orifice tube

[beamer]

can somebody tell me where the orifice tube on '90 markVII is, disconnected lines on both ends and can't find it. thanx

[LSRX101]

Look down in the evaporator inlet fitting. If it's not there its part of the liquid line (between the condenser and evaporator. To replace the orifice, you need to replace the line.

Why are you looking for the orifice tube?

[ekooke]

See here: http://www.corral.net/forums/archive/index.php/t-330728.html

If it's your intention to replace the orifice tube, that takes some real AC tech skill, while adding two more potential leak points. The BEST way to replace the tube is to replace the entire liquid line, with a new orifice tube pre-installed. A new line (with tube) is about $20 at any auto parts store. You'll also need the fitting tool, o-rings, lubricant, and a way to evacuate & test the system for leaks before putting new refrigerant & oil back into the system. Good Luck!

[WALTSAUTO]

Ford did two ways -- inlet line of the evaporator or high pressure line going into the evaporator down on the RH side frame rail coming out of the condensor --
if its in the line, the only other way to do it ( Thank you Ford ) besides replacing the line assembly is to cut the high pressure line going into the evaporator ahead of the pinch down area - pull out the orifice
tube and install an orifice tube kit which
has a compression type sleeve that contains the orifice and it splices right into the high pressure line -- as mentioned, you should have the necessary equipment ( vacuum pump / gauges / orifice tube puller ) before attempting this operation --
If the orifice screen is trashed then be ready for a component failure ( like the compressor ) to have been the culprit and unless you determine the cause of the blockage and flush the system, It will clog up again in short order and you will be right back at square one --
Good luck

[pro-five-oh]

I think all Marks use the built in tube in the liquid line of the A/C system.

The part is about $40, might just wanna replace the whole thing. I did when I converted to R134a.

[84mark]

i've heard of a special 'variable' o-tube that's recommended for 134 changeovers...?

[ekooke]

If you want to get into DIY AC stuff, THIS is the place to go: http://www.aircondition.com/wwwboard/

[Lee Joffe]

The variable orifice tube iis great, and works especially well with 134a changeovers. It senses low compressor speed, as at idle or moving very slowly, and the orifice tightens up for more of a spray into the evaporator, thus blowing colder. As compressor speed increases it returns to the normal size. One of the complaints about 134a changeovers is inadequate cooling at lower speeds/idle, and this thing cures that. :D

[NYC LS8]

I have an Adobe Acrobat file on the orifice tube, if you want. It's for an 87, but it should be somewhat similar.

If ya want it, post your email and I'll send it your way.

[Icarus]

quote:Originally posted by Lee Joffe:
The variable orifice tube iis great, and works especially well with 134a changeovers. It senses low compressor speed, as at idle or moving very slowly, and the orifice tightens up for more of a spray into the evaporator, thus blowing colder. As compressor speed increases it returns to the normal size. One of the complaints about 134a changeovers is inadequate cooling at lower speeds/idle, and this thing cures that. :D
Anyone I have talked to or read about says to avoid the VOV's...?! ...one more thing to fail and noone I've heard from has had any better performance with 'em...?

[LSRX101]

VOV's will help with cooling at idle on somewhat marginal systems like in the Mark VII, but only with R-12. They won't help on conversions. Fox body systems are marginal and overworked to start with. The Marks are the best performers and adapt well to R134a conversion. The VOV does add another point of failure.
If you have poor cooling on a stock R12 system, replace your fan clutch. If on a conversion, replace the fan clutch and add an electric fan.
Also, any time you open the system, replace the accumulator and charge into a vacuum.

[WALTSAUTO]

beamer -
Dont try this at home --
We are trained professionals on a closed course -- really - the 134 conversions are not bad, but you must have a pretty good working knowledge of these systems - you need to know about installing the conversion fittings / which oils to use and how much / what clutch cycling switch adjustments or replacement to make / what flush procedures to follow and how to vacuum / charge without a site glass etc -- incorrectly done A/C work can cause more damage then good -- unless you have some training and the equipment necessary to do the job correctly get some help
good luck - be cool -- ( pun intended )