I don't know if this is accurate or not. I can only relate what I experienced (or thought I did) and what the shop told me.
At age 62, I bought my 2006 Cayman S 987c in August, 2019. First Porsche, first real sports car. I loved it then and I love it now. After one week, the Porsche Communications Management/Radio (PCM. The head unit that controls nav, stereo, phone, etc) failed hard. Dealer quoted me $4,850 to replace with a 6 month lead time. I didn't like the sound anyway (Bose) so in Sep 2019 I had the best car stereo shop in town (population 350,000) install a Kenwood DPX503BT head unit and a pair of Alpine KTA-30MW amps, retaining the Bose speakers. I did not opt to buy the $750 wiring harness which would have allowed connectivity to the control switches in the steering wheel. I had a lot of issues with what I consider to be alternator electrical noise in the sound system. The shop installed filters and deinstalled/reinstalled the entire system at no charge at least once. It's still not resolved to this day. So I went into the winter of 2019/2020 like this, noticing that some times the heater would not work. Then it would. Then it wouldn't. I have a local shop that specializes in Mercedes/Jag/Rover and also works on Audi and Acura (I knew them from them working on my Acura TSX previously). They have the equipment to service Porsche so they asked me to bring the Cayman in when it was not heating. Since March of 2020, I tried several times. For whatever reason, it would start heating before I got to the shop. Since November 2020, I resumed trying. The last two times, I made it to the shop, freezing cold. They asked me to leave it running outside the bay door and the Audi/Porsche tech would come out with his laptop and connect in order to see the error codes it might produce. So I pulled up and stopped, called in (COVID protocol), they said he'd be right out. I suddenly did not feel comfortable leaving the car (Tiptronic) running and occupied so I set the emergency brake. Immediately I heard a pleasant clunk and the heat came on. Ruined the opportunity, they can't diagnose unless it's in an error state. The next time I made it there, I made my call, they said they'd be right out with the laptop. I took my foot off of the foot brake and heard the clunk, heater on. Today, I pulled up, called in, got out of the car and left the driver door cracked open. It was blowing cold. They took it inside and ran it for quite a long time, blowing cold. No error codes. The tech decided to check the heater module(s) (?) and opened the frunk. Clunk, heater on. Puzzled, he called his old friend who is the gray beard tech at the local Porsche dealership. Old Beard said he knew what it was: Aftermarket car stereo is interfering with the transmitted calls for action in the CAN (controller area network). Apparently even in a 2006 model the computer system in these cars is quite complicated (which is how all these error codes and all the other data get measured and recorded). He says the heater is calling for an on status but is not being heard because of the Kenwood unit. When another action takes place (Ebrake set, foot off of foot brake, frunk opened, etc) the heater call is somehow no longer suppressed and is answered. I don't know of anything else that is suppressed, everything else seems to always work fine. There is no combination of actions that will reliably allow the heater to come on. My shop guy told me that the car stereo installer did not do anything wrong or did not do a clean installation, it's inherent with the aftermarket head unit (the Kenwood in this case). He said he could not help me. The gray beard Porsche guy said he has seen this many times but has never worked it to resolution because it's not a Porsche problem. I'm an accountant, this is not my area of expertise and it seems wild and improbable but somehow likely and plausible at the same time. If any of you have any comments or similar experience, I'd really appreciate the feedback.
I know this may not help you, but I personally installed an Android head unit and MOST adapter in a 2007 CS, retaining the Bose amp and speakers. No alternator noise, no problems with the CAN coding or HVAC system.
I removed the CD changer as well and put a fiber optic loop in its place.
I don't have any other recommendations for you. It sounds like your stereo place added the "P" tax to your install.
Danny, it was hard to follow your reply (had to google "Android head unit" and "MOST") but I thank you for the clarity you provided. Thought about it a while and I now see clearly that my problem originates with the cheap piece of crap $159 Kenwood head unit. I'll work on it from there. Seriously, thank you for the insight.
I don't know the quality of Kenwood (although I had a Kenwood that made me happy in my boat) but they are a large company, they have probably heard of problems like this before, might they help?
Thanks for responding. I have another car audio shop who might be interested in taking on this challenge, we're exchanging emails (no way do I want to try to describe this over the phone). The Kenwood head unit is ok but I think I want an upgrade anyway. I swear when I play a song ripped to my iPhone through the car system it sounds better than the same song played from the source CD through the Kenwood CD player. But I may be crazy.
There is so much more to this story I left out due to TLDR which apparently it is anyway. The original installer is around age 30. Smart guy. Listened to me but didn't HEAR me. I said "You know, I like the tone controls flat. I don't want a lot of rapper bass. You know, driving down the street and the neighborhood can only hear the subwoofer going "ba BOOM ba buh, ba BOOM ba buh". I don't want an overwhelming bass like that." He nodded and said ok. When the install was done and he first let me hear it play, there was like no bass. I mean none. Like listening to an iPhone play through its speakers and I'm only exaggerating a little. WTF.
