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Join Date: May 2007
Location: Central Jersey
Posts: 104
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A/C 3 Speed Switch Problem?
Hey gang, I searched and couldn't come up with anything.
On my '85, the A/C blower intermittently changes speeds on it's own. Kind of creepy. The low speed works fine, the high speed works fine. The problem is with the middle speed. Occasionally (no pattern to speak of) when set to the middle speed, it will kick up to the high speed for a few seconds then back down to the middle then repeats. This seems to only happen when driving, not while idling. Anyone experienced this? If it's just the switch, that's simple enough, but I don't want to go to the expense/trouble if it may be something else. I thought I'd ask first. Thanks for your help!
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'87 930 - 100% stock '89 951 - 100% track '08 Audi RS4 - daily '85 911 Targa - sold |
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09-14-2007, 07:11 AM
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Todd, I had such a problem once on my 84' Carrera, and it turned out the switch was shorting out internally. It is tricky to replace without damaging the console, as it is glued in at the factory(again, it was a long while ago, and I did the repair in a parking lot far from home in Charlotte, NC with pliers and a screwdriver.) That switch carries a heavy electrical load.
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09-14-2007, 04:03 PM
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I would love to hear some more input on this. I believe this is what is going on with my car. My speed three will only work occasionally.
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Tom Hutchinson 80 Targa / 81 Coupe / 71 Targa (in Porsche heaven) My Garage Build: https://youtu.be/H0n_NwEQVbs "If one does not fail at times, then one has not challenged himself." Ferdinand Porsche |
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09-14-2007, 06:41 PM
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Make Bruins Great Again
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There was an article in Excellence about replacing the fan switch with an infinitely variable speed switch. IIRC it had decent instructions on how to remove the old switch.
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-------------------------------------- Joe See Porsche run. Run, Porsche, Run: `87 911 Carrera |
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09-14-2007, 07:58 PM
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I saw that. I sure don't like the price of that infinite switch.
I'll have to dig it out to see the step by step on pulling the switches. Thanks for the reminder.
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Tom Hutchinson 80 Targa / 81 Coupe / 71 Targa (in Porsche heaven) My Garage Build: https://youtu.be/H0n_NwEQVbs "If one does not fail at times, then one has not challenged himself." Ferdinand Porsche |
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09-14-2007, 08:26 PM
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Join Date: Dec 1999
Location: Richmond, VA USA
Posts: 1,058
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Look for a previous thread on this subject, titled "Carrera A/C fan switch -- an idea". If discusses an alternative to the expensive switch available from Griffiths.
Brian |
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09-15-2007, 03:33 PM
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Quote:
I think you'll find the article in the 11/05 issue. Let us know what to look for/look out for when you do the replacement.
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-------------------------------------- Joe See Porsche run. Run, Porsche, Run: `87 911 Carrera |
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09-15-2007, 04:52 PM
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Location: Chicago, IL
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Tod,
Last summer, I installed a new evaporator fan motor because the old one was sqealing, indicating the shaft bearings were shot. When I got the new fan installed, the speeds changed just like you're describing. A few guys replied to my inquiries, explaining that the new fan motor exposes the next weakest link. The general opinion was that it was the resistor pack that is directly under the passenger floorboard. Basically, this is a 3-speed rehostat. A guy who stripped out his air condtioning for a track car sent me his for cheap. That did it....worked like a charm. There are probably plenty resistor packs available for cheap and it was only a 15 minute job. Steve
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'82 911 SC |
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09-16-2007, 04:24 PM
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Join Date: Feb 2000
Location: Los Angeles
Posts: 13,333
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Why is it that a variable speed 120V switch is cheap, but the 12V alternative is crazy expensive? There are plenty of auto/RV/marine applications that call for them -- is there a technical explanation?
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Jack Olsen 1972 911 My new video about my garage. • A video from German TV about my 911 |
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09-16-2007, 06:16 PM
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Make Bruins Great Again
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Quote:
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-------------------------------------- Joe See Porsche run. Run, Porsche, Run: `87 911 Carrera |
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09-16-2007, 06:19 PM
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There are 12V dimmers, for marine or low-voltage lighting apps. But my non-electric-guy's brain doesn't know if the amps required for a 12V fan would burn them out.
Here's one. Here's another (the Skylark Low-Voltage slider). Any EE types who can tell me if they would work with a blower like this?
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Jack Olsen 1972 911 My new video about my garage. • A video from German TV about my 911 |
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09-16-2007, 08:13 PM
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Location: Southern California
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How about something like this: http://www.midwestmotion.com/servoamp/25a12v.html
12 volts. 25 amp capacity. Remote-mountable potentiometer. $187. Price break of $151 at 10 units. I have no pecuniary or other interest in this company...I just found the information with a Google search. 
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1984 Targa |
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09-16-2007, 10:03 PM
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FWIW - I do have the Kuehl variable speed fan control from Griffiths installed in my '89 and I have been satisfied with it In part I was attempting to reduce the noise associated with the AC since position 2 on the stock control wasn't fast enough and position 3 was too fast and too loud. The Kuehl product helped me accomplish this objective. I have no affiliation with Griffiths.
Regards, David.
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1997 Carrera 993 coupe - Slate Grey Metallic / Classic Grey 1989 Carrera 3.2L coupe - departed - Stone Grey Metallic / Silk Grey |
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09-17-2007, 05:15 AM
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Join Date: Feb 2000
Location: Los Angeles
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Do they sell the switch separately from the replacement motor?
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Jack Olsen 1972 911 My new video about my garage. • A video from German TV about my 911 |
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09-17-2007, 12:25 PM
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Jack,
Are you asking re. the Kuehl variable fan control? If so - I purchased the fan control by itself. Regards, David.
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1997 Carrera 993 coupe - Slate Grey Metallic / Classic Grey 1989 Carrera 3.2L coupe - departed - Stone Grey Metallic / Silk Grey |
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09-17-2007, 12:33 PM
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What do they charge for it?
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Jack Olsen 1972 911 My new video about my garage. • A video from German TV about my 911 |
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09-17-2007, 12:51 PM
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I think the fan control by itself is $300.
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1984 Targa |
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09-17-2007, 01:29 PM
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How about this one? 12 volts. 30 amps. $24.99 when it becomes available in a couple of weeks.
http://www.bakatronics.com/shop/item.asp?itemid=581
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1984 Targa |
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09-17-2007, 01:32 PM
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It looks promising. I wonder if it needs to be cooled by a fan?
I'm assuming you will be able to bypass the stock resister pack.
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Tom Hutchinson 80 Targa / 81 Coupe / 71 Targa (in Porsche heaven) My Garage Build: https://youtu.be/H0n_NwEQVbs "If one does not fail at times, then one has not challenged himself." Ferdinand Porsche |
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09-17-2007, 02:16 PM
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1984 Porsche Carrera coupe
993
Porsche
Max
1997 Porsche 911 Carrera (993)
