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That particular shop has made that "993-flashed 964 CCU" claim on several occasions and I took that claim straight to Tore who quickly called it a load of BS.
The text shown in the initial post is pure BS.
There are several software versions of the 964/993 Climate Control Units, all made for use in the vehicle model in question. So the question of benefit of a software upgrade depends on what you have got.
The short version is that the early 964 CCU software version H00/H01 are the only ones that might benefit of an upgrade to the later 964 versions. The main difference are the enhanced OBD functions, (not really noticeable or usable for the driver) and that the two main blowers are possible to regulate to zero speed. (vH00/H01 fans never stop completely, speed setting 0 and 1 are the same) I would question the latter too, it is difficult to notice by the user.
In my opinion, the work and cost involved to change the CCU microprocessor board/memory chip compared to the benefit does not match.
Using a 993 software version or CCU in a 964 needs several modifications to the hardware, since there were many changes of the HVAC system in the 993. Examples are the added rear air selector valve, vacuum operated resirculation flap and the outside temp sensor.
The initial post suggests that a 993 software "makes all the difference", which is BS. There are really no user-noticeable differences between the late 964 units and the 993 units.
Cheers,
Tore
The initial post suggests that a 993 software "makes all the difference", which is BS. There are really no user-noticeable differences between the late 964 units and the 993 units.
Cheers,
Tore
The text shown in the initial post is pure BS.
There are several software versions of the 964/993 Climate Control Units, all made for use in the vehicle model in question. So the question of benefit of a software upgrade depends on what you have got.
The short version is that the early 964 CCU software version H00/H01 are the only ones that might benefit of an upgrade to the later 964 versions. The main difference are the enhanced OBD functions, (not really noticeable or usable for the driver) and that the two main blowers are possible to regulate to zero speed. (vH00/H01 fans never stop completely, speed setting 0 and 1 are the same) I would question the latter too, it is difficult to notice by the user.
In my opinion, the work and cost involved to change the CCU microprocessor board/memory chip compared to the benefit does not match.
Using a 993 software version or CCU in a 964 needs several modifications to the hardware, since there were many changes of the HVAC system in the 993. Examples are the added rear air selector valve, vacuum operated resirculation flap and the outside temp sensor.
The initial post suggests that a 993 software "makes all the difference", which is BS. There are really no user-noticeable differences between the late 964 units and the 993 units.
Cheers,
Tore
Originally Posted by Lorenfb
It's as simple as that!
So question for you two: I've a 91 with a well functioning CCU, but it would be nice to be able to fully shut off the fans. To add that capability, is that a significant change?
So question for you two: I've a 91 with a well functioning CCU, but it would be nice to be able to fully shut off the fans. To add that capability, is that a significant change?
Why, very little air at those settings anyway? To make that mod requires removing the processor chip from the circuit and re-flashing it.
It may be that the early 964 CCU processor has a mask ROM, i.e. not re-flashable. Once re-flashed, the processor needs to be re-soldered
to the circuit board, which typically results in reliability problems, e.g. the "performance" mod of the '96 993 DME ECU. It's laughable that
someone would even consider having that done given the excellent reliability of the 964/993 CCU and its overall functionality for a very
minor change, i.e. no mention of any significant benefits.
Why, very little air at those settings anyway? To make that mod requires removing the processor chip from the circuit and re-flashing it.
It may be that the early 964 CCU processor has a mask ROM, i.e. not re-flashable. Once re-flashed, the processor needs to be re-soldered
to the circuit board, which typically results in reliability problems, e.g. the "performance" mod of the '96 993 DME ECU. It's laughable that
someone would even consider having that done given the excellent reliability of the 964/993 CCU and its overall functionality for a very
minor change, i.e. no mention of any significant benefits.
So not worth it :-)
Why? So the fan isn't running constantly. Changing those fans is a big PITA!
Why? So the fan isn't running constantly. Changing those fans is a big PITA!
Running the fans at those very low speeds isn't going to significantly affect the fan lives versus how most run the fans during the summer/winter to affect cabin temps.
Here's the processor board for the CCU;
During development and early production, the processor used an external EPROM. Once the software was finalized, production used a masked ROM in the 80515.
The small 8 pin IC in the upper right is the external flash memory used to store the CCU's fault codes.
During development and early production, the processor used an external EPROM. Once the software was finalized, production used a masked ROM in the 80515.
The small 8 pin IC in the upper right is the external flash memory used to store the CCU's fault codes.
What part number is on that CCU? Is that a later 993 unit? I have (not just early production) 964 CCUs with socketed EPROMs. They are just a pain to remove, as you have to desolder some connections in order to split the two main boards.
Originally Posted by SpyerX
Why? So the fan isn't running constantly. Changing those fans is a big PITA!
They tend to last 100K+ miles and/or 15 years or more of solid running. Do you know anyone that's replaced them more than once?
05-19-2020, 02:20 AM
CCU upgrade - 993 flash?
