quickly by the time I received the new motor.
If I had to do it permanently, I would use 'The CCu-wire method'.
If I had to do it permanently but safely reversible, 'The coil-wire method'
Because it would bug me to add even a tiny-weeny bit of drain.
The idea was to replace the blower-motor by a resistor. So instead of having an electric motor connected to the relay, you had a power resistor pulling the same amount of current when the CCU decided to switch on the (now removed) electric motor.
Now THAT was working fine on 1991+ cars. But not on 1989-90. So people tried that and then did an ADDITIONAL mod: The relay-socket wire.
What they did not realize, was that by doing so, they were powering the power-resistor (the fooling-resistor) all the time, even when the ignition was off: hence battery drain in a say 5 ohms resistor = 2.4A: in 33H the 80Ah. battery would be absolutely empty.
So 3 methods so far (see post 70):
The coil-wire method: No drain but requiring some work
The socket-wire method: Very easy but adding 0.4 ma drain to the standard drain (50 to 100mA from what I have seen on the net) - According to Cartwheel in post 55, that's not noticeable.
The CCu-wire method: Clean, no drain, but requiring to move out the bloody thing...
It all depends on what you prefer in terms of balance of reversibility/efficiency/ease of installation.
When my blower-motor packed, I used the socket-wire method (or jumper) because I wanted it to be reversible quickly by the time I received the new motor.
If I had to do it permanently, I would use 'The CCu-wire method'.
If I had to do it permanently but safely reversible, 'The coil-wire method'
Because it would bug me to add even a tiny-weeny bit of drain.
Last edited by Bertrand; 10-12-2012 at 05:14 AM. Reason: precision
10-12-2012, 11:26 AM
#79
The 'fooling resistor' was a method implemented by (I think) John in the UK (www.porsche964.co.uk - inactive now) on a 1991.
The idea was to replace the blower-motor by a resistor. So instead of having an electric motor connected to the relay, you had a power resistor pulling the same amount of current when the CCU decided to switch on the (now removed) electric motor.
Now THAT was working fine on 1991+ cars. But not on 1989-90. So people tried that and then did an ADDITIONAL mod: The relay-socket wire.
What they did not realize, was that by doing so, they were powering the power-resistor (the fooling-resistor) all the time, even when the ignition was off: hence battery drain in a say 5 ohms resistor = 2.4A: in 33H the 80Ah. battery would be absolutely empty.
So 3 methods so far (see post 70):
The coil-wire method: No drain but requiring some work
The socket-wire method: Very easy but adding 0.4 ma drain to the standard drain (50 to 100mA from what I have seen on the net) - According to Cartwheel in post 55, that's not noticeable.
The CCu-wire method: Clean, no drain, but requiring to move out the bloody thing...
It all depends on what you prefer in terms of balance of reversibility/efficiency/ease of installation.
When my blower-motor packed, I used the socket-wire method (or jumper) because I wanted it to be reversible quickly by the time I received the new motor.
If I had to do it permanently, I would use 'The CCu-wire method'.
If I had to do it permanently but safely reversible, 'The coil-wire method'
Because it would bug me to add even a tiny-weeny bit of drain.
The idea was to replace the blower-motor by a resistor. So instead of having an electric motor connected to the relay, you had a power resistor pulling the same amount of current when the CCU decided to switch on the (now removed) electric motor.
Now THAT was working fine on 1991+ cars. But not on 1989-90. So people tried that and then did an ADDITIONAL mod: The relay-socket wire.
What they did not realize, was that by doing so, they were powering the power-resistor (the fooling-resistor) all the time, even when the ignition was off: hence battery drain in a say 5 ohms resistor = 2.4A: in 33H the 80Ah. battery would be absolutely empty.
So 3 methods so far (see post 70):
The coil-wire method: No drain but requiring some work
The socket-wire method: Very easy but adding 0.4 ma drain to the standard drain (50 to 100mA from what I have seen on the net) - According to Cartwheel in post 55, that's not noticeable.
The CCu-wire method: Clean, no drain, but requiring to move out the bloody thing...
It all depends on what you prefer in terms of balance of reversibility/efficiency/ease of installation.
When my blower-motor packed, I used the socket-wire method (or jumper) because I wanted it to be reversible quickly by the time I received the new motor.
If I had to do it permanently, I would use 'The CCu-wire method'.
If I had to do it permanently but safely reversible, 'The coil-wire method'
Because it would bug me to add even a tiny-weeny bit of drain.
02-19-2013, 08:58 AM
#80
Nordschleife Master
Quick question for those that have re-wired the relay connector block with a jumper wire. Is there a specific size of spade connector needed for the wire? The spades I have are 6 mm wide and look too big to plug into the block.
