The car is a 1971 Ford with factory air that was converted to 134 after evacuating the system and adding proper oil. No cold stuff comes out of the vents. Gauges reveal that the low side pressure goes to zero/vacuum when the compressor is turning. The expansion valve, which was swapped out for a proper 134 valve, gets cold on the low side of it (frosty), but the low pressure hose fittings don't.
Is my evaporator core berkeleyed? Can it be unberkeleyed? Thanks in advance for the advice.
I wouldn't discount a bad expansion valve. To be honest, I've never changed one in an R-134a conversion because the temperature/pressure slope is so similar in the parts relevant to air conditioning that the difference doesn't matter.
Sounds more like an expansion valve closed too far/not opening. You can try smacking it a bit with the handle of a screwdriver for fun and see if the readings change but it already sounds like a smoking gun to me.
I have had several short lived expansion valves recently. One was stuck closed out of the box. Another (currently in my Volvo) works OK if you push the high side pressure over 220 psi by over charging it. Low side then comes up from vacuum to 18-24 and fluctuates there. Regardless of brand they all come from china.
Wait a minute: you're saying that I can use the original R-12 expansion valve on the 134 system without penalty? Cuz I bet the 50 year old Ford piece is better.
So long as there is no detritus in it the chance of your original valve working is at least as good as the chance of a new one working. While you are there, why not change refrigerant over to Envirosafe ISO butane? It works better than R12, so lots better than 134, is compatible with either lubricant, any seal, and is a larger molecule than 134, also non hydroscopic. Runs best with slightly lower high side pressure if you have a working expansion valve.
TurnerX19 said:While you are there, why not change refrigerant over to Envirosafe ISO butane?
I've heard lots said about flammability concerns when using propane or butane as a refrigerant. Thoughts?
In reply to snailmont5oh :
Yes, it's flammable, but only a little moreso than R12 or R134a, thanks to the entrained oil.
I'm torn on the subject. On the one had, at least the stuff won't kill you from toxicity if it does (very rare event) catastrophically fail into the cabin and manages to ignite. (Chlorine gas, or mustard gas, or... something bad will form. Chlorinated chemical plus combustion is never a good thing if you like breathing)
On the other hand, if I hooked up my A/C machine to a car that has Bob's Mystery Refrigerant in it, and evacuate the system, I now have a 30 pound can of uselessness that I have to send in to a company that specializes in contaminated refrigerant.
I already grit my teeth when I am at a parts store or gas station and walk past the shelves full of refrigerant with stop-leak in it. That stop-leak will destroy a $20k A/C machine. It's hard to find parts store refrigerant that ISN'T infected with that stuff.
I think your cell phone battery is more likely to burn you than a fire caused by your AC system, pretty much regardless of what you put in it.
Is PAG oil compatible with hydrocarbons?
In reply to snailmont5oh :
Yes, any refrigerant oil is compatible with butane. I can't answer for propane. I also clearly mark any car I put butane in so the next guy knows what he has.
So, my buddy sucked the 134 out of the Wagon, and I flushed the evaporator core with some "Power Shot" stuff that he recommended (which smelled like turpentine with D-limonene mixed in. I got an ounce or so of goo out of it. We vacuumed the system for a half hour, and put the 134 back in. It seems to work better. It's not great, but there are a couple of places where the seal between the firewall and the heater box has disintegrated, so that may be causing some warm air to get into the mix.
If you were closer, I'm getting a thermal imaging camera this week, and I am itchin' to use it on things.
If there was a restriction, it will show up plain as day.
What color is the goo? If it's tiny bits of the insides of your rubber hoses (mixed with some oil) i could see how such debris would restrict the inlet of the TXV. This would be similar to the type of goo you sometimes find in the bottom of brake/clutch reservoirs that never had their fluid changed.
Vigo said:What color is the goo? If it's tiny bits of the insides of your rubber hoses (mixed with some oil) i could see how such debris would restrict the inlet of the TXV. This would be similar to the type of goo you sometimes find in the bottom of brake/clutch reservoirs that never had their fluid changed.
It was pretty black 
If it's black it's probably rubber hose stuff. If it doesn't work well enough the way it is right now i'd consider replacing the hoses when you fire the parts cannon at it.
Vigo said:If it's black it's probably rubber hose stuff. If it doesn't work well enough the way it is right now i'd consider replacing the hoses when you fire the parts cannon at it.
But, all the hoses are new! [\whiny]
Maybe it's from the old hoses.
Yeah, if all the hoses are new you should just be able to try to get the majority of the old debris out of the system by flushing and then have it all work more or less properly.
Caveat to this is that flushing evaporators is a pita peeve of mine that i hate doing, and flushing condensers almost always feels pointless because of their design. So yeah, 'just flush it more', not that that's a huge pita with a decent chance of not working or anything. 
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