Sockgoo Choi

My 928 S4(1989)’s A/C has not been working since early September this year.

Compressor did not worked, so the technician checked the power backwards.

1. He found no power from Anti Freeze Switch while the power is supplied to the switch.

2. So he removed the Anti Freeze Switch supposing it will not be difficult to get the replacement part.




3. During the process of removing the switch, he found the very thin pipe (red circle marked) linked to evaporator(?) was broken.





4. I searched for the part of Anti Freeze Switch from various websites who sells the parts, but I found nothing.

5. Will you guys please help me how can I take care of this problem?

Thank you in advance for your help.

Rob Edwards

Welcome, Sockgoo- You need a replacement freeze switch, part # 928 613 133 00, looks like they're about $45 from the usual vendors

http://shop.928intl.com/A_c-Switch/p...28-613-133-00/

or http://928srus.com/

Sockgoo Choi

Hi, Rob

Thank you indeed for your great help.
I will order it to 928 international.

kind regards

Sockgoo Choi

Hi, Rob

It seems that the 928 International link you mentioned is the part I need.
on the anti freeze switch the written number is 70.905.08.109

Sockgoo Choi

Does anyone know its part #?

The Forgotten On

That is the oem number, ignore it and go buy the porsche numbered part listed above.

dr bob

The switches have the original manufacturer's part numbers on them. Trying to find one in "OEM" livery can be pretty tough. Meanwhile, our vendors have sourced the correct switch and you can be sure it's exactly the right one.

For your mechanic and others playing along at home: The switch depends on that copper capillary tube, filled with liquid, to operate a small microswitch. The fluid expands with heat, pushing on a small brass bellows to close the switch. As the fluid cools with AC operation and drops close to freezing, the bellows collapses and the switch opens. The end of the tube passes into the air box through a small hole, and is retained by a small clip with a crew on the outside of the airbox. The copper capillary tube must not be bent with any sharp corners, as it will risk collapsing and blocking fluid flow. Worse, a sharp corner weakens the tube and risks a leak. When it leaks, it fails with the switch in the open position, and no compressor function. So use serious caution when removing or replacing the switch and especially that capillary tube.

ROG100

$39.99 and in stock.

Sockgoo Choi

dr bob,

Thank very much for your valuable advice. I got e-mail from Roger of 928sRus today, they have it in stock.

Kind regards

928NOOBIE

Hello
Resurrecting this thread to add reference material:
My evaporator had always been freezing up so I read the freeze switch had an adjustment....then I read there are 2 kinds of freeze switches....one that is adjustable and one that is not...I don't know if I agree with that...the switch in the above pictures has a screw head on the end where the electrical connections go. I have the other one, pictured below. I searched high and low for good pics of this thing and couldn't find any so am providing.

To adjust I went approximately 1/4 turn clockwise then road tested. The air coming out of the vents was absolutely frigid with fan setting of 1 and the temp slider to the coolest setting and running on the highway on 80 degrees or so but with pretty good humidity I could not detect a reduction in air volume coming out of the vents....several times I turned the fan to 4 to see if I could tell that way and it appears that so far the adjustment worked but time will tell...not quite ready to put Jerry's cowl cover back just yet...

The first pic below is the end of my freeze switch with the electrical connections:


This end is facing the drivers' side *LHD - 2 wire connection, standard for both switches....visually if you compare to above posts this end would have the screw head and be a brown plastic or similar type of material.

Pic below is other end of switch...the small phillips head screw you see is the adjuster for this type of switch. Turning it clockwise will raise the temperature that the switch cuts current (which is what I needed in my case; given mine has been freezing) to the compressor. I have the copper tube that goes over the end of the capillary probe so its correct depth-wise (fits over end of capillary probe and tapers outward so you can only push the probe in a certain amount) where it goes into the evaporator chamber.


Small phillips head ....turn clockwise to raise temp. to cut power to the compressor. As a friendly reminder, for those that still have this circuit as a load bearing one; the freeze switch can burn out from current over-draw as the climate board relay...happened to me before I added the relay under the hood to power the compressor and updated pusher fan thankfully this switch is nowhere near the cost or PITA as the climate board relay fix.

With this properly adjusted and the relay under the hood taking load off this circuit and powering the front pusher fan and the A/C trigger wire for the fan controller that runs the 2 main rad fans everything properly cycles with the compressor, courtesy of our correctly adjusted freeze switch on a trigger-level (very low load) circuit.

I hope this info helps as we continue through spring and tackle our seasonal work to get our A/C's optimized for the upcoming warmer weather.

Alan

Its not the freeze switch that usually dies - its the relay in the head unit. Taking the load off that relay is still a good idea (contacts are undersized for the load). For model years that have a suppressor relay never remove it from the CE panel unless you want that head unit relay to die (even sooner)...

Alan