Erik N

I had my system apart a few years back, when I did the 4.7 transplant. Put in a new dryer etc, some O-rings and a shot of oil. Did not touch the compressor.

After it was all back together, I pulled a vacuum on it and left it for a couple of days. When I returned, there was little vacuum left. So I never charged the system with R12.

How should I go about finding where the leak is? Is there a dye I can add to find out, without adding R12? I don't have any reclamation equipment.

SeanR

I use nitrogen and pressurize the system, then take a squirt bottle with soapy water and start spraying all the joints. Typically ends up with nice bubbles.

If you don't have access to a set up like that.............I'd go about changing all the seals and re-doing the vacuum again.

Erik N

I like the bubble idea. Stupid question maybe, but could I just use compressed air, assuming the compressor tank was clear of water? Or maybe a 12V compressor- the humidity has been super low lately. I would need to vacuum the system again anyway...

jwillman

I think the issue with compressed air versus nitrogen is that it is not inert or free of water. Regardless of humidty when you compress air you also pack what water there is in the air into a smaller area so you run the risk of ruining the dryer.

Erik N

Yeah I read up on that on the internet. Unless you have a high-quality separator it's a bad idea.
I bought the car with a dead A/C in 2000, I don't know if it would even work with freon in it. Sooo...
Next question: If I were to charge the system w/ nitrogen, everything SHOULD function as it is supposed to, except for the actual cooling of the air, right? As in, I could charge the system, check for leaks and also check to make sure the system even activates, right?

SeanR

I would not turn the system on with anything but Freon in there.

The function of the electronics can be done with an ohm meter and if the compressor clutch clicks, and it spins freely, you should be good to go. If you are worried about the compressor, take it off and have a rebuild shop take a look at it. No harm in that.

Erik N

I have a half a mind to just get the system vacuumed again, and then shoot in a can of freon to see how it goes.
When the vacuum is pulled, it removes the oil as well, right?

nuc

Pulling a vac will will not remove any negligible amount of oil, so go ahead. If you feel up to being a non-greeny pop a can of freon in and then check for leaks. Find, repair then charge to weight.

If you want to be green, do as others said. A local A/C shop should, for a nominal fee, be able to put nitrogen into your system, so that you can find the leak.

If you want to do it the DIY'er way, go to the local HVAC wholesale supply house (Johnstone, etc..) and buy a tank/regulator of nitrogen. Then you can do it yourself and have all your tires filled at the same time. Also, comes in handy when doing repair work to your residential HVAC unit when you are brazing a lineset.

'84 Euro 5 spd.

dprantl

If you try to run the system with N2 inside, you will kill your compressor. Refrigerant carries oil with it that the compressor needs for lubrication. N2 does not do this.

Refrigerant oil is not removed when pulling a system vacuum. You are just removing all air from the system, and at the same time boiling off water and removing that as well. Refrigerant oil leaks out in small amounts when the refrigerant leaks out. The only other way refrigerant oil gets out of the system is if someone drains/flushes it out, or if a component with oil in it is replaced with one that doesn't have any. Too many times people overestimate the amount of oil lost when there is a refrigerant leak and the system ends up being overfilled with oil, lowering heat exchange efficiency on both the evaporator and condenser.

Dan
'91 928GT S/C 475hp/460lb.ft