02-26-2013, 04:31 AM
#81
You can measure the spades on the relay and buy something similar or a bit smaller. As long as it contacts and does not come loose, it's fine.
If you really want something neat, you can find a Audi/VW relay of similar size, remove the spades you do not use, open the cover and replace the relay mechanism by the wire between the relevant blades.
(And good luck to the next owner to find out the mod....)
If you really want something neat, you can find a Audi/VW relay of similar size, remove the spades you do not use, open the cover and replace the relay mechanism by the wire between the relevant blades.
(And good luck to the next owner to find out the mod....)
Last edited by Bertrand; 02-27-2013 at 03:39 AM.
05-19-2013, 09:15 AM
#82
Three Wheelin'
Hi Guys,
sorry to bring this thread up again, I have fitted the fan bypass for about 6 months , with the wiring advise above same as Anto & Babalouie (see pictures) ; I am recently experience a few issues with the fans ;
they sometime not working, or working when temperature button is turned on full cold, yesterday it was raining a lot , I wanted to set the temperature to 22/24, when I set the fans at 2/3 but they were not working , until I lower the temperature to complitly cold, in another words,
if I set the fans to 4 , I turn the buttons to full cold the fan are working full blast, and if I turn temperature to full hot the fan are stop working ?!
just wander the issue is the wiring ? the car is from 1992,
thanks for your comments !
sorry to bring this thread up again, I have fitted the fan bypass for about 6 months , with the wiring advise above same as Anto & Babalouie (see pictures) ; I am recently experience a few issues with the fans ;
they sometime not working, or working when temperature button is turned on full cold, yesterday it was raining a lot , I wanted to set the temperature to 22/24, when I set the fans at 2/3 but they were not working , until I lower the temperature to complitly cold, in another words,
if I set the fans to 4 , I turn the buttons to full cold the fan are working full blast, and if I turn temperature to full hot the fan are stop working ?!
just wander the issue is the wiring ? the car is from 1992,
thanks for your comments !
Last edited by kos11-12; 05-19-2013 at 09:49 AM.
05-19-2013, 12:31 PM
#84
Three Wheelin'
Can't believe myself, I find both wires loose from the conections and the 5 A fuse melted,
Replace the connections and fuse and it's back to normal and working perfect
Replace the connections and fuse and it's back to normal and working perfect
05-20-2013, 02:01 PM
#86
Three Wheelin'
yes I think so, the wire I used was quite thick, I did not crush it well to the connectors they were loose (the ones before & after the fuse)....
I can't believe my mistake, believe it not, I have rewired 3 of my classic motorcycles in the past that are working perfectly....
I can't believe my mistake, believe it not, I have rewired 3 of my classic motorcycles in the past that are working perfectly....
08-11-2013, 07:56 PM
#87
Question - to actually do this mod on a 1992 RS car...without A/C, would I still be able to get hot air inside? Gets cold here in the winters (UK and Europe).
Yes contrary to what is written: RS cars did not have this mod, only Cup cars.
Yes contrary to what is written: RS cars did not have this mod, only Cup cars.
08-11-2013, 08:35 PM
#88
Burning Brakes
I should think so...with the bypass, the hot air would be driven by the engine fan, then pulled into the cabin by the dash ventilation fans. Works just fine with the a/c off.
08-12-2013, 06:40 AM
#89
And is there a definite methodology to trick the CCU and make sure the inside front fan still works? Betrand's method maybe
From my research here, i haven't seen a simple clear methodology with clear instructions on what to exactly do that 100% works.
I cannot imagine installing this pipe and not having any air flow at all in the cabin - wife would go nuts without heating in the winter.
I also have found these instructions from one of the sellers: http://www.porscheshop.co.uk/bcatalo...pe-964-993.pdf
Would this method get me the "faulty" signal? Or do i also need to apply the Betrand's method?
From my research here, i haven't seen a simple clear methodology with clear instructions on what to exactly do that 100% works.
I cannot imagine installing this pipe and not having any air flow at all in the cabin - wife would go nuts without heating in the winter.
I also have found these instructions from one of the sellers: http://www.porscheshop.co.uk/bcatalo...pe-964-993.pdf
Would this method get me the "faulty" signal? Or do i also need to apply the Betrand's method?
Last edited by 911Thrasher; 08-12-2013 at 07:02 AM.
08-12-2013, 07:43 AM
#90
Racer
Join Date: Jul 2002
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Hi Thrasher , the standard 964RS Lightweight ( carpet ) has a proper heating system with rear blower fan and temp control installed . People strip them out to save weight eg for racing , so if you have a heater bypass installed then its not standard. PM me if you need more info , I live local .