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gjs
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Heat on then off
88 911. The heat can be working fine including all blowers. Then sometimes it is totally dead. When I pushed the control knob on the potentiometer it then came on and bliped off repetively, then after a while it will work again. According to Bently Manual when I test the potentiometer I have 950 ohms at postion 5 and it seems to be ok. I thought it could be the rear relay, but I don't see how putting pressure on the on/off control switch should affect the relay. When the unit is working and I unplug the rear relay even though the servo which pulls the cable works and just the blowers stop. When my system is out the cable control is out also. When it was beginning to act up the servo would kind of hunt around until it settled down. The dash temp sensor is 1.9 ohms resist as suggested by bently. The rear heat exchanger temp sensor does not register any resistance, so I assume it doesn't work, but dont think it's my problem. When system is working and I unplug this sensor it continues to work fine. My understanding of this sensor is that it doesn't allow blowers to work until the car exchangers warm up. I have the control box apart but connected on the floor of the car and it works fine now. I can't find the control box temp potentiometer on our hosts site. Any ideas? This has got me ready to jump. Thanks, Glenn
Ok now the relay is clicking and is probably the culprit. Don't understand why jiggling the control switch made it go on and off unless it was sending current to the relay and jaring it to work. Last edited by glennspiegler; 11-23-2008 at 08:26 AM.. |
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11-23-2008, 07:48 AM
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UnRegistered User
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Taking a guess here as I don't know how accessible the pot is in this case.
Get some electrical contact cleaner and spray in the pot and actuate it back and forth. Sometimes they can get a "dead" spot in them where the resistance goes out of the specified range. If the potentiometer is open (you can see the guts of it), use a pencil eraser to lightly clean up the face of the contact (pointer) and the wound coil.
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Bill K. "I started out with nothin and I still got most of it left...." 83 911 SC Guards Red (now gone) And I sold a bunch of parts I hadn't installed yet. |
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11-23-2008, 07:53 AM
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gjs
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Thanks Billy, please see addition to my above post. I do have the unit with the potentiometer out but don't see how to open it up. There is a metal band on the bottom that seems it would allow me access to the bottom. Edit: Got the wire off and will spray contact cleaner in it. Do think its the relay now. Beginning to have intermittant clicking with change in blower function.
Last edited by glennspiegler; 11-23-2008 at 08:57 AM.. |
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11-23-2008, 08:29 AM
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UnRegistered User
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There is a thread about troubleshooting auto heat, but I can't find it!!!
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Bill K. "I started out with nothin and I still got most of it left...." 83 911 SC Guards Red (now gone) And I sold a bunch of parts I hadn't installed yet. |
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11-23-2008, 09:08 AM
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UnRegistered User
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__________________
Bill K. "I started out with nothin and I still got most of it left...." 83 911 SC Guards Red (now gone) And I sold a bunch of parts I hadn't installed yet. |
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11-23-2008, 09:35 AM
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gjs
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Thanks, good info. I also will be ordering a controller. Learned how the system works. Will post the outcome when it arrives. This is truely a great site. Thanks, Glenn
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11-23-2008, 01:51 PM
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1983 Porsche SC
