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Bromers
Newbie


Joined: 09 Dec 2012
Posts: 14



PostPosted: Sun Sep 23, 2018 8:39 pm    Post subject: No Heat Reply with quote

Heater will not give out any heat even though everything appears to be working as normal. Tried it with AC on and off, a range of temp settings including hi and different fan speeds but no joy. Looking at fuse descriptions other things would not be working as well if it was just a blown fuse. No longer under warranty therefore does anyone know what it is likely to be?
Mrs B thinks this is the worst thing that could failed on a car, so I am under significant pressure to fix it ASAP. Confused
 
  
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deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6987
Location: Brighton


PostPosted: Mon Sep 24, 2018 5:57 pm    Post subject: Reply with quote

These do suffer from heater fans packing up but i take it the fan is running but no hot air is coming out ?

Im afraid it needs a tester on it and a fault code read out of the A/C system .. it will be a failed sensor or an over reading one i expect ..

Things like this are really a garage job im afraid unless you have a tester and can check a few more things for me .
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Bromers
Newbie


Joined: 09 Dec 2012
Posts: 14



PostPosted: Tue Sep 25, 2018 8:47 pm    Post subject: Reply with quote

Thanks for the reply deMort and the offer of help! Had another good look and this time everything started working normally including in mono and dual AC modes. All I can think of is that everything cooling down has reset something or the servo motor to allow hot air from the heater matrix may have been stuck. Hopefully it will not happen again. Will a normal OBD2 fault code reader get the codes out of the AC or does that require something more specialised?
 
  
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Sulz
Silverstone


Joined: 13 Feb 2015
Posts: 133



PostPosted: Tue Sep 25, 2018 8:59 pm    Post subject: Reply with quote

I had this exact issue on mine had and had it fixed under warranty. Issue with the solenoids/ change over valves.

I had an issue with the sports exhaust too as they use the same solenoids.

Annoyingly Porsche know their was an issue with them as they have changed the ones they used but didn’t do a recall to change the older ones.

More details below.
https://rennlist.com/forums/991/800240-ongoing-change-over-valve-issues-on-991-a.html

If you google “991 change over valve” loads of threads come up and “991 solenoids heating issue”
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958 Cayenne
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deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6987
Location: Brighton


PostPosted: Wed Sep 26, 2018 6:08 pm    Post subject: Reply with quote

I know the issue and the recall well .. i can actually say we did the recall and then there was a recall again on the parts we had fitted as they changed the design of the valves yet again !

Although one of them did give a coolant message on the dash due to a thermostate valve failure none of the valves have much to do with the heater blowing cold air ..

Well as far as im aware anyways .... i never really checked it ..

In fact the only message was about coolant / thermostate when in fact 8 valves had actually stopped working .. car cant monitor them .. 8 things inop and 1 message Sad

Basically though you will get a coolant failure message if its the valves displayed on the dash.

Im not sure what tester you have or if it will be able to go into the A/C system .. try it though .. if you can find A/C on the list of modules have a look .. if you can get at fault codes for that system it would help.

Intermitant fault .. hmm .. strikes me it is temp related so more likely to be a sticking flap motor perhaps .

Im guessing though .. always a bad idea Very Happy

Monitor it and see how it goes and let me know if you can get a code.
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blackram
Trainee


Joined: 11 Jul 2017
Posts: 77
Location: Bristol


PostPosted: Mon Oct 01, 2018 3:45 pm    Post subject: Reply with quote

As already mentioned it is probably a faulty changeover valve which may have over-heated and has started to fail. Covered under warranty and are replaced with latest version. Just had one done (worryingly it had started to melt!) and all ok so far.
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blackram
Trainee


Joined: 11 Jul 2017
Posts: 77
Location: Bristol


PostPosted: Mon Oct 01, 2018 3:59 pm    Post subject: Reply with quote

As already mentioned it is probably a faulty changeover valve which may have over-heated and has started to fail. Covered under warranty and are replaced with latest version. Just had one done (worryingly it had started to melt!) and all ok so far.
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Bromers
Newbie


Joined: 09 Dec 2012
Posts: 14



PostPosted: Wed Dec 26, 2018 5:47 pm    Post subject: Reply with quote

It was the changeover valve, now all sorted by OPC. Switching the fan on and off would get it working again but it could take up to 20 goes and every time you take the key out same issue. There were never any warning messages so hopefully this may help the next person who is effected by these quality items!
 
  
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