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Superheat numbers for TXVs Expansion Valves

dtpantera on Fri April 04, 2008 5:08 PM User is offline

Year: 1971
Make: Detomaso
Model: Pantera
Engine Size: 351C
Refrigerant Type: R134a
Ambient Temp: 80
Country of Origin: United States


I am installing a new evaporator with an extra row of AC tubes (for a total of 6 rows) and one less row of heater tubes (now only one row).

There are a couple of different TXV's that will work for my evaporator...

I alerady have a EX-9404C that has a Superheat = 8.

But there is also available these TXV's:

A FOUR SEASONS Part # 38880 - Superheat = 5 (which is supposedly a replacement for a EX-9404C),
A FOUR SEASONS Part # 38881 - Superheat = 8,
And a FOUR SEASONS Part # 38602 - Superheat = 6.3.

Is there any real difference or advantage of one TXV over another one?

Thank you,

TRB on Fri April 04, 2008 6:17 PM User is offlineView users profile

I don't think you will need to change the valve. You really have not made that big of a difference in the overall capacity of the coil.


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dtpantera on Sat April 05, 2008 12:46 PM User is offline

Thank you...

That sort of confirms what I was thinking... that there is probably no observable difference.

I am assuming that for automotive cooling that the higher superheat number is better in order to ensure that the compressor does not see liquid.

Just to satisfy my curiosity, in what case would I use a lower TXV superheat number?

If there were more coils? A larger cabin? A colder output? More BTU capacity?

Thank you,

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