Ready to recharge new AC.

[uniberp]

Couple questions:

1. How much oil goes into a brand new system?

2. How do I pressure test the system without using refrigerant?

 

The new compressor came with 'assembly' oil only.

 

All the new parts are installed: compressor, condensor, drier, evaporator, expansion valve. Lines cleaned, new o-rings, everything just shiny and new.

 

I picked up a couple 12oz. cans of R134a refrigerant and a 3 oz. can of r134a compatible oil. Underhood label says 'Use 19-23 oz refrigerant'.

 

I have a gauge set and venturi vacuum pump/ac compressor. Think I'm all set to get started when I get home tonight.

 

Somewhere available is a Nitrogen/oil test charge kit that can be exhausted to atmosphere. Anyone use one of those?

 

I think I cold just use some oil and air, and let the vacuum run an ahour or more to dry it out afterwards. Hoping that venturi pump works good enough.

 

**********MP note. I will have professional shop evac and charge, after reading posts below. Thanks all. *************

 

mpergielelmhurstil97legato99forester

[idosubaru]

don't know that i'd dump oil and pull a vacuum right away on a new system. it may pull out a fair amount of what you put in. you'd at least need to somehow distribute the oil internally. i'm not very familiar with starting from scratch like you are, so i'll be interested to see what others say. i'd plug around some automotive and a/c sites on the interent. should only take a couple minutes on a serach engine to find what you need, there's a ton of very good information out there with step by step instructions, that's how i figured it out. not that people on here can't help, but an existing, complete, detailed step by step posted on the internet might be more helpful than a few pages of threads here.

 

i know the ones i've read addressed exactly how to do it and how to do it if you're installing a new compressor...for example, how much oil, what kind and how to add it.

[uniberp]

don't know that i'd dump oil and pull a vacuum right away on a new system. it may pull out a fair amount of what you put in. you'd at least need to somehow distribute the oil internally. i'm not very familiar with starting from scratch like you are, so i'll be interested to see what others say. i'd plug around some automotive and a/c sites on the interent. should only take a couple minutes on a serach engine to find what you need, there's a ton of very good information out there with step by step instructions, that's how i figured it out. not that people on here can't help, but an existing, complete, detailed step by step posted on the internet might be more helpful than a few pages of threads here.

 

i know the ones i've read addressed exactly how to do it and how to do it if you're installing a new compressor...for example, how much oil, what kind and how to add it.

 

Been looking....

http://www.tirechanger.com/rti/OilChartCompressor.pdf

This indicates about 8 oz of oil: 1 receiver, 2 condensor, 2 evaporator PLUS ? for compressor, looks about 3.

 

http://www.firstfives.org/faq/AC/ac_charge.html is pretty good. Indicates I may need to get a real vacuum pump. That's ok. I can return the tools.

[nipper]

Easiest way is to pull a vaccum on the system. If you cant pull a vacum you have a leak.

 

You can use N2 and a snifer, or Refridgernat and a sniffer. There is a mix of N2 and Refridgerant made for the purpose of leak testing. 90% of the time the vac alone will be good enough.

 

 

 

You only need the others to trace a leak.

 

A venturi vacume pump wont work. You need a real vac pump to pull down the vac and hold it.

 

Some things you just have to pay a shop to do sometimes.

 

nipper

[uniberp]

Easiest way is to pull a vaccum on the system. If you cant pull a vacum you have a leak.

 

You can use N2 and a snifer, or Refridgernat and a sniffer. There is a mix of N2 and Refridgerant made for the purpose of leak testing. 90% of the time the vac alone will be good enough.

 

You only need the others to trace a leak.

 

A venturi vacume pump wont work. You need a real vac pump to pull down the vac and hold it.

 

Some things you just have to pay a shop to do sometimes.

 

nipper

 

You're right. I will use the gauges to test for pressure leak, but have the shop evac and recharge. I was shopping for tools/stuff on my lunch hour.

 

http://www.aircondition.com/tech/questions/38/Air-Powered-A%7B47%7DC-Vacuum-Pumps

 

Thanks all. I will update.

