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[Dieseltech67]

John,
Why do you not recommend the FourSeasons 38902 ( upto 105 degrees) or 38904 (105+) variable valve tubes on a diesel Excursions?

[Dieseltech67]

John,
Why do you not recommend Four Seasons 38902 ( up to 105 degrees) and 38904 ( 105+) on diesel Excursions?

[Dieseltech67]

Ok, While waiting on John’s answer as to his non-recommendation on a variable valve tube on front evaporator in a diesel Excursion ( lower engine RPMs than a gasser version) with rear AC that uses an expansion valve on rear evaporator. It is installed in the system now. The system is holding 125psi of nitrogen for over 24hrs.
The plan… Vac down under 500 micron. Watch moisture blips disappear on graph on Fieldpiece’s app Job Link monitoring the Fieldpiece MG44 that is tied into jack on manifold. Close service port valves. Disconnect hose on high side coupler. Attach Fieldpiece MG44 to coupler. Open coupler valves and see if micron spike rise is only a small amount of air in a marriage only rises a bit but then stabilizes snd decay in 10 minutes stays under 1000 micron, Dieseltech67 is golden.
You boys agree??

[JohnHere]

IMHO, a Variable Orifice Valve (VOV) is nothing but a TXV "wanna-be" but is a poor substitute for it. Under certain high-demand circumstances that might overwhelm a VOV, a TXV's needle will open to its maximum flow rate to relieve some high-side pressure and maintain acceptable cooling. A VOV has no provision for thermal feedback, so it can't respond with the precision a TXV does. Therefore, a VOV is a compromise.

Might as well use the OE, standard, inexpensive, fixed orifice tube (OT)—also a compromise—that is designed to provide the proper refrigerant flow for maximum cooling loads. In medium to low cooling loads, excess refrigerant collects in the accumulator to be boiled off with engine heat before the liquid can make it back to the compressor.

[Dieseltech67]

So, I can’t put an expansion valve in there so you still think a fixed tube is better than a variable? Why are diesel excursion guys in TX and AZ loving them. I am lost there.

John, How about plan outlined?

[Dieseltech67]

Just realized that a few days ago, I clicked on page 2 and posted. I did that because this thread shows page 1&2 so I thought the thread had gone to page2.

So, being stuck with 2 options for the front evap that you say are crappy, sans the cost factor, why would I not choose one that is variable?

Maryland gets humidity that you can cut with a knife. You open the rear hatch and barn doors and that big expansion valve instantly is covered with condensation and is dripping water. Ford covered the lines with duct tar. Can I cover the expansion valve body with that stuff if I do not cover the needle’s button plate?? Water back there is a huge issue.
As to boiling off in the accumulator with engine heat, ford put insulation AND a plastic case around it so please clarify your written thinking vs Ford’s. I am trying to understand and learn.