Any hope to refurb this compressed air dryer?

5030 · May 10, 2020

strantor said:
Just realized I didn't answer all your questions. It is R134A from the factory. I wouldn't be changing anything. I don't know about oil though. Should oil be added you think? When a refrigerator system suddenly loses pressure is all the oil blown out?

I doubt this thing takes much refrigerant at all. It's a tiny system, much smaller than an automotive A/C and even smaller than a window unit. I believe it is 400W total for the whole thing.

if it's 134, it takes PAG oil. If it's a sealed refrigerator type compressor, not much, maybe 1/2 ounce. If you pull it down to 30 inches or so, you'll suck the oil out. Not knowing the amount of refrigerant is workable. Just don't fill it above 35psi on the low side.

grsthegreat · May 10, 2020

Hf still sells them. 299 still.

strantor · May 13, 2020

I couldn't let it go. I couldn't go out and buy a HF dryer for $300 until I know for sure this one is toast. So I invested the man-hours to learn all the fittings and particulars of the pressure switch; as I suspected, it is custom ordered by Quincy with hard-to-replicate facets all the way around for no apparent particular reason other than to ensure that you get it from them and pay $300 for it. But ultimately it's just a 150psi pressure switch with a 25psi deadband. On at 150PSI (152 precisely) and off again when it falls to 125PSI (123 precisely). It's a double throw switch and they were using the normally open contact. It has some queer 7/16-20 female interface with a hermaphroditic schrader tickler internally, the likes of which I was unable to find in any other switch under $300. So I crushed what was left of the switch in the vise to harvest the brass interface port and chucked it in the lathe and put 1/4NPT threads on the outside of it. Now I can use nearly any HVAC or well pump or air compressor pressure switch on the market. I opted for this one; $6 ($10.90 for a pair of them, precisely). Its output is reversed from what I need but I'll throw a relay in there to re-release it; I have plenty of relays.

Then the issue of charging it with freon. They used 1/4" SAE flare fittings for both the high and low side. I don't know if this is normal or not but I could not find any manifold gauge hoses or adapters to accommodate this. I did find an automotive R12 conversion kit at Autozone though, which included some adaptors that fit over the SAE fittings and let connect the normal automotive manifold QDs to it. I also had to buy the schrader valve kit because I didn't have the stupid tool to pull the stems.

I charged it up just a little bit with an old mostly empty leftover can of R134a to make sure I had high/low ports correct (the system is a bit confusing) and make sure the compressor would actually compress gas before I spent any more money. So $17 into it and all I need is the $6 pressure switch and a can of freon. Take that, Quincy!