Engine Compartment Blower not working

[michael.williams1]

A few days ago I noticed the engine compartment blower had stopped working and, because the heat wasn't clearing when the car was stationary, it could develop a slight misfire. Can anyone help me by providing a link to a circuit diagram for the 987.2S or any advice on where to start looking so I can investigate this problem? I thought I'd start by disconnecting and testing the fan and if that's ok I'd try and find the temperature sensor. I assume there is also a relay located somewhere but my Driver's Manual provides no help on the location of this at all! Does anyone know where the sensor and relay are located? I did check the fuse in the driver's footwell yesterday and that is fine ...

 

[Motorhead]

Hi Michael,

For starters this link will give you an idea where to find the sensor for the engine compartment fan [R/H inlet manifold?]; not sure where the relay is located though.

https://www.boxa.net/topic/95610-engine-compartment-fan/

Jeff

Edit: I found this on Google, although probably it relates to a LHD car … but I’ve no idea which relay is #8!

 

[michael.williams1]

Hi Michael,

For starters this link will give you an idea where to find the sensor for the engine compartment fan [R/H inlet manifold?]; not sure where the relay is located though.

https://www.boxa.net/topic/95610-engine-compartment-fan/

Jeff

Edit: I found this on Google, although probably it relates to a LHD car … but I’ve no idea which relay is #8!

Thank you Motorhead. I've looked at this today and have so far located the Fan Relay and Fuse which are mounted on a bracket in the left hand wheel arch of the trunk, under the carpet which was fairly easy to pull out. The 10 Amp fuse has not blown and I removed the Relay and tested it and that is woking too, so I have eliminated those. I also checked the 7.5 Amp fuse in the driver's footwell which apparently (according to the little booklet in the fuse box) feeds the blower relay and that was OK too. I was expecting to find some direct wiring continuity between the relay and the bower motor but couldn't establish anything. I will check again tomorrow as that could be an issue(?).

Does anyone have a wiring diagram of this circuit?

The temperature sensor and blower motor could be faulty but I can't see a way to get some power onto the blower connection without removing the motor itself.

 

[michael.williams1]

In the absence of anyone coming forward with wiring diagrams - not just on here but on other forums too - (are they unobtainable?) I thought it would be useful to record what I've found so far. The blower relay has 5 pins:
1. Red Blue wire, 12V when ignition on
2. Yellow Red wire (which I think must connect to the DME as this measured about 4.5V) and is probably switched to ground to activate the relay when the temperature sensor resistance falls due to rising engine bay temperature
3. Red Black wire which powers the blower motor when the relay is activated
4. Not connected
5. Red Black wire. 12V hot, even with the ignition off

The temperature sensor has a resistance of around 2k2 ohms at ambient and falls to about 200 ohms as temperature rises to peak engine compartment levels. I removed this and tested it with a heat gun and multimeter. It seems to be working.

I've powered up the blower motor and that is working. I suspect the relay - whilst it tested ok - is probably not ok when it is under load. I've ordered both a relay and a temperature sensor, so hopefully one or both of these will fix the problem. Failing that I have an appointment at the car doctor!

 

[malarcy]

Are you sure it's "broken" ?- it doesn't trigger all the time - mine comes on sometimes when sat in traffic or at the end of a decent drive - I hear it perhaps once every half a dozen outings when I switch off, and infrequently in normal driving.

I found this information on the trigger conditions. https://www.boxa.net/topic/95610-engine-compartment-fan/#findComment-1329389

There could be other causes of a slight misfire, whilst of course it could be related I don't remember it being a cause discussed on the forums.

A diags unit with some Porsche specific features should be able to tell you live readings from temp sensors and also any internal codes thrown - in this case it would be able to tell you what the engine compartment temp sensor reading is as the car sees it. The Foxwell NT530 also has the capability to trigger some functions - I don't know for sure but it may be able to "run the engine fan" on demand to prove the basic operation of the various components.

 

[AndrewT]

Are you sure it's "broken" ?- it doesn't trigger all the time - mine comes on sometimes when sat in traffic or at the end of a decent drive - I hear it perhaps once every half a dozen outings when I switch off, and infrequently in normal driving.

My 987.2 Cayman S used to behave this way too.

 

[michael.williams1]

Are you sure it's "broken" ?- it doesn't trigger all the time - mine comes on sometimes when sat in traffic or at the end of a decent drive - I hear it perhaps once every half a dozen outings when I switch off, and infrequently in normal driving.

