do you have a part# the old one is not readable, how do you know what type? if your interested I'd buy one of yours and pay shipping.

""TROUBLESHOOTING THE SENSOR CIRCUIT



The usual effect of a bad sensor string is “all or nothing” temperature control. If this occurs, the first thing to check is the connection for the outside air temp sensor under the left headlamp. If that doesn’t help, go to the next paragraph.



Remove the left side panel from the central console by moving the driver’s seat all the way back and down, and removing the two Phillips screws. and the parcel tray

Locate the setting unit, and remove the inner electrical plug. the setting motor is just above your right knee when seated

Turn ignition switch on, and move the temperature control lever to the lowest temperature setting. Use an ohmmeter to check the resistance between terminals 4 and 12 - the resistance should be approximately 3.7 Kohms.

Move the temperature lever to the highest temperature setting - the resistance should smoothly change to approximately 4.7 Kohms.

If the resistance is infinite (no connection), the sensor string is broken - the most likely place is the connector for the outside air temperature sensor. If the resistance is much lower than specified, there is a short circuit in one of the sensors or in the control head.""
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Thx, I appreciate any info you have for me Mrmerlin, thx for all the help you have given me!

OK I found the thermistors
Ok I found them .
I got the thermistors from www.newark.com
PN 121-102EAJ-Q01
Resistance 1Kohm
Thermistor tolerance 120%
Power rating 1mW/0 degree Centigrade
Resistance ratio 7.04
These are glass enclosed parts similar to whats in the system now for the outside sensor. They have 2 inch leads with some potting compound ,JB weld will work drill out the sensor it has glass in it so be careful, solder the wires onto the new part then insert into the sensor housing then fill with the potting compound try to put the harness wires into the tube so the new part wont get damaged ad pot the harness wires as well

found the specs for the thermistor in the Porsche Climate Control Spec Book, page 5: measured at the sensor wires directly...

At 32 degrees F.... 933 ohms
At 68 degrees F.... 588 ohms
At 86 degrees F.... 457 ohms

There are other measurements at the controller in this spec.

It looks like the price went up now they are 20.11 per part
IIRC I paid either 3.00 or 5.00 per thermistor new .
http://forums.pelicanparts.com/uploa...1278820405.jpg

Thx Mrmerlin, I will order 1 today, I should only need the one right? that is all that I see in the sensor itself. Thx again for all your work in helping me with the A/C.

Where did you get the Porsche Climate Control Spec Book? I have the factory shop manuals but not that one.

another poster on RL has assisted me with these numbers.
I started another thread on RL titled thermistor value so if you want to go check that out you can.
it wont crosslink to this BBS for some reason.
One thermistor is all you should need just be careful soldering the wires to the harness and then potting the new part into the thermistor housing,
you can use JB weld or any other potting compound just make sure to pot the harness wires as well so they dont break off the thermistor.

Just another update, found a used outside temp sensor for 65 and went ahead and got it, replaced the ducting from the sensor to the alt. All looks good just have to charge the a/c. I'm going to pull a vacume to see if it holds, if all goes well I will probably go with R12 and just make sure I use it during the winter season every few weeks to keep everything oiled and sealed.

R12
 

I just purchased 25 lbs of R12 to recharge my ac on the porsche..as well as my 92 toyota corolla(though it does not need recharging and probably never will)...for the record the R12 will last a lot longer than the 134a, and I feel it is colder. I can attest to the longevity of the R12 from my little 1992 toyota..the R12 in it has lasted the lifetime of the car..I have never had to service it for ac repairs at any time and the car has 350000+ miles on it...(actually the car has only broken down on the road once in its lifetime(a broken timing belt that had 150000 miles on it!...this is among the best cars ever built IMHO))I agree however that is must be cycled periodically and I cycle mine several times even during the winter months..it helps to clear a fogged up window if nothing else.

The Freeze 12 Option
 

I have seen quite an assortment of older vehicle R12 A/C systems successfully brought back to life using Freeze 12. Personally unless someone requests the trouble and expense involved in a full tilt conversion to R134 - I’ve found that using the Freeze 12 product is the simplest and most cost effective way to go. There were actually a few 928’s that required only some new “O” rings, a solid 29 inch vacuum pump pull down and a system recharge using Freeze 12 to make them into comfortable Texas summer time traveling cars. Even with tinted windows - Miss Purdy can be a rolling greenhouse when parked in the sun too long.

Michael :)

Freeze 12 Question -
 

I’ve had a couple of emails asking about using Freeze 12 - here are the basics. There are a couple of websites that offers the best price for Freeze 12 at around $8 - $9 per pound if ordered in the 30 lb bottles. By placing the larger bottle on a common digital bathroom scale, you can monitor how much Freeze 12 you use per vehicle. The one lb cans are convenient but you must be careful when switching between cans that you do not inadvertently insert a charging line full of air as you switch between cans. All of us do-it-yourselfers have probably made this mistake at one time or another.

Like someone has mentioned previously - what I think makes Freeze 12 the best alternative to R12 is that it is completely compatible to all pre-R134 systems. This includes the compressor oil, control orifice, hose material, “O” rings, etc…

Good Luck :)

Well another update, went to a friend and charged the old 928 with 3 cans of R12, it's in the 90's today and drove home with the vent temp in the 50's and a comfortable temp in the cabin. I hope that it charge holds and I can chill for a very long time. System held vacume nicely :)