Farrar's car blog

[dvonk]

great news! heres hoping that fixed the problem.

[Bitsyncmaster]

Nice job Farrar. That would be a good video to keep to show first timers how AC work is done. You make it look to easy (no swearing).

[Ron]

Oops...

ac-vov-valve-position.jpg
(RE: orientation, not depth)


Image1.jpg

[DMC5180]

So much for the NO swearing! I can see Farrar now followed by


Yeah, NEW hose connections make it look so simple. You should have done a video that showed Removing the Connections of the old hoses and installing the new ones. I'm sure there was some swearing going on then.

[Farrar]

Nice job Farrar. That would be a good video to keep to show first timers how AC work is done. You make it look to easy (no swearing).

This is why I annotated it with wrench sizes, etc. -- with the systems now turning 30+ years, and R-12 becoming prohibitively expensive or unavailable in some areas, I imagine a lot of people will start working on their a/c and they need to know it is not as daunting a task as it may initially seem.

Oops...

ac-vov-valve-position.jpg

I am familiar with that photo, as the "variable orifice valve" from John Hervey is the one I have installed. According to Welmoed Jonker, the photograph shows the VOV pointing in the opposite direction of how you actually install it -- he mentioned this in another a/c thread here on DMCTalk. Just to make sure, I looked it up.

(By the way, GM calls them "expansion tubes," Ford calls them "fixed orifice." But no matter what they're called, all orifice tubes work the same way: they have a filter screen to trap contaminants, and a calibrated opening to meter refrigerant flow.)

In theory, you could install the orifice tube backwards and it would still work -- it has a filter screen on both ends. But the only way I could get mine to "click" into place was by installing it backwards from indicated in the photograph.

(Edit: Just in case I screwed it up, I do have an NOS orifice tube ready to install.)

great news! heres hoping that fixed the problem.

Thanks! Hope springs eternal, right? I will know as soon as I am done with my coffee -- going to head out to the garage and check the gauge. At 8:23am it's only 82°F so I can walk into the garage without getting too sweaty before breakfast.

P.S. -- One thing I forgot to mention in the video is some info I got third-hand: someone told me that Dave Swingle once told him that a common place for an a/c leak is at the low pressure switch. I can see how this might be the case: although it's a 5/8" fitting that you can easily get a wrench on, it is made of plastic (white nylon perhaps?) so I imagine most people hesitate to tighten it down very hard. Also, it could be that they forgot the O-ring, just like I did the first time.

Edit: Ah, you guys are too quick! Two replies in the time it too me to write one!

[Farrar]

You should have done a video that showed Removing the Connections of the old hoses and installing the new ones. I'm sure there was some swearing going on then.

I didn't have a video camera back then, but the only fittings I had difficulty with were the ones on either end of that short bent pipe where the orifice tube goes in. I opted to remove the evaporator with the hose still installed.

[DMC5180]

Please show us where it states the VOV goes the other way.

[Ron]

This is why I annotated it with wrench sizes, etc. -- with the systems now turning 30+ years, and R-12 becoming prohibitively expensive or unavailable in some areas, I imagine a lot of people will start working on their a/c and they need to know it is not as daunting a task as it may initially seem.
I am familiar with that photo, as the "variable orifice valve" from John Hervey is the one I have installed. According to Welmoed Jonker, the photograph shows the VOV pointing in the opposite direction of how you actually install it -- he mentioned this in another a/c thread here on DMCTalk.

Well, I believe you need to look it up again (while noting evaporator mounted VOVs mount backwards from condenser mounted VOVs). Or, consider that the larger filter is there to catch "trash" from the compressor, or, where the "hook hole", if equipped, will be for a remover to grab.

(Just to make sure, I looked it up, ...)

Link???

(By the way, GM calls them "expansion tubes," Ford calls them "fixed orifice." But no matter what they're called, all orifice tubes work the same way: they have a filter screen to trap contaminants, and a calibrated opening to meter refrigerant flow.)
In theory, you could install the orifice tube backwards and it would still work -- it has a filter screen on both ends. But the only way I could get mine to "click" into place was by installing it backwards from indicated in the photograph.

(Edit: Just in case I screwed it up, I do have an NOS orifice tube ready to install.)

Some call it an "orifice tube", or "fixed orifice", or "fixed orifice tube", etc, and some to confuse things, "expansion tube," all the same thing. Others use an "expansion valve". These are two totally different units which look/work nothing alike. Yes, there is a filter on both ends of an orifice tube, but they are different sizes.The larger one (where a hook hole is) goes to the outside (away from the evaporator). The small one is a backup for what may pass through the tube (goes inside evaporator tube first). You might get away with putting a fixed orifice in backwards but, I would not try it with a variable type.

===========

You must have been replying while I was editing my last post- If your condenser has a groove or butt where you put the o-ring to remind yourself in the vid...you have it in the wrong place.

[Farrar]

Link???

Link!!!

Thanks be to Google.

No offense Ron, but your post came across as a little know-it-all-ish. Have you been taking lessons from David Teitelbaum?

Edit: After studying Fig. 23 on page N:03:02 of the Workshop Manual, it looks like the short end of the orifice tube does indeed point toward the evaporator. (Although I didn't catch it on film, I had installed the long end in that direction.) I tried searching for photographic evidence of either direction of installing it online, but turned up nothing, so I will have to trust the sometimes-wrong Workshop Manual. This will make installing the bent tube a bit trickier, but shouldn't be too bad. I don't have an orifice tube removal tool, but if it's needed I can rent/borrow one from the nearest parts house.

[Farrar]

Good news: the system held vacuum for almost 24 hours without the gauge budging. BTW, I didn't wrench like hell on those fittings -- the O-rings do the sealing. I might even put some anti-seize compound on the fittings the next time I am in that area.

Speaking of which -- I relieved pressure on the system (by slightly undoing the low-pressure sensor until air leaked in through the Schrader valve) and went about removing the VOV which, naturally, left its white plastic bit inside the tube. The regular orifice tube extraction tool assumes two things: 1.) the thing isn't broken, 2.) it was installed correctly in the first place. So I have ordered a tool for removing broken orifice tubes (cost a whopping $15), which should arrive later this week. I'm off to work now in the pouring rain, so the next time I will have a chance to work on the car is next Saturday anyway, and the tool will have arrived by then.

Until next time...