Air Expansion valve

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Dec 19, 2018
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My Car
2005 Convertible
1973 Mach-1

Like you see from the pic there is some strange connection solution in AC system. Some one previous owners has delete expansion valve from my -73 mustang some reason?? Now there is after market hydraulic connection. Which way I should connect this new Expansion valve. There is one larger connection than other three ones. Should this larger one to be down or up and which way forward or to the fire wall? Do you have any picks? Thank you

Ac connection question.jpg

Expansion 2.jpg

Expansion 3.jpg

Is that larger one connection to low or high pressure in the compressor?

I found some old pictures, but I don't know if they will help you. The expansion valve was next to my fuel pump so that is a busy area of my engine bay. I now have a new A/C system in my car that doesn't have the expansion valve in there.


The large port on the tx valve is for the low pressure return fitting on the pipe to the suction port of the compressor. This fitting is usually at the top and will be facing away from the fire wall. The smaller port under it is for the liquid line from the 'out' side of the receiver drier by the condenser in front of the radiator. The other two fittings on the opposite side are for the evaporator pipes poking out through the fire wall. O'rings have to be fitted at each fitting.  The flow of the a/c is compressor to condenser to receiver drier through tx valve to evaporator returning through tx valve to compressor.

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Thank you both. Now I know how it should be installed. :wrench: