AC Yes, Heat No
Thread Starter
Racer
Joined: Sep 2010
Posts: 378
Likes: 21
From: DFW
AC Yes, Heat No
Team,
New to 993 and just picked my car up few weekends ago. AC works well (minus squeeling at lower fan speeds). Heat was working, but as of today does not. Symptoms:
-Intermittent working fan at higher speeds when heat is on only (it runs for a second, then shuts off, then may come on a few seconds later, etc)
-No heat at all...at no speed of the fan
-Fans seems to blow cold air at lower speed consistently
I look at bergvillfx and didn't seem to find anything similar to this. Thoughts?
New to 993 and just picked my car up few weekends ago. AC works well (minus squeeling at lower fan speeds). Heat was working, but as of today does not. Symptoms:
-Intermittent working fan at higher speeds when heat is on only (it runs for a second, then shuts off, then may come on a few seconds later, etc)
-No heat at all...at no speed of the fan
-Fans seems to blow cold air at lower speed consistently
I look at bergvillfx and didn't seem to find anything similar to this. Thoughts?
Burning Brakes
Joined: Feb 2018
Posts: 1,216
Likes: 239
From: Southwest
I recommend scanning the car for fault codes at the OBD port. I suspect you have a faulty flap servo motor somewhere which may be stuck halfway. The motors can be repaired for less than the cost to replace once you have identified which ones are playing up.
Last edited by Meenrod; Oct 29, 2019 at 09:11 PM.
RL Community Team
Rennlist Member
Rennlist Member
Joined: Jul 2004
Posts: 10,597
Likes: 2,049
From: Dallas, TX
Yes, if you have an OBDC reader such as Durametric you can read the HVAC codes.
The squealing fan may be drawing too much current and the CCU or whatever is controlling it is shutting it down as a result. You may be able to grease the fan's bushings with a little white lithium grease to free it up.
In any event Tore will know where you need to go with this.
Andy
The squealing fan may be drawing too much current and the CCU or whatever is controlling it is shutting it down as a result. You may be able to grease the fan's bushings with a little white lithium grease to free it up.
In any event Tore will know where you need to go with this.
Andy
Rennlist Member
Joined: Apr 2004
Posts: 2,569
Likes: 536
From: Oslo, Norway
Typical scenario of a failing rear fan.
First chapter of my DIY page here:
https://www.bergvillfx.com/index.php...on-system-test
Cheers,
Tore
First chapter of my DIY page here:
https://www.bergvillfx.com/index.php...on-system-test
Cheers,
Tore
Thread Starter
Racer
Joined: Sep 2010
Posts: 378
Likes: 21
From: DFW
Thanks all. Seems like after going through Tore's page, it' points to the notion of a heater blower motor. However, when you click his link, it shows a broken page from Vertex Auto. When I go through and search for this part from the main site, I assume this is the part that needs to be purchased?
https://www.vertexauto.com/porsche-9...ly-p-4836.aspx
Anyone else have knowledge and can confirm? Tore mentioned, "I would recommend to buy a complete motor with fan cage. JP Group has this available." This isn't quite clear either as JP Group I couldn't find after a web search.
Thank you all
https://www.vertexauto.com/porsche-9...ly-p-4836.aspx
Anyone else have knowledge and can confirm? Tore mentioned, "I would recommend to buy a complete motor with fan cage. JP Group has this available." This isn't quite clear either as JP Group I couldn't find after a web search.
Thank you all
Burning Brakes
Joined: Feb 2018
Posts: 1,216
Likes: 239
From: Southwest
That is the motor, sans cage. You may want to find one with a cage to make installation easier. Have you tried Pelican parts?
Before you do any of that- check to see that it is your fan motor that is faulty- have someone turn the fan on and off while to stand at the back and check to see if its turning / making noise/ blowing, etc. Always worth checking your fan blower fuse too just in case.
Before you do any of that- check to see that it is your fan motor that is faulty- have someone turn the fan on and off while to stand at the back and check to see if its turning / making noise/ blowing, etc. Always worth checking your fan blower fuse too just in case.
Thread Starter
Racer
Joined: Sep 2010
Posts: 378
Likes: 21
From: DFW
Update. Checked fuse and relay...wen through testing protocol from Tores site. Rear Aux fan simply blows intermittently when temperature is turned to heat.
