AC Switch Problem

ruby911 · ruby911's Garage

Last night, I decided to tinker with the shifter in my '84 so I removed the console. I noticed what originally looked like a white broken wire that had at one time been connected to something. Upon closer inspection, it actually turned out to be what looks like a tiny little copper tube that appears to have been attached to the temp switch on the AC. Am I right about this? I had to get the car back together last night so I could drive to work today, so I was unable to do much more diagnostics on it, but the tubing looks like it runs behind the passenger footwell. Additionally, I noticed this morning that when I turn the AC fan speed switch on, it does not appear that the compressor kicks on.

OK, here comes the dumb question.....can I assume these two issues (broken tube and compressor not kicking on) are related? Does this mean a new temp switch for me?

Thanks, Farrell

al_911 · al_911's Garage

You now need to replace the AC Thermostat Switch…I replaced my switch about threes weeks ago, I got mine from Griffiths, it’s not a perfect fit you may have to modify the inside section of the console where switch goes to make it fit. Also, the new switch does not come with the white insulation; you have to use the old one. There is also a tube that slides inside the evaporator, later the probe coming from switch goes inside the tube.

Mitch Leland · Mitch Leland's Garage

I used Griffiths Temp switch, Al is correct it does take some fitment... However it's not a big deal. Also I used a 3 pair telephone cable jacket for the insulation if your insulation is not reusable. I just stripped out the 3 pair cable and slid the jacket over the tube. If you want to spend some extra money Griffiths variable fan switch is the way to go. BTW don't forget all of these up grades are available through our host.

I would also recommend using Giffiths compressor indicator light. It allows you to know when the compressor is operating in the cooling cycle or when it's in the fan mode, it's a nice up grade and easy to install. For more information see my Tech Article on the PP Tech Section:
http://www.pelicanparts.com/techarticles/911_ac_1984/911_ac_1984.htm

ruby911 · ruby911's Garage

Thanks for the quick feedback guys. What exactly does that long tube do?

Tigerrat · Tigerrat's Garage

It's a capillary tube to sense the temp. of your evaporator.

ruby911 · ruby911's Garage

So, would the fact that the tube is broken be causing my compressor to not kick on, or do I have a separate problem?

Barrpete · 05-08-2009, 06:22 AM

Quote:

Originally Posted by ruby911

So, would the fact that the tube is broken be causing my compressor to not kick on, or do I have a separate problem?

Correct. That tube is filled with an inert gas that contracts when the evaporator gets too cold. when the gas contracts it opens a set of contacts inside the switch to shut down the compressor so the evaporator doesn't freeze up. If that tube is broken then all the gas has leaked out and you now need a new temperature switch. As a temporary fix you can just jumper the two leads together and bypass the switch completely.

ruby911 · ruby911's Garage

so, I can just attach a small wire between the two posts to get cold air until my new switch arrives (and obviously run the risk of freezing things up)? Is a 'jumper' that simple?

Barrpete · 05-08-2009, 07:20 AM

Quote:

Originally Posted by ruby911

so, I can just attach a small wire between the two posts to get cold air until my new switch arrives (and obviously run the risk of freezing things up)? Is a 'jumper' that simple?

Yup. You can simply take a short piece of wire and crimp a spade clip on each end and plug it into the 2 leads to bypass the switch.

Mitch Leland · Mitch Leland's Garage

Quote:

Originally Posted by Barrpete

Yup. You can simply take a short piece of wire and crimp a spade clip on each end and plug it into the 2 leads to bypass the switch.

I wouldn't do that, you stand the chance of having the evaporator freeze up which could damage the compressor since your compressor doesn't have a overload safety pressure switch. It's much like having a blown fuse and replacing the breaker/fuse with a piece of foil, it's a bad substitute.

Replacing the switch is a pretty easy DIY project and not too expensive...

Barrpete · 05-08-2009, 09:58 AM

Yes you do run the risk of the evaporator icing up. That's why this is a TEMPORARY fix only.

ruby911 · ruby911's Garage

Thanks to all.....just ordered a new switch.

88911coupe · 07-17-2009, 08:25 AM

I just pulled the brass tube off the end of my capillary tube but can't tell if there are any leaks in it. It "appears" to be undamaged but is there any simple test that I can do to confirm that it has not been damaged? It did have some mild bends but no true "kinks".
TIA

Tigerrat · Tigerrat's Garage

Buck, I'd probably disconnect the wires on the switch, check continuities and stick the end of the tube in a glass of ice water and see if the continuity changes. Never done it but that's my 2 cents.

PS Did you get that engine back in? Ken

88911coupe · 07-17-2009, 10:02 AM

Ken,
Thanks, that's what I needed. And yes, I got the engine back in and other than a couple of oil leaks I'm working on, it seems to be running fine...knock on wood!

Tigerrat · Tigerrat's Garage

Great. Yeah, I ended up with a tiny leak, a drop after each run, that I'll live with. Ken

JFairman · 07-17-2009, 10:19 AM

Pelican sells the origonal manufacturer AC temperature switch for $47.25, and it comes with the white vinyl insulation around the aluminum capillary tube.
E v e r y t h i n g from Griffiths is insanely overpriced... and if the capillary tube insulation is missing it's not even the correct part.

Very easy to install if you pull out the rubber grommet in the lower dash bulkhead it goes through first.
Reuse the 4" hollow brass tube that inserts into the evaporator to protect it.

copy and pate this pelican part number into the search box at the top left of the page. 911-613-121-01-M145

A/C Temperature Switch, 911/911 Turbo 1974-89
$47.25

86 911 Targa · 07-17-2009, 11:08 AM

Buck,

Tigerrat is correct.

When you put the evaporator tube in the ice water, look at the diaphram in back of the
switch. It should expand and contract when you remove/insert/remove the evaporator tube
from the ice water thereby opening/closing the relay.

Good luck,

Gerry

ertech · 07-18-2009, 04:34 PM

just got the part pelican sells and it is way to big and does not fit where the switch is . anyone order one from Porsche ?is it the same as pelican
see the pic on how small the original one is compared to the new one .I tried all and it is way to tight
what should I do?
Thnaks

JFairman · 07-18-2009, 04:56 PM

I cut the bottom of the plastic box out. I've read here others did that too.
You can't see it when it's installed anyway. Working AC is important to me in Florida.
That allows the AC switch to drop down so the bottom of it is flush with the bottom of the box. The same as the thickness of the plastic along the bottom you remove.

It's alot easier reinstalling the switches with all the short wires plugged in with the bottom cut out of the box and useless center piece removed.
With the center pice removed that opens up an area to put in a small indicator light or other small switch.

Install it so the knob points to the right place and be careful to not kink the capillary tube and it's good.