Odd humming/groaning from ac evaporator

SuperDave

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I have completely redone my ac system on my idi swapped '88 bronco, new compressor, condenser, evaporator, dryer, variable orfice tube and all 3 hoses. The ac cools great and everything works like it should but it randomly makes this moaning noise coming from the evaporator that I can't seem to figure out. At first I thought it was a bushing in the blower motor that had worn out so I replaced the blower motor with a new one and that didn't change a thing, it makes the noise even with the blower off. I don't know if I got a bad part somewhere or if I did something wrong but i got to figure it out and any help would be appreciated.

*Edit* so you don't have to ask the pressures on my snap on manifold gauges reads 30-35 on the low side and 175-200 on the high side. Also it was vacuumed down for over an hour before being charged and I charged it by pressures because I didn't have my refrigerant scale with me.
 

SuperDave

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That's kinda what I thought too and the only reason I bought the variable tube was because I had no idea which color orfice tube went in it originally. My choices were red, blue, and variable which is black. Orfice tubes are not particularly expensive I guess I can try the red and blue ones and see what happens then. Honestly unless someone tells me different I will probably leave it be for now
 

CDX825

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That's kinda what I thought too and the only reason I bought the variable tube was because I had no idea which color orfice tube went in it originally. My choices were red, blue, and variable which is black. Orfice tubes are not particularly expensive I guess I can try the red and blue ones and see what happens then. Honestly unless someone tells me different I will probably leave it be for now

Blue was the factory for R12. Red was factory for R134a
 

SuperDave

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Blue was the factory for R12. Red was factory for R134a


Wow! I did not know that was the difference, in the electronic catalog it does not differentiate other than color. I bet in the old paper catalog it would have. I have a red orfice tube that came with the compressor for my f350 I may just try it and see what happens. Thanks very much for your help
 

chris142

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Those variable tubes are terrible! We threw a box away as they were always failing. Imo these trucks work best on r134a and the Orange tube.
 

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