Need P/N for A/C temp switch/cap tube

curiousone940 · curiousone940's Garage

I'd like to replace the A/C temp switch/capillary tube before the weather starts warming up again (evaporator is freezing up)....I've found what appears to be a Porsche P/N for what I need, but I'm not certain. On the P parts CD I am using, there is a part called the "thermo bi-metal switch", P/N 911-618-151-00. This P/N is within the A/C/evaporator section, however, the actual part itself is not shown in the accompanying photo. SO, can someone out there confirm that I have the correct P/N and approximate price of same. Appreciate your help.

syncroid · 02-01-2006, 04:41 PM

If I am not mistaken, I believe the capillary tube is part of the temperature switch in the center console. The part # for that is 911 613 121 01 and has a retail price of $84.42 You have to look in the electrical section of the program to find the part.
I hope this helps.

DonMo · DonMo's Garage

It is part of the dash AC temp switch. The bi metalic switch is down on the floor board. It is really a pretty generic part in the AC world. I bought a replacement on ebay for under $10 bucks.

curiousone940 · curiousone940's Garage

Syncroid----thanks for pointing me to the electrical section. I found the part number (simply referred to as the "temperature switch"), however, the photo simply shows the switch...no capillary tube shown. Since I've not actually pulled the switch, I don't know if the capillary tube is part & parcel of the temp switch or not. If not, I suppose I can hustle up an appropriate cap tube from a local AC supplier. Thanks again for your help.

syncroid · 02-01-2006, 05:14 PM

I'm almost positive that its part of the switch. Its just been a few months since I have pulled one out.
I'm glad the info helped you out.

don911 · don911's Garage

This is pic from my 87.

kuehl · kuehl's Garage

M. Morrison,
I've seen more of these switches fail in the "open" position, meaning they fail typically when the refrigerant gas in the cap. tube escapes in which case the compressor won't operate. Before you go through all the fun of replacing the unit in an 89 console, try testing the unit. Most icing problems we see are because the alumn. cap. tube. is not making good contact with the evap. coil.

Get yourself an aerosol product that "freezes", such as circuit test freeze stuff or whatever someone can suggest (such as ice and salt, etc), start the system, pull out the alum. cap. tube from the evap core and freeze it, compressor clutch should break on positive test result.

Otherwise, the cap tube is part of the a/c thermostat switch assy.

curiousone940 · curiousone940's Garage

Hadn't thought of that, but it sounds reasonable...I'll give it a try and let you know what happens. Thanks for the tip!!

kuehl · kuehl's Garage

de nada
stay kuehl!

curiousone940 · curiousone940's Garage

Got the aerosol freeze stuff (Radio Shack by the way) and tried it this afternoon on the cap tube (AC on with about 75 degree outside air temp)....with the temp turned all the way down, I had to spray several seconds to get the compressor to cut off....as soon as it warmed up, the compressor came back on (as it should have). SO, I lightly sandpapered a layer of oxidation/crap (???) off the cap tube and tried the spray freeze again. This time, I didn't have to spray nearly as long in order to get the compressor to cut off. Is it just my imagination, or is it possible that this layer of stuff on the cap tube may have acted as an insulator of sorts....preventing the evap temps to reach the cap tube/temp switch (thereby allowing the compressor to run on longer and creating a freeze up in the evap)??? Also checked to make sure the cap tube was making good contact with the evap coils as well. Bottom line...I think I'll wait until later in the spring when the weather warms up and I'll see if I get a repeat of the evap "icing up" again BEFORE I needlessly replace the temp switch/cap tube.

kuehl · kuehl's Garage

curiousone940,

Sounds like poor contact of the aluminum capillary tube in the evaporator core. Suggest you read the passage
"The AC Temperature Switch - An example in detail with a typical 911 Porsche" located at this url:

http://www.griffiths.com/achelp/achelp4.html

curiousone940 · curiousone940's Garage

Thanks for the informative article...I'll re-check and confirm proper positioning of the cap tube on the evap coils.

RandalJ · RandalJ's Garage

Note on the Carrera A/C temp switch: Factory replacements didn't fit when I tried to replace my switch a couple of summers ago.

The factory replacement was slightly too big, and the spindle for the knob was in the wrong place. Though I could force-fit it into the console, the spindle did not align to the hole in the fascia. Not even close. Relocating the hole was not an cosmetically good option.

Porsche (or Bosch) must have discontinued the original design, and were apparently serving up the closest equivalent as an "equivalent replacement".

Perhaps they have redesigned the part since then, but be warned...

I found in my case that the switch housing was cracked, not allowing the bellows to trigger the switch to the compressor. I fixed the housing, and it worked fine. You may want to make sure that the integrity of the housing on your switch is OK, if you are still having problems. You can do that without going to the trouble pulling the temp sensor tube out of the firewall (or worse yet, fishing it back in... )