A/C problem has weird cause.

[Dirgle]

Backstory:
I recently purchased a 1992 Supra. Overall it was in really good condition. But the A/C didn't work. The previous owner lived by the ocean where it's cool so he never bothered to get it fixed. He did say that the owner before him(original owner) had a R-134 conversion done on it. The only sitcker I could find said that it was R-12 however it had the Toyota R-134 conversion fittings. :dunno:

The compressor clutch was not activating, so I started with fuses. All of them were good. Next I checked a refrigerant charge. Which it had. So then I broke out the DMM and checked all the switches high, pressure/low pressure, relays, ect. I found a defective temperature switch, which after replacement allowed the compressor clutch to kick on. Great but no cold A/C. So again with the gauges. I found the high side was going really high, and the low side was pulling way down, an indication of a blockage, which I suspected to be in the TXV. On to rock auto to order a new updated one, as recommended in JDMMA70's thread, since the system would be open I also ordered a new receiver. And last, since the system will be open I ordered a parallel flow condenser. I finally got the time to tear into it and found something interesting. The blockage wasn't in the TXV as I previously thought.

It looks like the descant bag broke and was allowed to enter the system. At least I know what the problem was.

 

[jetjock]

Not all that uncommon actually. That said good job on the entire process.

 

[easternguy2005]

damn, flushing sucks. I converted over and my ac is tolerable but if I drive 5 miles on a 100 degree day this is NOT the fast cool system. Flush it well because you need every cooling ton possible. Nice work thare - took me a few mins to orient to the shot...been there bro been there.

 

[Dirgle]

Not all that uncommon actually. That said good job on the entire process.

Thanks JJ, over the years I've really lost patience with just throwing parts at a problem. Especially when a little time spent on the troubleshooting process can narrow down the issue. Granted, this time it still got me, it wasn't exactly the TXV, but I'm sure there are still a few beads in there. While I can say I'm not surprised that the descant issue isn't uncommon, as the number of A/c systems I've seen open is pretty low. It definitely wasn't one of the scenarios I had considered(gelled incompatible oils, black death, other contamination). But now I know.

damn, flushing sucks. I converted over and my ac is tolerable but if I drive 5 miles on a 100 degree day this is NOT the fast cool system. Flush it well because you need every cooling ton possible. Nice work thare - took me a few mins to orient to the shot...been there bro been there.

Thanks, believe me this thing will be clean, right down to a nitrogen purge before I start the recharge process.

 

[Dirgle]

Well I can't seems to flush the lines clogged by Silica gel. It has hardened to a point that it will not break up. Unless someone has any ideas for a solvent I'm going to have to head over to the WTB section to try and find some pipes.

Any suggestions would be appreciated.

 

[3p141592654]

Bummer, the standard way to recondition silica-gel is to heat it to about 120-200C, but since its stuck in a pipe I'm not sure that will really help as the moisture will be trapped. New pipes are probably the best path forward.

Since its a form of silicon dioxide, you could probably dissolve it out with HF acid! HF is rather nasty,and not easy to get as a consumer.

 

[Dirgle]

Hmm. I don't suppose your over the counter variety glass etching cream has a high enough concentration of HF acid to do much. That sounds like a mess waiting to happen. If I don't get any bites on the used market by tuesday, Champion may be getting a call from me.

 

[3p141592654]

Throw one in the oven at 250F for 4 hours and see what happens. Just don't use your SO's cake pans! :icon_bigg

 

[Dirgle]

So long as the flash point of the oil they used to charge the system is high enough I might just be able to get away with it.

 

[jetjock]

HF. Man, does that bring back memories.

 

[3p141592654]

Like when a student spilled HF in the lab at grad school. Quite a response from the Haz mat team!

 

[jetjock]

I once built a polypro HF spray cabinet for washing SiO2 from PECVD quartzware. Was a tricky thing to design. Pneumatically powered, teflon pumps, plumbing and valving, auto locking doors, automatic rinsing after AC power loss/PLC fail, nested hardware and software interlocks galore, on an on. The operators were still deathly afraid of it. Worked great though.

Silane, arsine, phosphine, chlorine, solvents, high voltage, radiation, etc. You can have it. Much simpler to worry about smokin' holes

 

[3p141592654]

smokin' hole?

 

[Nick M]

Other blockage was not uncommon in days past, or more current from some. Those old GM round compressors would cast their withers with some regular frequency.

 

[te72]

Like when a student spilled HF in the lab at grad school. Quite a response from the Haz mat team!

I once built a polypro HF spray cabinet for washing SiO2 from PECVD quartzware. Was a tricky thing to design. Pneumatically powered, teflon pumps, plumbing and valving, auto locking doors, automatic rinsing after AC power loss/PLC fail, nested hardware and software interlocks galore, on an on. The operators were still deathly afraid of it. Worked great though.

Silane, arsine, phosphine, chlorine, solvents, high voltage, radiation, etc. You can have it. Much simpler to worry about smokin' holes

Not going to lie, you guys make college sound like it would have been fun if I went into the right school.

I'm also curious what you mean by smokin' holes JJ...

 

[jetjock]

The danger I face in my current profession versus the old one.

 

[3p141592654]

okay, I think I get it now.... a smoking hole in the ground