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View Full Version : expansion valve diagram - does this exist?


Jim Petri
09-11-2004, 08:20 AM
recently flushed my A/C system after installing a "new" compressor (old clutch gone awry). began looking at in-line expansion valve and noticed that previous owner had taken it apart. i don't think it was put back together correctly because the two spring loaded plungers were working in opposite directions. anyone know of a diagram for the correct expansion valve installation?

M. Mayben
09-11-2004, 12:39 PM
Jim,

I have many, many, MANY line drawings, cutaway drawings, etc. of different types of Thermostatic (or Thermal) expansion Valves as I retired as an FSE for Diesel Kiki/ZEXEL/Seltec/TAMA, a MAJOR world class manufacturer of mobile HVAC systems and components. I've got many sources in my collection regarding the subject device.

I don't have scans on any of this right now as I have just recently gained access to all my archived technical quapo after moving into our new shophouse. Long term project is to scan in all the info which might be of use to folks here on the BB.

If you will backchannel me a fax number, I'll be glad to fax ya what you need.

If the TXV you're needing info on is a common "L" type unit (OEM/aftermarket IH application), I'll send that to ya first. I also need to know if it is "internally equalized" or "externally equalized". An externally equalized TXV has a second very small diameter copper tube with a swivel nut attached. This is in addition to the "sensing bulb" which has to be firmly attached with hard contact on the evaporator refrigerant tube. Let me know EXACTLY what type of valve drawing you need and I'll do what I can for ya!

The TXV we're refering to is a very common application available from most any parts jobber. If the valve has been taken apart (as opposed to just removing it from the evaporator), it will be IMPOSSIBLE to put it back together and adjust it to the proper set point without placing it on a calorimeter/test stand. EACH TXV is individually calibrated at the point of manufacture for the type of refrigerant to be used. Ya might be better off just buying a new one which has not been screwed with.

Jim Petri
09-11-2004, 01:03 PM
thanks so much for the info. After reading your response, I'm not exactly sure what it is that I took off of the vehicle. It is a two-piece fitting. One piece has a spring loaded plunger integrated while the second piece has a spring loaded plunger that is removable. These two pieces are attached to the hose between the condensor and the evaporator (thus my inclination that it is the expansion valve). The pieces are then connected using the integrated fitting on one of the pieces (the one with the integrated plunger). I'm not sure that it was put on correctly, i.e. should the plungers be open all the time. If it is installed so that the plungers "plunge" in the same direction, one scenario is to install so that as the fittings are mounted to the hose(s), the plungers are opened. The second scenario (mounted 180 deg opposite) does not allow for the plungers to open during installation. I believe scenario one is correct, with the plungers mounted so as to "plunge" in the same direction, i.e. plunger #1 pushes directly on plunger #2, thus creating an orifice.

I'm looking for the answer as to how this should be mounted.

thanks
:)

M. Mayben
09-11-2004, 06:09 PM
Jim,

The "TXV" has to be mounted VERY CLOSE to the evaporator inlet on BOTH an IH OEM a/c system and ANY aftermarket a/c system evaporator designed for an IH application. That's were the "pressure drop" occurs which makes it all happen!

AND..I'm assuming we're talking about the Scout here that you've referenced in your sig.

As for the fitting you've described, it sounds like some kinda "quick connect" fitting. Similar to an pnuematic coupler or hydraulic coupler????

In a "TXV"-type a/c system (as opposed to a "cycling clutch orfice tube (CCOT)"-type system, there should be a hose/pipe (high pressure side) coming out of the condenser and then entering the INLET side of the receiver/drier. From the receiver/drier OUTLET side, the high pressure hose/pipe should go to the TXV INLET, the TXV OUTLET then is attached to the evaporator inlet pipe/pigtail. Evaporator OUTLET goes to the compressor INLET side (low pressure side or "suction" side). Compressor high pressure side (discharge) is connected to the condenser INLET fitting. That's the "refrigeration loop" of a TXV system.

CCOT systems which use an "orfice tube" and "accumulator" (instead of a TXV and receiver/drier) were never an OEM item for IH. There were NEVER any CCOT aftermarket systems manufactured for ANY vehicle which I am aware of as they have to be very "platform-specific" in their design, the TXV system was the system of choice for ALL aftermarket manufacturers.

It sounds to me that what you might have is a type of "quick connect" which was used for breaking into the a/c plumbing system without ******* the refrigerant charge. These were never popular and then became "illegal" under the Clean Air Act as they allowed some refrigerant to escape to the atmosphere.

An other idea is that the referenced part is an "add-on" filter which Ford and many other manufacturers used for installation after the Ford/Panasonic "joint venture compressors take a dump (a regular occurance). It is "supposed" to remove metallic particles and "black death" from the condenser outlet but in actuality clog very quickly, become a system restriction, and in my book are totally useless, just a bandaid, and not a very good one. Some designs of this filter can be taken apart and cleaned after clogging but will always leak refrigerant after a service attempt.

One more idea...it may be a "rebuildable" receiver/drier (NOT a rebuildable accumulator), somewhat like the aftermarket unit supplied by Vintage Air in San Antonio, TX for the special interest/street rod market. However, it doesn't sound like the Vintage Air units I'm familiar with.

Can ya post a picture here or email me a jpeg? If I could see the part in question, I can more readily identify what ya got. Also, a long shot of the underhood installation so I can see what kind of set-up ya got.

Whatever ya got, sure sounds like it ain't an IH OEM or aftermarket a/c system component!!! Ya really got my curiosity up now, let's figger it out!