I found this information on the trigger conditions. https://www.boxa.net/topic/95610-engine-compartment-fan/#findComment-1329389

There could be other causes of a slight misfire, whilst of course it could be related I don't remember it being a cause discussed on the forums.

A diags unit with some Porsche specific features should be able to tell you live readings from temp sensors and also any internal codes thrown - in this case it would be able to tell you what the engine compartment temp sensor reading is as the car sees it. The Foxwell NT530 also has the capability to trigger some functions - I don't know for sure but it may be able to "run the engine fan" on demand to prove the basic operation of the various components.

Thanks. Yes, I'm absolutely certain it's not working at all. It's stopped working. When I first got the car 3 months ago it would come on in a traffic queue or at the end of drive. It's not doing that now, it's not coming on at all. We had some very high ambient temperatures of nearly 40 degrees C on a recent holiday so I reckon the fan was probably running constantly at certain times, and perhaps that's degraded the relay. Anyway, replacement components and an iCarsoft Por V2 have been ordered.

 

[michael.williams1]

Yesterday, the parts arrived and I replaced both the temperature sensor and the relay. The fan started working again when the engine compartment was up to temperature. However, today it is not working and I had a misfire as a result! I suppose this narrows it down to an intermittent fan or an issue with the DME not triggering the relay. As the car is under warranty, this is where I give up! It's now booked into Porsche Centre Bournemouth for them to have a look at next Thursday ... I'll let you know what the outcome is.

 

[malarcy]

Yesterday, the parts arrived and I replaced both the temperature sensor and the relay. The fan started working again when the engine compartment was up to temperature. However, today it is not working and I had a misfire as a result! I suppose this narrows it down to an intermittent fan or an issue with the DME not triggering the relay. As the car is under warranty, this is where I give up! It's now booked into Porsche Centre Bournemouth for them to have a look at next Thursday ... I'll let you know what the outcome is.

Interested to hear the result - thanks for keeping the thread updated.

 

[Motorhead]

Ditto Michael.

I assume that the iCarsoft hasn’t given you any clues? Best to leave it to the dealer to sort it out if you have a warranty. They can plug-in the PIWIS diagnostics which hopefully will give a more in-depth analysis of your issue.

Jeff

 

[michael.williams1]

Unfortunately the iCarsoft turned out to be a faulty unit that I’ve returned for replacement, so I was unable to run codes! At this point, having paid for a warranty, the OPC can take a look at it. They have all the gear and the skills … I’ll let you know what they find. It may help someone else in the future.

 

[michael.williams1]

Update: Yesterday, as mentioned above, I set out to drive the car to OPC Bournemouth, with engine cover removed and windows open to try and promote plenty of engine compartment cooling. First 20 miles, no problem, then half way through the New Forest it developed quite a nasty misfire + CEL. The AA came out and diagnosed a misfire on cylinder 4 and arranged for a flat bed Recovery vehicle to take me the remaining 12 miles. After a number of revised ETAs this eventually showed up after 3.5 hours! Anyway the car is now in OPC Bournemouth for diagnosis and repair. I'm wondering if ignition coil 4 has started to break down due to engine compartment temperatures or if this is just another end of life part? I can't find any evidence of the ignition coils having ever been replaced so I assume they are original. Maybe it's time to change the lot(?). I'll see what Bournemouth advise ...

 

[malarcy]

if you have warranty then coil packs are covered - but they will only swap ones that are cracked - I know someone who had a claim and 5 out of 6 were showing cracks - but they wouldn't cover the 6th - he paid to get that one done as well.

 

[ianthow]

No 4 coil is towards the front nearside of the engine, close to the bulkhead and away from the engine bay cooling fan. This location probably sees least cooling air flow. This coil failed on my 987.2 about 6 years ago and I replaced all 3 on that side (bank2). No failures on bank one, now 16 years old and with 100K on the clock. The two coils that were still working were put aside as emergency spares.

 

[michael.williams1]

Bournemouth have advised that all 6 coils should be changed. I think that's the right thing to do. They are all as old as the car (2011) and now one has gone the others probably won't be far behind. One of my AC condensers is leaking and the exhaust flange bolts are badly corroded, so I think I'll get the lot done whilst it's in there. They tested the engine purge fan and found that to be working fine at both Stage 1 & 2, so it looks like the misfire was only caused by the failing coil. The AA man who attended my call out said that Cayman's are notorious for it ... I didn't know that but I do now!