bd0nalds0n

Hi Jim,

Two questions: In taking a look at the guide tube, is the screw holding it on the left of the tube or the right? I took mine out today, and the hole for the guide tube and screw are virtually identical in size. So you can re-install it either way. I think the screw goes in the right hole and the guide tube in the left. But I want to be sure.

Also, once you got the capillary tube in between the fins--how much space did you have uncovered by the sheathing? I got my capillary tube pushed in so there's basically no unexposed tube between the sheath and the guide tube.

I adjusted my freeze switch a bit warmer (clockwise is my bet for the direction to turn the adjustment screw to adjust switch opening to a hotter temperature) today. It now seems to cycle the compressor, but I still have quite a bit of water under the car. It may just be that the hose is clogged and not draining properly. Can the hose be switched out by removing the dash undertrays and side panels of the console? Or you you need to pull the center console and/or dash?

I would like to think it would be relatively easy to access and switch out, but hope springs eternal.

I really had no idea this would be such a controversial topic. You just never know.

jcorenman

The screw is on the right side as you face it, i.e. on the driver's side for a US car.

By "sheath" you're talking about the plastic sleeving over the capillary sensing tube? The length of that looks a little arbitrary, what I did was remove the guide tube, slip the capillary tube into that until the tip just reached the end, and then marked that (on the outside) with a felt pen. Then installed the guide tube and peeked into the evap housing (by pulling back the rubber boot between blower and housing) and noted that the end of the guide tube was resting against the fins. Then re-insert the capillary tube. That's when I found that the capillary tube didn't want to go any further, until I pushed the fins around with my "special tool" (the bullet-nosed piece of welding rod). In my case it then went another 1/2" or so between the fins, and probably ran into the evap tubing. But that's plenty, the sensing part of the capillary tube is the last couple of mm.

It's still apart, I'll go grab some pic's and update this.

A lot of condensation is normal in humid climes, when you reduce the temperature of warm air then you reduce its ability to carry water and the excess water condenses onto the evap fins, collects in the bottom of the evap housing and runs out the drain--- which exits under the car above the back end of the bellhousing. If the tube is plugged then it collects and spills onto the passenger's feet in a left-hand turn, so listen for a shriek from the co-pilot.

It's when it is NOT dripping that you've got an issue-- that means the moisture is freezing and turning the evaporator into a block of ice. And ice doesn't drip until you shut off the compressor and it starts melting.

And hey, it is all good- the road isn't always smooth and I learned some good stuff here. Back in a few minutes with pictures.

bd0nalds0n

It can also spill out on the driver's feet on a right hand turn. Ask me how I know.

jcorenman

Brian,

Here's a couple pic's of the guide-tube showing the attaching screw and the capillary-tube sensor in place, also showing how much sleeving is left.
(And apologies for the dirt, clearly not up to Dwayne's standards!).



The freeze-switch is in the upper-left, then the plug for the blower resistor-pack, then the guide tube, then the expansion valve block in the lower-right:



Then, "peeking" into the evap housing with the guide-tube and capillary-tube sensor in place. The end of the guide tube is a few mm from the evap fins here, before the cap-tube was pushed in the end of the guide-tube was just touching the fins.



Here's what the guide-tube and capillary tube look like when removed, in the same relationship that they were in when installed. The insertion depth between the fins looks more like 3/4" here, but I'm sure that is not critical.



Here's the "special tool" that I made, to make enough space between the fins for the capillary tube:



And here's the attachment I made for our shop-vac, for cleaning the evaporator fins. This worked pretty well, various attempts without the brush weren't as successful and tended to bend the fins.

bd0nalds0n

Very creative work. Thanks for the pics. For those of us without welding rods, we could probably use a piece of wire coathanger.

Okay, well, at least I've got the guide tube installed correctly, and I had some initial resistance pushing in the capillary tube, but I wiggled it a bit and it went in further. I would say closer to 3/4" and 1" so I'm happy to see your comment both amending the 1/2" statement plus the addition that "it probably doesn't matter."

I should probably take a closer peek at the evaporator just to be sure.

Frankly, in another couple weeks, it won't matter until next summer except for those rare occasions I need defrost which won't be on long enough for icing to become a problem.

Thanks for the pics, Jim. As far as I'm concerned, you get the 928 forum employee of the month award along with the good parking space up front.

jcorenman

The parking space up front? Cool!

Sue is still mad about her toothbrush, however. (At least I gave her the handle back... brush delete).

I put a couple of additional pen-marks on the capillary tube before putting it all back together, at 1/2" and 1" past the end of the guide-tube. (The guide-tube is 3.5" overall length, so I marked it at 3.5", 4" and 4.5"). I gave the capillary tube an extra wiggle and it went a bit further, just to the +1" mark-- about the same as you got. So for sure it is reading the temp of the evap core and not just the air going by.

Earl Gillstrom

Jim,

I just measured the guide tube/capillary tube on an '87 that I am working on. It looks original. The capillary tube sticks out ~1.5" past the end of the guide tube and looks very similar to ones that I have worked on in the past. I doubt that it is too critical and 1" may be fine. I am not sure how you would know if it is touching the evaporator core, but it is probably touching the fins. Makes me wonder if this inaccuracy is why some of them need adjustment when new. Now that I think about it, that may be the answer. In this day of sealed, non user adjustable parts, why would they manufacture this unit with 2 user adjustable screws?

bd0nalds0n

There are two adjustable screws? My freeze switch only had one.

jcorenman

That all sounds right. I just checked our S4, the capillary tube was installed properly (i.e. stuck between the fins) and was sticking out beyond the guide tube about 1.25". Pic's and details to follow.

One is on the end opposite the terminals, a small phillips. This adjusts the temperature, righty-warmer-lefty-cooler (I think). The second is on the bottom (as mounted) under a white cover, and sets the on/off temperature differential. Try not to mess with this one, I did by mishap and it was a real PITA to get it back to a reasonable setting.

Cheers,

jcorenman

OK, to follow up on my previous: I dug into the freeze switch on our S4, 75K miles and owned since new. I changed some o-rings last summer (rear AC circuit was leaking under the pass-seat), flushed, vacuumed and recharged (by weight) with R12, but the freeze switch is just the way Fritz assembled it. The AC runs quite well except tends to freeze below around 90F (airflow drops and gets warmer).

The first pic below shows the same "peek" into the evap box, guide tube is about 1/4" short of the fins and the capillary tube is well buried into the evaporator. (It is also pretty clean as these things go, just some leaves and dirt in the bottom).



The capillary tube was neatly bent downwards and led back to the freeze switch under most of the other wiring, and behind the resistor-pack cable.



I then pulled out the capillary tube and measured it, about 4.75" to the bend. The tube is 3.5", there was about a 1/4" gap to the fins, so about 1" was buried between the evap fins.



This pictures shows the sleeve detail, with shrink tubing securing the yellow (teflon?) sleeving to the capillary tube. The replacement (in a Porsche box) was different, clear loosely-fitted vinyl sleeving.



So why was the S4's AC freezing? I did the icewater test and the switch never opened. So I fiddled with the temperature adjustment (adjust-screw was hidden inside, accessible through a hole in the end opposite the terminals) and it seemed to open and close rationally. I think it is opening around 36F, we'll see what happens.

I also concluded that my "special tool" was useless. The capillary tube didn't want to go back between the fins, but a much simpler/better technique was to loosen the guide-tube screw a half-turn so it can flop around a little, then wiggle the capillary tube while gently pushing-- it readily finds its way between the fins and past the evap tubes. Then tighten screw.