PCCM Plus A/C Blows Warm When Powered On

I dove into the PCCM Plus pool with an installation today on my 03' w/MOST, and BOSE, CDR23 and no CD changer. I had Rod's crew at Car Audio Innovations do the install and it came out great. He routed microphone to OEM location and even did the custom batwing modification as done by a different installer posted here a few months ago. I was a bit anxious as I was hoping not to experience the 'car under motion' error...and was relieved that's not an issue. The PCCM Plus functions as expected....radio....Nav (installed SD card) and SiriusXM (preview channel only - haven't activated.). This is the good news....the bad news...when PCCM Plus is powered up the A/C blows warm within a couple of minutes. It doesn't matter what temperature I have it on...fan works....if I drop to 'lo' fan goes to max as you'd expect but the temperature blows very warm. When it's powered off....after a few minutes it goes back to operating normally (ice cold). I brought it back to CAI and they checked the connection to the climate control unit...all solidly set. It was late so I took the car home and thought I'd reach out to the community for thoughts. What's the most likely issue....defective MOST control unit included with PCCM Plus? CAN Bus issue? I think I read somewhere that the Comfort CAN controller in 996 is incorporated in the instrument cluster and communicates between the cluster, radio and air conditioning. They did remove the instrument pod to gain access to route the microphone cable....could something have happened? This is so odd....hoping it's something simple. I appreciate any thoughts. Kevin

This is very interesting. My car has PCCM plus installed. The setup is Bose/Navigation/MOST with no accessories, like the CD changer. The OEM radio is PCM 2.0. It is similar to your set up. I have got the micro SD for the navigation, too. The important part is MOST. This is the problem with the A/C in my car. PCCM plus controls the brightness of the A/C control panel screen. When the PCCM plus display goes dim, the A/C control panel display goes dim together at the same amount (or brighter). It is the same for automatic brightness and the manual brightness. (With the OEM radio, it is synced with the three digital displays in the instrument cluster.) The brightness in the day time with either automatic or manual is OK. The brightness in the night time is not dim enough with automatic. It is marginally better with manual. With the OEM radio, the brightness of both screens works very good (bright enough and dim enough) in all conditions, day, night, manual, and automatic. Most of the time, the radio was not used and not turned on when I had the OEM radio. In the night time, the brightness of the A/C control panel became dim enough when the headlight was turned on (along with the three digital displays in the instrument cluster). So, my thinking was that with PCCM plus turned off and the headlight turned on, the A/C control panel display should go as dim as the OEM radio. It is not the case at all. In fact, the brightness goes to the brightest and gets stuck there. The brightness of the A/C control display works (marginally in a different way) only when PCCM plus is turned on. Luckily, the A/C (temperature control) works in my car. But, there are other problems. When the scan was made with PIWIS for any fault, the A/C unit and the instrument cluster were not communicating properly. I don’t know if it was coincident. Having said that, the onboard computer gets reset randomly. For example, the trip distance counter becomes “zero” randomly. The onboard computer is useless now. May I continue? There are few more. The GPS and RBDS clock sync do not work. The navigation information is randomly displayed on the onboard computer without any active route in PCCM plus. The unit itself reboots randomly. I am not sure if this is a problem, but PCCM plus cannot be turned off independently. It means that PCCM plus always turns on automatically when the ignition is turned on. The OEM radio dose not do it. I believe all of the problems (other than rebooting) are related to the installation with MOST. The OEM radio is integrated into the car. It looks like PCCM plus is trying but not exactly being integrated properly. I have been dealing with the problems since last fall. There are no solutions from the dealer or Porsche Cars North America so far. Do you have any other problems, other than the A/C? *****EDIT***** I went back to the OEM radio once to see what happened. All of the problems went away. After PCCM plus was installed again, all of the problems came back with it.

