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R12 dryer problem

Posted: Sat Aug 27, 2016 12:37 am
by truone
Hello everyone! New to the forum but have some questions already. Couldn't find answers anywhere so here I am.
I happen to own 1992 Toyota Cynos know as Paseo to the rest of the world. So I am trying to get my A/C to work again. It was fitted with R12 system. I have a source of R12 so I don't plan to retrofit yet. I had my compressor rebuilt, checked the whole system for leaks and vacuumed it. Added mineral oil into the system no problem. Started to fill it with gas, everything was ok up to some point. I charged about 750 grams of gas in total. I used scales. Here's what happened next. Compressor started to cycle on/off. The low side would show pressure drops but high side would stay low. I checked the pipe that goes from the receiver drier to the evaporator and sure it was cold so I thought that the problem was inside the dryer. Removed the dryer, it would let air go both ways no problem. But when I shook it I could hear desiccant beads rattling, so I knew something was off. Sowed the dryer in two halves. It was damaged obviously by too much pressure. I will add pictures later.
So here's the question. Earlier I had to replace outlet piping so it would fit newer dryers as I couldn't locate any R12-era dryers. So I bought a new genuine Toyota R134a dryer and had it installed. Now I wonder could it be so that newer R134a desiccant won't allow R12 gas to travel through? Sorry for a long post, just trying to give as much details as possible.

Thank you for reading. Any input is appreciated.

PS. Sorry for bad English

Re: R12 dryer problem

Posted: Sat Aug 27, 2016 6:01 am
by wptski
All current dryers are compatible with R12 and R134A.

Re: R12 dryer problem

Posted: Sat Aug 27, 2016 6:59 am
by mk378
Make sure you have the flow direction through the receiver-drier correct.

If drier came apart you need to deal with the particles downstream in the TXV and evaporator.

Re: R12 dryer problem

Posted: Sat Aug 27, 2016 10:42 am
by truone
mk378 wrote:Make sure you have the flow direction through the receiver-drier correct.

If drier came apart you need to deal with the particles downstream in the TXV and evaporator.
I will check all downstream parts. I'm 100% sure about correct flow direction. Still the question remains what caused the dryer damage. I will have some pictures tomorrow. Judging by the damage to the internals of the dryer I would say that liquid gas couldn't get through. It looks like it was 99% blocked. Will get back with more details.