S1 Aircon Re-gas Experience, R12 substitute

Here as promised the actual Doing part:

As I started this this job I had absolutely no experience with vehicle AC systems but that is now quite different As usual an expensive learning curve! So read on and save money - I hope!

After I received the Freeze12 kit there were absolutly minimal instructions (only on one box). And those instructions on the back of the kit are useless as they are for the professional because I do not posses a vaccuum pump, gauges and a refrigerant recovery system. So it could have been useful to issue just an A4 sheet of instructions for the DIYer. The instructions also didn't refer to the lubrication can and the leak stop can.
I contacted the chap of the shop several times for advice because I ran into trouble occasionally. He in essence said "just squirt the stuff in and it'll work." Well, after my experiences I do not quite agree with him. The whole DIY aircon business is just there to sell components/consumables, only luck will give you a reliably working system because you genrally can't do a proper job without kit and knowledge.

On initial pre-work investigation I discovered that the valves contained in the kit would not fit onto my compressor (SANDEN SD-709 Model 1472). It appears that the F12 kit intentionally uses different types of valves than the standard 1/4" to avoid some dummy using another type of refrigerant. Anyway, to get the gas into the the system I needed at least one valve that fitted. Naively I fitted the new valve on top of the old valve (low side of system (blue)) just to have some sort of adaptor for the filling hose.
It turned out that there was still some residual charge in the system but not enough to allow the compressor to start. That was sort of a good sign so there shouldn't be any "major" leaks.
Anyway that shouldn't be a problem (I was told) as the compressor would start as soon as pressure would build up. I then tried to squirt in bottle No.1. That was leak stop with a tracer charge of refrigerant. As I should have known before, the stuff wouldn't go in as promised. There was just not enough umff in the can to open a valve and I messed about and eventually lost the can of leak stop.

It would also be useful to realise that the pressure in these cans is often near ambient so they won't vent into the system by themselves (especially when the system was not evacuated) or even bypass valves. The content needs to be sucked into the system by a vacuum and the compressor. Also it would be useful to read the instrutions and follow that the leak stop can should be shaken (not stirred) and upside down during the draining process as this is a liquid.

It is almost impossible to judge when a can is empty and they are already very light to begin with. That is true especially for the non-refrigerant can as we will see later.
Anyway, I wasted that can and the dye went all over the place, obviously not into the AC circulation.
Obviously, the stuff would not go past the second valve, only the new (outer) valve was opened by the fill hose. The second valve would of course never open. Realising that too late I had to remove all the pressure in the system (not too much) then removed the insert of the inner Schraeder valve that was in there originally and thus had a nice adapter from old to new. That old valve's seal was damaged anyway. The high side valve in the kit would not fit on my compressor at all although the AC chap said that can't be and he has sold 100s of the kits without problems. (We have heard this before).

Now I went for another try. It is imperative to realise that the hose assy (just as inflating a car tyre at the petrol station) opens the Schraeder valve thus connecting the content of the can straigt to the AC system. The compressor (and ideally an existing vacuum) is then supposed to suck it into circulation. OK, Refrigerant can #1 on and engine on, AC switch on and waiting fo the compressor to turn on. This time upright as we feed the system a gas, not the liquid. The can got a little cold so that is a good sign. But the compressor still would not start. I eventually had enough and pulled off the connector to the pressure switch on the receiver dryer and bridged both connections to start the compressor "manually". That seemed to make some difference and built up some pressure. The can started to freeze and slowly colder than ambient air came from the vents in the cabin. Still no signs of liquid on the window of the receiver/drier. It was difficulat o judge when the can is empty - a trick with the ice formation helped as the hot air from the radiator melted the ice over the vapour zone in the can while it remained frozen in the liquid area. Eventually no liquid was left. It took an eternity to suck this can in, probably 30 minutes or more. I reconnected the pressure switch and finally, there was no need for the manual job anymore.
Too busy to continue so I had to wait another day with can #2. I decided to get the lubricant can in next as that would allow me to retain excess refigerant if that should be necessary. Again here, can upside down although this time not mentioned on the label. That went in without much trouble but took a long time too.
Most of refrigerant can #2 was going in as planned and took its time, the freeze trick again allowed me to judge the liquid level in the can. After some minutes the first signs of boiling refrigerant in the drier window. Making progress... The air out of the vents was getting progressively colder. Again, I had to cut off the charging because of family duties. It seemed to take forever. Unfortunately I was unable to fill the system until there was no sign of boiling refrierant in the window. If I understand A/C systems correctly we should only see the refrigerant in pure liquid form at this place as a solid column of refrigerant should go to the evaporator. That is the place where it should boil off, not earlier in the system. That would make the cooling action begin before the evaporator and we don't want that. So if you have a window on your drier, you should not see any bubbles. That would likely indicate low levels of refrigerant. But other faults are possible.

Yes, Saturday was a hot day and a great opportunity to take out the family and try it out.
It seemd to work great so far although it was obvioulsy not properly filled.
<sweat mode off>
After 20mi on the motorway the cooling action had gradually disappeared. I feared the worst, a leak. After stopping that was confirmed. There was still enough pressure to let the compressor run but there was no A/C action at all. It seemed, judging by traces of oil vapour, that the gas had escaped at the lower dryer connection and all the gas had evaporated nicely into the atmosphere!
<sweat mode on>

Lessons:
Change O-rings
Read the instructions
Think logically
To be sure, weigh cans plus filling hose assy
Use leak stop first and make sure it's in
When there is more than just topping up involved - it is NOT really a DIY job.

1) the dryer should be replaced
2) positive pressure testing with N2 should have been conducted prior to filling
3) proper purging and evacuation should be done. When the system is filled under ambient pressure, the operating pressures and temperatures will not be right. Also moisture in the system may do all sorts of nasties and can totally block the system. It may work OK without for you, but will it last?
4) Only gauges will allow you to read a little more about the status of the system. You normally don't get them with top up kits. A dual gauge is recommended. Still useless if you don't know what to look for.
5) More than elementary knowledge about AC systems is useful even when you give your vehicle to a "professional". As we know, many of these individuhh-als just follow the book and don't understand what they are really doing. That is fine as long as everything goes to plan. It didn't in my case and I expect it won't in yours either, especially if your system is as old as mine. A/C systems are essentially pretty easy to understand but the devil is always in the detail.

I will attempt to recharge the system at some time (hopefully this summer) with ISCEON 49. More value for money. Maybe I can organise a vac pump as well.
If you are in the region and have a similar situation, we can perhaps share the gas.

Michael

My brother is a certified A/C tech, he does have a replacement for R12a - used it OK in an old 911 I used to have. I think its called R21 but could check if you are interested ?

It was a little more expensive than the standard stuff (for which he charges about £50). takes about an hour, vacuum test/pressure test refill with coolant and dye.

he is based in TS12 (saltburn - near middlesborough)

Thanks for the offer but that is a bit too far from here (nr London).


Michael