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Blinking HVAC Lights

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Old 03-18-2017, 05:24 PM   #1
cky3k
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Default Blinking HVAC Lights

I have an 02 Boxster S with 95k miles on it. The HVAC lights have started blinking. The shop I am at said it was the alternator. We replaced it. It wasnt. They then found a code being thrown from a bad fan (996 573 915 00). We replaced it. It wasn't that either. The fairly reputable Porsche specialty shop doesn't have any idea what this blinking means. They are now looking further, and guessing it may need a new HVAC unit. They do not have one available to swap out for a test.

Had anyone had any experience with the HVAC lights blinking? They blink 10 times as soon as I start the car, and then stop. Everything appears to be functioning fine.
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Old 03-18-2017, 05:58 PM   #2
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I have an 02 Boxster S with 95k miles on it. The HVAC lights have started blinking. The shop I am at said it was the alternator. We replaced it. It wasnt. They then found a code being thrown from a bad fan (996 573 915 00). We replaced it. It wasn't that either. The fairly reputable Porsche specialty shop doesn't have any idea what this blinking means. They are now looking further, and guessing it may need a new HVAC unit. They do not have one available to swap out for a test.

Had anyone had any experience with the HVAC lights blinking? They blink 10 times as soon as I start the car, and then stop. Everything appears to be functioning fine.
My references indicate this indicates a problem with the A/C system.

Has the shop queried the HVAC control unit for error codes? I mean besides the time it found a bad fan error code.

This requires a Porsche diagnostics computer (PST2 or PIWIS (or a *good* copy)). Durametric might be able to work too.

Something else to consider is just clearing the fault codes. Fault codes can sometimes get set from a low battery or even a battery disconnect or disconnecting the HVAC controller.

Less likely it can mean the HVAC needs to be "adapted" the car. The Porsche diagnostic computer can do this. Why I guess an otherwise perfectly good working system would require this again is beyond me. But if you tell me you recently went through a bad battery with this car maybe something got "goofed up" from a low or dead battery.

In either case you are going to need a shop that has the right diagnostic computer and the knowledge to make the most of it.
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Old 03-19-2017, 03:24 PM   #3
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Thanks so much for the reply, Macster. I have a few follow up questions.

Can you tell me more about what you think this indicates with the A/C system?

I'm not sure what system the shop has used to check for error codes. But I can tell you they missed a code relative to the hvac earlier in the week for a separate issue (fan clicking inside the dash- they said there was no code. Once the hvac started blinking though, they determined the code was only registering when they hit a specific button- i think the recirculate button). None the less, they are telling me there are no other codes at this time. Is there a system that detects codes better than others? I'm a little disappointed that I was told there was no code for the fan making noise, only to find they were able to find it later by pushing different hvac buttons while looking.

When you say: "Something else to consider is just clearing the fault codes. Fault codes can sometimes get set from a low battery or even a battery disconnect or disconnecting the HVAC controller," did you only mean this if there is actually fault codes that we are aware of? Just to be clear, I am told there are no codes. (although it seems definitions of this may vary) I can tell you the battery was disconnected prior to this blinking issue arriving.
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Old 03-19-2017, 06:49 PM   #4
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Thanks so much for the reply, Macster. I have a few follow up questions.

Can you tell me more about what you think this indicates with the A/C system?

I'm not sure what system the shop has used to check for error codes. But I can tell you they missed a code relative to the hvac earlier in the week for a separate issue (fan clicking inside the dash- they said there was no code. Once the hvac started blinking though, they determined the code was only registering when they hit a specific button- i think the recirculate button). None the less, they are telling me there are no other codes at this time. Is there a system that detects codes better than others? I'm a little disappointed that I was told there was no code for the fan making noise, only to find they were able to find it later by pushing different hvac buttons while looking.