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Very similar with exception of PCM 2.0. What year is your car? I just checked and when the headlights are on none of the buttons on the PCCM Plus are lighting up. I went into settings and confirmed set to Amber. I also tried white with no change. In terms of the brightness of the A/C control panel....there is no change in brightness whether headlights are on or off or whether the PCCM Plus is switched on or off. I checked manual setting of instrument panel display and it was set to full brightness. If I manually dimmed it did not change brightness of the A/C control unit or do anything to illuminate the PCCM Plus buttons. When I checked brightness setting in instrument panel is was set to brightest setting. As note above, no change in A/C control panel whether or not I turned lights on/off. Did you have the scan done at the dealer? No PCM 2.0 in my car so haven't experienced those onboard computer / instrument panel display related issues. The PCCM Plus in my car doesn't turn on automatically as I changed a PCCM Plus setting. I was thinking from other posts that MOST installs were going better than earlier Analog cars. I can't recall if there were running changes with MOST between 03' - 05' (end of 996). If so, I wonder if this is a factor?

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Thanks for more info. Mine is 2004. There seems to be some glitch with the illuminations, too, besides the temperature problem. Probably, I was not clear enough. During the night time, first, the headlight is turned on with PCCM plus turned on already. Then, PCCM plus is turned off. The illumination for the A/C panel goes full bright and gets stuck. Also, when the headlight is turned on without PCCM plus turned on, it is stuck at the full bright. Obviously, this needs to be done with the brightness turned down manually by the **** at the upper left side of tachometer. Also, it needs to be done in the dark. There is light sensor. All of the three digital displays go dim in my car. The one for A/C panel does not. Yes. PCM 2.0 was re-installed to check if all of those problems were only associated with PCCM plus, and it was the case. Before switching back from PCM 2.0 to PCCM plus (hoping to get those problems repaired), the scan was made. The faults for the instrument cluster and the A/C unit only have come up after the installation of PCCM plus. The first item on the page 25 of the manual is the way PCCM plus turns on/off. From that, I was expecting PCCM plus not to turn on automatically. I cannot find the setting for the automatic turn on/off. Perhaps, the closest one is the standby time on page 31. It does not change the behavior for the automatic turn on with mine. I have checked several threads about the installations of PCCM/PCCM plus. So, I am aware of the difference between analog and digital installations. I think we are dealing with two different problems. It appears that the installation with MOST is more of plug and play (less problems) than analog. We are now dealing with the problems after the successful installation. There is some chance that the installation is causing the problems, like faulty connectors and wires. But, it sounds like not the case. I only can guess because the dealers (more than one) and Porsche Cars North America do not have any information. My best guess from the information gathered so far is that PCCM plus is not integrated into the car properly for the installation with MOST. The configurations for CAN and the instrument clusters probably need to be changed to accommodate PCCM plus. The software/firmware of PCCM plus probably needs to be updated to accommodate MOST. With analog installation, there should not be any problems once the installation is complete successfully (maybe with the exception of the one with navigation without MOST originally). In such case, PCCM plus is less integrated to the car. I think CAI has more information and better insight about MOST. I am curious to know what they think.

I am having the same problem in my 2004 911 4s. When PCCM is turned on air blows warm. When turn off air goes back to normal in a minute. Seems like I can hear something kicking in when I turn the pccm off (maybe air condition compressor). I don't know. But this is a terrible problem and I hope someone has an answer. Thanks

The A/C issue is crazy isn’t it?! How long have you had PCCM installed before it started acting up? Also, do you have MOST, Bose, CDR23…PCM2.0, cd changer, etc. No surprise, Porsche NA is not helping in any way. I don’t really want to take mine to the dealer. The issues I have are as follows: A/C blows warm when powered on and operates correctly when off. The PCCM buttons don’t light up when headlights are on. Light sensor on PCCM doesn’t function. The rest of the unit functions as expected. I have no way of knowing for sure but I wonder if issues with MOST installations have to do with the PCCM included MOST Control Unit? I’m very disappointed that this Porsche approved product is proving to be a $1300+ headache for so many.