[idosubaru]

You're right. I will use the gauges to test for pressure leak, but have the shop evac and recharge.

just take it to the shop, don't bother testing it. if it's all new, it's probably not leaking anyway, i'm assuming all the o-rings and schrader valves were replaced as well. and the major point is that they will test it first before charging anyway, so save yourself the time and effort, you're paying for that service no matter what.

 

most of the newer a/c machines are awesome, it's almost mindless. it's completely automated...they hook it up and the machine just starts doing everything automatically....evac, test for leaks, pull a vacuum and ready to charge...without a mechanic even being there. if i paid for all brand new a/c components like you did, i would have a shop do it as well.

[uniberp]

just take it to the shop, don't bother testing it. if it's all new, it's probably not leaking anyway, i'm assuming all the o-rings and schrader valves were replaced as well. and the major point is that they will test it first before charging anyway, so save yourself the time and effort, you're paying for that service no matter what.

 

most of the newer a/c machines are awesome, it's almost mindless. it's completely automated...they hook it up and the machine just starts doing everything automatically....evac, test for leaks, pull a vacuum and ready to charge...without a mechanic even being there. if i paid for all brand new a/c components like you did, i would have a shop do it as well.

All new HNBR o-rings. Everything not quite tightened down yet. The Schrader valve inserts I guess I can leave up the the shop. They shouldn't be too expensive. So far a VERY easy r&r.

[idosubaru]

the a/c parts aren't hard to replace or get to at all, they are typically very easy actually, with the exception of whatever is behind the dash. everything else is really simple actually. funny how a system that's really difficult to work on yourself is one of the easiest to replace parts on.

[uniberp]

the a/c parts aren't hard to replace or get to at all, they are typically very easy actually, with the exception of whatever is behind the dash. everything else is really simple actually. funny how a system that's really difficult to work on yourself is one of the easiest to replace parts on.

On the Legacy the evap is EASY to get at, a handful of screws and it comes off in it's own separate case. (maybe just compared to a Volvo 240 or an S10: nightmares)

 

I hope the Forester is just as easy, if and when the time comes.

 

I'm kind of bummed I can't do it all myself. Man, what they charge to fix systems I could make a mint. And I have to take a bicycle to the shop with me to ride home and back to pick it up. It's through a crappy heavy traffic part of town.

[nipper]

On the Legacy the evap is EASY to get at, a handful of screws and it comes off in it's own separate case. (maybe just compared to a Volvo 240 or an S10: nightmares)

 

I hope the Forester is just as easy, if and when the time comes.

 

I'm kind of bummed I can't do it all myself. Man, what they charge to fix systems I could make a mint. And I have to take a bicycle to the shop with me to ride home and back to pick it up. It's through a crappy heavy traffic part of town.

 

i have an AC license. Trust me ive thought of buying a machine and JUST doing recharges .. very exp machine, but they are amazing in what they do.

 

nipper

[OB99W]

There are other issues that can come up when charging a refurbed A/C system, but as far as evacuating goes, a venturi vacuum pump may be sufficient. You usually need to get to about 29" Hg or somewhat better; an inexpensive unit can get close, possibly close enough for most uses if you sustain the vacuum long enough (the key issue isn't removing air, it's getting the moisture out). See http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92475 ; they claim 28.3" can be achieved. However, note that the compressor requirement is 4.2 CFM. That means a small, inexpensive compressor probably won't be able to deliver enough air to reach the necessary vacuum level. If anyone decides to go this route, make sure you have enough air delivery available, leave the pump running for a good while, and verify by gauge that sufficient vacuum is reached.

[OB99W]

Not that I enjoy butting heads with Nipper...

 

Easiest way is to pull a vaccum on the system. If you cant pull a vacum you have a leak.[...]

 

..., however "necessary but not sufficient" comes to mind. It's true that a system that won't hold vacuum has a leak, but some systems that seem okay with vacuum will leak under pressure. Vacuum can pull certain fittings together, while pressure can force them apart, so pressure testing is still a good idea.