How to rinse off UV die on a leaking car a/c system?

Nedavno Duncan Wood napisa:

Even with a small leak? The one such that coolant does not leak for a week or so?

Fairly quickly, yes.

Nedavno Duncan Wood napisa:

Reading this again, condensor should be hot and evaporator cool... Or cold?

Nedavno Duncan Wood napisa:

I guess I'll have to get new condenser evaporator and dryer and start again :-( It is going to be expensive :-(

Get it vacuumed & fix the leak, you shouldn't need to change all of it.

If it's working ,hot & cold.

Nedavno Duncan Wood napisa:

How do you fix a leak at the condenser? I have UV light and goggles, and it shows a leak at the condenser near the connectors for the hose. I think that it can not be repaired, I need to replace it.

I also found traces of the UV die at the drain hoses, so I guess that evaporator is leaking too. I'll check that when I find some time to take evaporator out.

And another leak is the valve on the low side. I changed the needle (the small part that you can undo with the metal cap from a tire valve), but it leaks again. What can I do to stop it? There is a cap that is screwed on there, is that enough, since it's the low side, not much pressure there?

If the O rings and hoses were not changed to R134a compatible items then you would have leaks all over the place. All O rings should be green not black. You may find that some of the leaks will stop with plain r12 in the system. Without a manifold set and a vacuum pump you really are stabbing in the dark at getting it to work at all.

Get a proper valve, not a tyre valve for the leaking fill port, the cap is really only a dust cap

Nedavno Mrcheerful napisa:

I filled the system with R-12 so it can not be a problem. And I plan to get a manifold set before soon.

I did not put a tire valve, it just looks like one. I found a proper valve in the a/c shop. But it is still leaking.

And can condenser leak be repaired?

If it is a copper condenser it could be soldered, but not an aluminium one. in general over here, no-one would bother to try.

Nedavno Yvan napisa:

And it arrived today.

Car was in the garage, ambient temperature 30 deg Celsius (86F). I connected the manifold set, and static pressure was 5.4 bar (78psi).

I switched a/c on, and it started 1.8 bar (26 psi) low side, and 9 bar (130psi) high side. Few minutes later it was 2.2 bar (32psi) low side, and 11 bar (160psi) high side.

BMW factory service manual states I should test pressures at 2000rpm, and at that rpm it was 1.7 bar (25psi) low side, and 12.5 bar (180psi) high side.

I than looked at the sight-glass, and there were some bubbles. So I connected my R-12 bottle and added freon until I reached 2.2 bar (32psi) low side, and 17 bar (245psi) high side (at 2000 rpm).

Service manual has a graph, and for 30 deg Celsius (86F) ambient temperature low side should be 1-2 bar (14.5-29 psi), high side 17-20bar (245-290psi), and temperature out of center nozzle 4.5-8 Celsius (40-46F)

So I was near these pressure tolerances, but temperature was ~15C (59F).

Here are some results:

Engine rpm 2000 (as per factory service manual) Recirculation ON, car in the shade, windows closed

Fan set at 4 (max): Low side 2.3 bar (33psi), hi side 19bar (275psi), temp 15.5C (60F)

Fan set at 1 (low): Low side 2.2 bar (32psi), hi side 17bar (246psi), temp 13.5C (56F)

------------------------

at idle

Fan set at 4 (max): Low side 3.2 bar (46psi), hi side 15.5bar (225psi), temp 15C (59F)

Fan set at 1 (low): Low side 3.0 bar (44psi), hi side 14.5bar (210psi), temp 13C (55F)

After I switched a/c off hi side was constant at 9.5bar (138psi) and low went slowly from 5bar (73psi) up to the same as high side.

I than disconnected manifold set, and drove for a while. Temperature was 12C (54F) minimal with fan on 2. Not low enough.

I did not have appropriate thermometer to measure the temperature at center nozzle, so i measured at the footwell nozzle.

Any ideas what is wrong, why can't I get low enough temperatures?

What's the condensor temperature? I'd suspect the evaporator but it's worth a look a t the condensor airflow.

The gas pressure of the pure refrigerant directly correlates to its temperature, so at 30 degrees (after being left to stand) you should see about 95 psi.

if there is any air in the system you can mess about indefinitely, but try bleeding off (slowly ) a little gas, if you aim for just under 30 psi at

2000 you should have the evaporator at just under freezing point. If you still can't get cold enough air out of the vents then there must still be some air in the system.

Nedavno Duncan Wood napisa:

I do not know, I do not have contact thermometer, but it's hot to touch. What do you think is wrong with the evaporator?

Nedavno Mrcheerful napisa:

We are talking here about static pressure?

Before I added R-12 I had 25 psi at 2000 rpm, but only 180 psi at high side. And outlet temperature was ~15C (60F).

What does the air do?

You need the expansion from very high pressure to low in order to effect a temperature drop. So if it isn't squashed enough in the first place (low gas quantity) it can't burst out of the restrictor and expand thereby drawing in heat. If there is so much (excess gas) gas in there that the low side pressure restricts the gas coming through the (expansion valve) restrictor then the gas can't drop to such a low temperature and take away so much heat (hence the warmer temperature that you have) Hence why I said to bleed a little refrigerant off to lower the temperature at the evaporator.

The static pressure in the system will always be the same (related to ambient temperature), even if there is only a small amount of gas in there. If you check the bottle pressure you will see what I mean.

If there is any air in there, the system cannot work correctly since air does not have the right characteristics of a refrigerant, particularly since it has water vapour in it.

If the system has not been vacuumed out for an hour or so before adding refrigerant then there is little chance of it working right.

Mrcheerful

Nedavno Mrcheerful napisa:

OK. So I'll evacuate the system, take the evaporator out, see if it needs cleaning, flush the system, drain the oil from the compressor, change the dryer, vacuum it out, fill it with correct amount of R-12 (975 gr), and check again.

Do you think that compressor is OK judging by the pressures? I can her slight humming when it engages. How difficult is to change bearing (someone told me that it has only one bearing). Can it be done without disturbing pistons where refrigerant is? Do I need some special tools?

Don't forget to add the right amount of the right oil.

The pressure sound fine. The bearings can usually be changed from the end, I don't have any particular knowledge of changing bearings since it would be normal (over here) just to replace the compressor complete, but you do need a special clutch extractor and a special bearing puller. The compressor will make some noise in any case.

Nedavno Mrcheerful napisa:

I bought 1 liter of a/c mineral oil. I'll ad some UV die too.

a/c shop told me that they can change bearing for =C2=A340, compressors are expensive. Thanks for your help.

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