ac system flush and recharge: diy?

[dmma163]

So I found the leak in my 1995 911 ac (a corroded line under the door sill), found the part number, and ordered a new line, as well as drier, and o rings. Assuming I can get the new parts installed, should I try to flush and recharge myself, or take it to a shop. I have a guage manifold and vacuum pump for household ac systems.

[Vmarch]

Unless your system had a catastrophic failure, why flush it? If you do flush it you will need to add more oil. If you still want to flush it, get some AC line flush and the pressurized applicator and do it yourself.

Alternatively, flush it with nitrogen, then run a vacuum to 29 bar, let it sit for at least 2 to 4 hours to see if there are no leaks. You will need gauges set for 134 and the field disconnects plus a can tap or a bottle of 134.

[Hugh R]

If you've got the right fittings for the pump and gauges and know what you're doing go for it. If not, take it to someone. Wear safety glasses and only add to the low pressure side with the can upright. Never open the high side with the can connected, you can blow it up in your hand. Refrigerant can blind you if you get it in your eyes.

[Barrpete]

+1 why flush it?

You can DIY all of the replacement parts and pull the vacuum yourself. That's pretty straightforward. But if you've never charged an AC system before either get some help from someone who has and knows how to do it, or take it to a pro. Like Hugh says, if you don't know what you're doing you can easily hurt yourself.

[dmma163]

Ok, thanks for the advice - we will skip the flush, and go straight to a vacuum test. One question - my guage manifold has the standard female sae 3/8" fittings - what type of adapters do I need to connect to the r134a fittings?

thanks.

[bazar01]

Not sure if you can get conversion fittings for your R22 gauge manifold hose ends, but if you do, the gauges on your manifold set will have a temp scale for R22, R12 and other refrigerants except R134A, but you can read pressures. You can buy R134A hose set for about $40 from Grainger but not sure if it will fit your R22 gauge manifold, it may have a different fitting.
Your best bet will be a gauge manifold set for automotive systems for R134A with quick disconnects and will be around $100 from Grainger.

[dmma163]

My guages have scales for R22, R410, and R134, so I am ok on that. I found these adapters on Amazon, which I think will fit the r134a auto ports:

Amazon.com: Advanced Tool Design Model ATD-3525 Manifold Gauge Set Conversion Adapters: Automotive

I have to wait three weeks to get the replacement line from Germany, but then we will get moving. By then the hot season will be just about over here.

[archtech]

Just did a flush of my A/C system. I was converting from R-12 to R134a, oil wasn't compatible and had a light molasses color to it. Check the condition of the oil... if discolored or smells funny then replace it. As for the lines, you can have them made for like $40 each. I took my old lines in for them to copy on Saturday morning and by lunch time they was ready. Flushing out the system is easy too... put the solvent cleaner in one end and blow it out going the opposite direction. I did this for the condenser and evaporator... blip the air flowing thru... really easy to flush. The compressor wasn't as easy since you have to remove the compressor to drain all the old oil, was still pretty simple. . Fill 'er back up with new oil. My take was that if I had my system open and was replacing parts, this was the time to flush and put new oil to clean the system since the next time may be a decade away. It really doesn't take that much time. As for charging it myself, it was easy as long as you have the gauges... Harbor Freight has them for $30 right now too with coupon! Vaccume pump from them is only $13 too. R134a is pretty cheap. Anyway, for what less than the shops were charging to vaccume and charge the system ($90 not including refrigerant), I got the tools and refrigerant! Oh yeah, if theres and expansion valve replace that too. Good luck with it!

[kuehl]

Remove the expansion valve from the evaporator before you flush the evaporator;
we don't flush expansion valves, driers or compressors.

[dmma163]

Archtech - getting your line custom made sounds like a good idea. I wish I had known about that possibility before I ordered mine (at $230 and 3-5 weeks from Germany). Just for future reference, what sort of shop made the line for you?

thanks.

[rick-l]

If he does not flush (which I for 1 would not) how much oil should he add given the hose leak is at the low point in the system?

Should he add it into his new receiver/dryer?

[scottb]

Originally Posted by dmma163

I have to wait three weeks to get the replacement line from Germany, but then we will get moving. By then the hot season will be just about over here.

Did you order an original Porsche part? If so, why? You can get excellent hoses from Griffiths.com and Rennaire.com, or likely your local shop make up hoses and reuse your existing fittings.

[Hugh R]

I flushed my condensors and evaporator (with expansion valve out), I used denatured alcohol and a bunch of crap came out. Let it air dry in the sun for a day before putting back together.

[dmma163]

Yes, I ordered an original oem porsche part. It is an aluminum line, not a hose. I don't think we have any shops around here that specialize enough in ac to make custom lines.

[T77911S]

i was at the AC store the other day and saw the 134 adapters that screw on to a standard set of hoses.

i bought a seperate set a while back just for doing 134. even though the ones i bought could be used on r12/22 or 134, i opted to just use them on 134/freeze12. i have seperate gages for r12 and r22. another thing, my vac pump has the standard r22/r12 fitting, i had to search 2 cities to find one adapter to convert those funky 134 threads over to fit my vac pump.
i hated to buy gages just for 134, but i am glad i did now. what sucks is some day i will have to buy them for 410. that adapter may be easier to find now.

[archtech]

This is the shop that copied the hoses for me. They made them so quickly!
HOME
Just brought the old hoses in and they copied of them with new hoses and fittings that can take the R134A better than the old stuff... barrier hoses or something. They also had a variety of expansion valves, retrofit adapters, oil, flush solvent, etc..... It's just a little shop, but they look quite busy and gave me a wealth of information and confidence to tackle this myself. Repair shops send their stuff to them too.

[dmma163]

Ok, so I finally got the new oem aluminum ac line, installed it and a new drier, with new o rings and a little bit of Nylog blue at all joints. Unfortunately, it will not hold a vacuum. It must be a fairly substantial leak, since the vacuum will not even pull down below about -5 psi. So what is the best way to locate an ac leak? Or should I give up and take it to a service shop?

[rick-l]

It's R134 right? R134 with green UV dye in it is $11 at Wal-Mart.

If that does not work a new Inficon TEK-Mate leak detector is about $110 on e-bay.

[dmma163]

Thanks, Rick.

Yes, it is R134.

I will look into that stuff.

[kuehl]

Originally Posted by dmma163

Ok, so I finally got the new oem aluminum ac line, installed it and a new drier, with new o rings and a little bit of Nylog blue at all joints. Unfortunately, it will not hold a vacuum. It must be a fairly substantial leak, since the vacuum will not even pull down below about -5 psi. So what is the best way to locate an ac leak? Or should I give up and take it to a service shop?

So now you know that "Nylog" is not a magic bullet. A leak of that magnitude you would be able to almost hear or see. You could add some R134a to the system, use a electronic leak detector however you see how the costs can add up. Try this:
Disconnect the high side line from the compressor and cap off the compressor port. Use 'shop air' or a compressor and pressurize the system through the compressor to deck lid condenser hose; if you can't make a quick jig to hold the air hose onto to ac hose end have a friend handle that part. Get some soap and water and wet every joint or hose connection following the refrigerant loop (deck lid condenser inlet, then outlet, then up to the front condenser, drier, expansion valve, with it watch for bubbles. If you don't find the leak at that end reconnect the high side hose and repeat the process on the low side hose going back to the evaporator. If you don't find
glory in this then go back and systematically open and inspect every connection
following the refrigerant loop. Or, you will have to invest in some equipment as mentioned earlier.