I assume this this means I need to replace fan motor?
This brings me back fo previous question. Which part is needed? I speculate motor inside isn’t difficult to get to but has anyone done this?
I assume this this means I need to replace fan motor?
This brings me back fo previous question. Which part is needed? I speculate motor inside isn’t difficult to get to but has anyone done this?
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Rennlist Member
Joined: Apr 2004
Posts: 2,569
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From: Oslo, Norway
I guess your rear fan periodically runs on high (full) speed due to a failed low speed resistor. The CCU will default to high speed if it senses that the fan does not run on low speed when needed. The CCU will also shut down the two front main fans to signal this problem.
Does the fan run in two speeds when doing the described test?
Cheers,
Tore
Does the fan run in two speeds when doing the described test?
Cheers,
Tore
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Thread Starter
Racer
Joined: Sep 2010
Posts: 378
Likes: 21
From: DFW
I guess your rear fan periodically runs on high (full) speed due to a failed low speed resistor. The CCU will default to high speed if it senses that the fan does not run on low speed when needed. The CCU will also shut down the two front main fans to signal this problem.
Does the fan run in two speeds when doing the described test?
Cheers,
Tore
Does the fan run in two speeds when doing the described test?
Cheers,
Tore
and back fan runs intermittently at the same speed no matter what speed I choose on the ccu.
front fans run at same time as back fan and run intermittently.
Just noticed a new detail....when the fans kick on the air flow ceases through the vents. When the fans stop running, cold air blows.
Thread Starter
Racer
Joined: Sep 2010
Posts: 378
Likes: 21
From: DFW
https://www.vertexauto.com/porsche-9...ly-p-4836.aspx
But, there does appear to also be, left and right blower motors along with AC Evap Blower Motor. Just wasn't sure which "blower motor" was the right one. If it is the Blower motor, i can pull the part and likely just install that in the housing.
However, its seems like the diagnosis may be switching to a failed low speed resistor.
Thread Starter
Racer
Joined: Sep 2010
Posts: 378
Likes: 21
From: DFW
Haven’t heard back from anyone here. Assume this means folks are stumped and I should take to dealer?
specifically I have 2 different potential diagnoses from this group. Just wondering if my newly supplied data helps refine the recommendation.
Thanks to the great ideas and help so far!
specifically I have 2 different potential diagnoses from this group. Just wondering if my newly supplied data helps refine the recommendation.
Thanks to the great ideas and help so far!
Rennlist Member
Joined: Apr 2004
Posts: 2,569
Likes: 536
From: Oslo, Norway
I am not stumped at all, but you are not bringing any important information to this case. Your posts indicate that it might be an idea for you to let an auto electrician to look at this.
If your rear fan run intermittently on full speed only, you have a failed rear fan low speed circuit, most probably a failed low speed resistor. There might be problems with the HVAC servo motors as well, and all this can be diagnosed by following my DIY page mentioned above.
Cheers,
Tore
If your rear fan run intermittently on full speed only, you have a failed rear fan low speed circuit, most probably a failed low speed resistor. There might be problems with the HVAC servo motors as well, and all this can be diagnosed by following my DIY page mentioned above.
Cheers,
Tore
Banned
Joined: Nov 2002
Posts: 4,580
Likes: 229
From: London
Just in case you need a second opinion, If your rear fan run intermittently on full speed only, you have a failed rear fan low speed circuit, most probably a failed low speed resistor. There might be problems with the HVAC servo motors as well, and all this can be diagnosed by following Tores DIY page mentioned above. 
Thread Starter
Racer
Joined: Sep 2010
Posts: 378
Likes: 21
From: DFW
Just in case you need a second opinion, If your rear fan run intermittently on full speed only, you have a failed rear fan low speed circuit, most probably a failed low speed resistor. There might be problems with the HVAC servo motors as well, and all this can be diagnosed by following Tores DIY page mentioned above.
Tore - thanks! I will read through your site's DIY again. Since I didn't hear back from you or anyone after answering your questions (perhaps I didn't answer clearly), I assumed folks were stumped. I will start with replacing low speed resistors (both oil and HVAC as I understand replacing both at same time is best practice). Once I accomplish this, I will report back to the crew.
Thanks!