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Re: 1990 honda retrofitted to R134 , holding pressure, holding vacuum , not cooling
Posted: Mon Jul 18, 2016 11:42 am
by greenquark
Updates:
I have an expansion valve at home, I have been playing with. I noticed there is an allen nut taht you can turn and close/open the flow. Is there any specification to set it right for R134a? Like number of turns from a tightening position?
Cheers
Re: 1990 honda retrofitted to R134 , holding pressure, holding vacuum , not cooling
Posted: Mon Jul 18, 2016 4:44 pm
by mk378
Don't turn it at all. Look on the top of the valve it often says R-134a. In any case, the difference is slight enough that new TXV's are set up to to work with either refrigerant.
The screw changes the temperature-pressure response of the valve not a fixed opening. Adjustment requires operating the valve under pressure in a test rig, which they did in the factory for you.
Re: 1990 honda retrofitted to R134 , holding pressure, holding vacuum , not cooling
Posted: Mon Jul 18, 2016 6:16 pm
by greenquark
Thanks for the info. I took it from an old evaporator. I had no idea whether it work or not. So I was testing it to learn how it really works.
I put the bulb in Water with ice and it didn't close, but I put it in the freezer and it did...I tighten the allen nut a bit and it close a bit when I put the bulb in icy water. I was trail-error until the valve closed at that temperature ( icy water). I thought you could control the performance of the TVx by moving the screw in or out.
By the way , the Tvx came from a 1991 honda...it does not say R134a anywhere. That is why I was asking if you could calibrate by the number of turns.
Re: 1990 honda retrofitted to R134 , holding pressure, holding vacuum , not cooling
Posted: Tue Jul 19, 2016 2:33 pm
by mk378
I wouldn't trust a used TXV. A new one is only about $20 and good to go with R-134a.