When you say: "Something else to consider is just clearing the fault codes. Fault codes can sometimes get set from a low battery or even a battery disconnect or disconnecting the HVAC controller," did you only mean this if there is actually fault codes that we are aware of? Just to be clear, I am told there are no codes. (although it seems definitions of this may vary) I can tell you the battery was disconnected prior to this blinking issue arriving.
My Boxster references are boxed and I have no room to unbox them and store then on book shelves. (They consist of 64lbs of 3-ring binders some inches thick filled with manual pages.)

So I did a google search of a blinking HVAC turned up some posts that this indicates either the system is new and needs to be adapted or is faulty.

Then it occurred to me my Turbo references are accessible (these are in digital format) and I referred to my Turbo reference and in the A/C section (both my Boxster and my Turbo have the same HVAC system and I believe the Turbo reference applies to the Boxster HVAC system) and it specifically states that blinking HVAC display indicates a problem. The number of blinks may mean something specific but I have no info on this.

Regarding following the installation of a new A/C system regulator for instance: The display flashes after the ignition is turned on. In this case the system test must be carried out first. The A/C system regulator hereby leans the upper limit stops of the drive motor and the entire system is checked simultaneously!

As for erasing fault memory, here is some more info with some stuff omitted to avoid too much typing. After trouble-shooting or repairs erase the fault memory with the PST2 and carry out a test drive. After the test drive read out the fault memory with the PST2 again.

Fault code setting conditions: Fault codes can be set in serveral circumstances, e.g.: battery disconnect, plug connection disconnected, power failure, etc. In these circumstances no fault is present in the system and the fault memory must be erased.

For the PST2 it goes on: In order to be able to assess the fault exactly, the fault memory info key (F8) must be pressed. This information should be saved using the Save key (F4) and printed out. If a fault code is stored with 'not present' status and no other problems are present, then the fault memory must be erased.

After completing repair work, read out fault memory, press the info key (F8), switch off the ignition and switch on again. After a short period, the fault memory text goes from 'present' to 'not present', if the fault has actually been remedied.

I should point out my experience, what little I have as an owner of two Porsches with the HVAC system, is with the auto climate version of the HVAC. Both of my cars have this system. This system may be a bit more elelctronically sophisticated than the regular HVAC system (with which I have no experience).

The shop you select to use for this should have the proper equipment and know how to use it to diagnose the problem regardless of which HVAC system you have in your car.

Based on what you have posted I do not think this is the case.
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Old 03-21-2017, 07:59 PM   #5
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Thanks Macster! The shop called and said they are going to put in a new hvac unit. Hopefully that is all it is... It does sound like they are guessing, however.
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Old 03-27-2017, 10:43 PM   #6
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I have the car back. Installing a new HVAC display seems to have made the blinking go away. However, the LCD panel (where you would read the ofF letters) seems a bit dim. This may be my imagination, but it seems dimmer than I recalled. When I turn the lights on and off it does not get brighter and darker.

I do see that the buttons light up and then turn off when I turn my lights on and off, which leads me to believe this may be correct. My thinking is that if the LCD is supposed to get brighter and darker, since my lcd seems dim, maybe its stuck in dark (headlight off) mode.

Can anyone confirm if the LDC part of the hvac display is supposed to get brighter and daker when you turn the lights on and off?
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Old 03-29-2017, 10:05 PM   #7
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Old 03-30-2017, 12:12 AM   #8
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Originally Posted by cky3k View Post
I have the car back. Installing a new HVAC display seems to have made the blinking go away. However, the LCD panel (where you would read the ofF letters) seems a bit dim. This may be my imagination, but it seems dimmer than I recalled. When I turn the lights on and off it does not get brighter and darker.

I do see that the buttons light up and then turn off when I turn my lights on and off, which leads me to believe this may be correct. My thinking is that if the LCD is supposed to get brighter and darker, since my lcd seems dim, maybe its stuck in dark (headlight off) mode.

Can anyone confirm if the LDC part of the hvac display is supposed to get brighter and daker when you turn the lights on and off?
What I have observed is with the dash light brightness set to its dimmest setting when the headlights are turned off the A/C LCD brightens. When the headlights are turned on the A/C LCD dims.
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