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I did not mentioned MOST control unit previously. But, it is the part of CAN-bus and MOST. So, the software/firmware update is needed for the problem within the unit, like no light for the button, etc. The re-configuration is needed for CAN-bus and MOST, perhaps, as simple as re-designed, new MOST control unit. ...and there is no indication of definite ending to the story.

I am taking mine to Porsche dealer to see if they can help with the air conditioner issue.

I think I'm in the same boat in needing to go to the dealer. Man, the install done by Rod and his crew at CAI is so sweet. The custom blend of the multimedia box into the batwing turned out great. I really hate to have dealers put their hands on it and do something to it in the process or point to having the PCCM Plus installed by third party as culprit...which would be pure rubbish. Please keep us posted on what you find out and I'll do the same. Thx. Kevin

Here is what happens to mine. I can't believe someone does not have an answer to this. Air is fine when pccm is off. When turn on radiator fan stops and air goes warm. Also RPS's go down and car seems to run rough. Probably because RPM's dropped too low. When turn pccm off, fan comes back on, there is a click sound like a compressor coming on and rpm's go back to normal. Surly someone out there has the expertise to tell us what is happening and how to fix. I am taking to dealer but fear they will not be able to fix either. Have you posted your issue to Porsche boards, places that specialize in working on them, etc.

I'm happy to share that Rod & Jake at CAI came through for me! As a reminder, I have an 03' (MOST, Bose, CDR23 & no CD changer) and after installation I was experiencing three issues in order of importance: 1. A/C compressor would trip when PCCM Plus was powered on 2. Radio buttons would not illuminate 3. Radio would not power on / off with key #1 was addressed when they realized the yellow square plug that was plugged into CDR23 (and had a spot to plug in on PCCM Plus) needed to be left disconnected. From what I was told, the yellow plug is an analog 12 volt turn on for the earlier cars, 97-02, both Bose and HiFi (black with red wire on the car side), data on the MOST cars 03-05, and analog low level signal (4 conductors) and ground for the 97-02 cars with HiFi package. In case of Bose, it takes high level/speaker level signal in from a separate brown speaker wire plug in radio cavity. The theory that the awesome guys at CAI think is the PCCM Plus doesn't know which car it's in, and may be throwing 12 volts into a data wire on the MOST Bus cars. The Porsche Technical Bulletin (which I gave to the guys) should likely say to not plug in the yellow square amp plug on the MOST bus cars! Once they unplugged the yellow plug the A/C compressor stopped kicking off when it was powered up. Fred - I'm thinking you need to have your installers make sure the yellow square plug is removed from the PCCM Plus. #2 & 3 Resolved with tapping into switched accessory / illumination power. Now the radio powers up / down with key (can manually turn off as well) and the radio lights are illuminated when headlights are switched on. I can't say enough how appreciative I am of Rod & Jake in troubleshooting and resolving my issues. I hope this post is of value to others in the future who may have similar problems.

Are there any firmware updates or additional info from Porsche regarding the AC and illumination issues? Thanks.

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Sorry to say Porsche hasn�t released any new software updates.

Doesn't look like you need anything except to follow the instructions in this post and all will be good.

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Apologies for reviving this thread - i found it via a Google search as I had exactly the same symptoms. My solution is a little easier: make sure the setting in the "hidden menu" of the PCCM+ unit is set to "CAN" and not to "AMP". This solved all issues for me - A/C is working fine, PCCM buttons are illuminated and it switches on/off with the key My car is a 2003 Turbo with MOST and cd changer (originally had a CDR-23 as well)

“Apologies for reviving this thread - i found it via a Google search as I had exactly the same symptoms. My solution is a little easier: make sure the setting in the "hidden menu" of the PCCM+ unit is set to "CAN" and not to "AMP". This solved all issues for me - A/C is working fine, PCCM buttons are illuminated and it switches on/off with the key My car is a 2003 Turbo with MOST and cd changer (originally had a CDR-23 as well)” That right there is priceless and why the internet community is awesome. Thank you, thank you, thank you -John