orifice missing?

94 Exp - dye test showed leak on comp seal. In process of replacement there is no orifice tube at all. System is clean inside.

Is it possible this was not installed by previous tech? Is it possible it got blown into evap? What if it did?
Thanks

If the a/c was working then you had the restriction in the evaporator to make it work (you had an orifice tube).. which means most likely the orifice tube was blown in to the evaporator.

Our old a/c system had that issue.. One day the a/c just stopped working with almost no pressure differential between the low and high side. I thought the orifice tube broke. I opened the system and couldn't find the tube. I called a neighbor (mechanic) and asked him what would he do. He said if it came into his shop they would start with adding an orifice tube and letting the customer know that eventually they may need to replace the evaporator. I installed a new one and all was fine...

Fast forward 6 years or so.. I had to replace the evaporator since the grinder got a little friendly with it. I changed the evaporator and while doing so (changed other things like you normally would do) we put in a new orifice tube. While charging the system I heard a pop and loss the pressure differential. I was not a happy camper and I didn't have time to rip everything aparta gain. I then crimped the tube that the orifice tube sits in myself using a pair of pliers and put in a new orifice tube. The system has been working really well now for over a year.

I don't know if it matters but I use the severe duty Variable Orifice Tube (aka VOR) instead of a standard one as it gets to 105F+ in the summer. That means the idle pressure is higher than it would be with a normal orifice tube.

~Mark

Where did you get the severe duty variable orifice tube/valve? I've been looking for one to use instead of a blue/red FOT when I convert to R134a, which should be soon, but can't seem to find them anywhere, let alone one for a Ford or Explorer.

Did you replace your factory R-12 hose assembly with a R-134a barrier hose when first converting, or just convert the schrader valve to a R-134a fitting?

Oh, and in what way did you crimp the orifice tube to prevent the new VOT from blowing into the evaporator? Sounds like I'll be doing that initially rather than after it blows through the first time.

Years ago, We blew a a/c line (it used to run behind the motor). At that time we changed the hose to a r-134 safe line and flushed the system and put in the first VOR. (aka VOT)

I get them from a local parts chain called Merles.. they supply the shops in the Tucson area..

I never looked online for them.. Usually the sever duty ones say for Phoenix, Az.

Worst case, I can pick one up for you and drop it in the mail (priority mail would be $5 and you would have it in < 3 days). There is a Merles near my work, so no markup.. Just charge ya what they charge me + $5 for shipping.

As for the crimp.. I just use pliers that have the notches in them that would normally grab a nut. I just put it where the factory crimp was and squeezed a little. Then I rotated 90 degrees and crimped again etc.. I think by the time we were done I had a crimp about every 45 degrees.

The pliers look something like this.


~Mark

Did you convert the line & compressor to a system from a '94, or a r134a barrier hose made for a '92? I'm hoping I can get a r134a barrier hose with the right fitting that runs the same as my stock '93 since I'm not going to change the compressor just yet, just the accumulator and hose, flushing the rest. Not sure if they only make barrier hoses for everything now, or still r12 hoses with r12 fittings for r12 systems.

NAPAonline has what they call an "Automatic Adjusting" orifice tube...$33 bucks for the 95-105 degree one, $60+ for the "severe duty" one above 105 degrees. Kinda expensive compared to their $2.49 stock replacement. Do you remember what yours cost?


Maybe I don't need the severe duty ones (temps are usually 80-90 but rarely 100), but could you call or see if they offer a VOT/VOV in a non-severe duty version next time you're there? No rush, it'll be awhile before I get to this.

My only concern on a VOT/VOV is getting the right size, since a smaller diameter than stock tube would obviously be the reason it'd get sucked into the evaporator.

I've pretty sure I changed the compressor when we changed that hose.. I just told the counter guy I need a compressor and a hose for a '92 that I was converting to r-134.. He had it at my neighbors old shop the same day...

As for the orifice tube.. IIRC, the sever duty one was expensive.. I believe it was close to $40..

I'll can give them a should tomorrow and ask my counter guy. I only deal with one person now, and he is great..

edit: and with the temps you say you see, I doubt you need the server duty one.. just the regular VOR should work. The Sever Duty one did drop my a/c temp at idle a few more degrees (maybe 5), but when I ran the non severe duty one it still worked well. I never tried it in 110F+ though.

~Mark

I've been able to find the variable orifice tubes online now, RockAuto, among others, now has them.

Still curious about whether theres an actual R134a barrier-type hose or hoses with fittings for a 93/94 system, though.