The kid's Audi S4 is in the shop so he needs to drive his winter car (the RX) tomorrow. We put the R152 in and got the vent temps to 38. Easy peasy. Then while taking off the high line he lost some pressure. On an emissions compliant People's Republic of Austin turbo, there are a lot of vacuum hoses and harnesses there. Still blows 42 and we're replacing the drier tomorrow when it arrives from Orreillys so we'll 'dust' the engine bay and do it again!

Thanks, Jack. Great stuff.

Jim

 

Cleaned and flushed all AC lines. Blew them out with compressed air. Replaced ALL O-rings,compressor, and condenser. Added the proper amount oil and pulled a vacuume. High side is at zero low side is a -30. Has held for almost 2 hours. Gonna check gages in the morning and hope they havent leaked down. Will fill tomorrow after work. Does anyone know what kinda working pressures I should be achieving? Mike

 

There is no typical pressure-pressures vary with the outside temp, the interior temp, humidity, fan speed etc.

You need 15.8 to 18.2 oz of R152a. The last time I charged I used an electronic mail scale. Installed a full can (10 oz) then switched cans. I set the can on the scale, hit the 'tare' button to attain a zero read out. Then I charged another 7 oz. I expect to lose about an ounce an a half in the hoses on an R12 connected car.

Done.

 

In the absence of a scale, I have developed the following technique to attain a pretty nice charge.

1.) 90* day.
2.) Pull that deep vacuum.
3.)Bleed all three hoses to eliminate all air.
4.)Prop the gas pedal to make the engine run at about 1500rpm.
5.) Set the controls to recirculate, low speed fan, turn on the a/c button.

6.) Charge in the first can, liquid first.
The low pressure switch should start to cut-out at about 20-25psi and cut back on about 40psi. The compressor should cycle on and off at those pressures. Center vent temps should be low to mid 40's. Allow interior of car to cool off.

4.)Advance fan speed to about 1/3. Compressor should no longer cycle.
5.)S-l-o-w-l-y add small amounts of R152 from second can. Add a bit, wait a bit. add a bit, wait a bit. Eventually the low side pressures will start to drop and the compressor should start to cycle again.
7.)Shut off the valves on your gauges and remove the hoses without losing all your charge.
At this point, you should be pretty close.

-Jack

 

Dont remember seeing this in any of the previous posts. It's a 2004 Dupont preso to SAE about 134a vs 152a and exceedingly geeky. I expected it to be a "152a is evil" piece but after reading it I dont think it was. Slide 22 was interesting in that it noted that PAG is even more miscible in 152a than it is in 134a suggesting that 152a in PAG cars is a-ok. Shouldn't be any PAG in an FC but you never know.

This YouTube is interesting when he does a flammability test with the R152a and a MAPP torch at about 2:30.

 

Swapping the drier with a new one after running for 4 days on 152a in 100-105 degree Austin summer heat. Worked beautifully.

I turned the drier over to drain the oil out. I was curious how much of the mineral oil had migrated out of the compressor and into the bottom of the drier. But there wasn't any. It was empty. Is that expected? If the mineral oil isn't as miscible in 152 as it is in 12, I would have thought the compressor would have pumped it all into the drier but no further.

The drier ports are nice and clean so there wasn't any PAG contamination.

I'll put the recommended amount of ester oil in.

 

So, interesting thing today...

After work I threw in our ozone machine, I have been doing this for a few weeks to get that musty smell out of the vents. I let the car run for about 20 minutes with the ozone machine, AC off but the blower full blast on recirculate.

About 10-15 minutes later I hopped in the car and went to go home and the AC compressor kept trying to stall the engine. The first time it nearly died and then the second time same thing. I revved the engine a bit and everything seemed normal other than the AC wasn't cooling the car. I kept driving and turned the AC off and turned it back on and the car wanted to stall again. I turned it back off and then on and revved the engine and everything seemed to be working again. The AC became cold, but not chilly as before.

Question is, did my damn expansion valve get stuck. When I got home I popped the hood and my return line to the compressor was dripping like a sweaty person. The AC had only been on less than 3 minutes.

I'll hop down there and test it again here in a minute. Maybe I heat soaked the valve (it's thermoregulated) I dunno.

Post back up here in a few minutes.

 

Just tested at 1/3 blower speed at 2k rpm and got 45* vent temp...hmmm... no idea.

 

This YouTube might help...

 

You know you want it-Cool Air!

 

It ended up actually being the bearings on the AC compressor. I ended up having to take the belt off of it to stop the howling and screaming. Whenever I get the chance I need to replace the face of the AC compressor but it is low on my list of priorities on the car right now. It was really nice to have cold AC for a while Jack, I appreciate you coming over to help me with that.

 

So that was the issue with the alternator belts too?

Get a used compressor. We'll recharge it again.

 

No, unfortunately.

I am on orielly alternator #3 and orielly alternator #2 left me stranded 3 weeks ago.

 

Thank you very much for the info in this thread. My a/c blows extremely cold, so much that my girlfriend wants to have a fleece throw stashed away in one of my storage bins =)

 

Cool!

 

Guys is there an alternative refrigerant I can just add to my 89 that has R12? It blows cool, but not cold. R12 is way $$ on ebay so hoping there was something that would mix and not cause issues.

 

R-152a, as talked about in this thread.

 

Thanks, just wasnt sure it'd be ok to mix with the R12 currently in the system.

 

If you just need a top off, stay pure R12. If you have a consistent leak and are frequently topping off, then fix the leak before converting to R152a.


Mixing refrigerants can sometimes yield a blend that doesn't perform as well as either pure refrigerant.

 

Jack, considering the current price of R-12, I suggested just topping off with r-152a. R-12 and R-152a aren't going to be oil and water type of thing as R-152a pressure and expansion rates are similar to R-12.

$12 for 6 cans of computer duster or $103 for 3 cans of R-12? ***** worth more than gold...Wish it didnt eat holes in the atmosphere.

 

Jack, help!

I somehow fixed the wailing compressor issue with crude hand tools and beer.

My freaking refrigerant leaked out of the high side schrader valve. It took a LONG time, but my UV light doesn't lie.

I am going to get my hands on some manifold gauges, side can tap, and a vacuum.Here is my issue though. R-12 gauges are exceedingly hard to find and expensive.

Can I just throw the R-134a adaptors on and use an R-134a manifold gauge set to charge it?

 

Y wouldn't you be able to? Its just a fitting, as long as it seals, you'd be fine

 

My only concern is that it seals against the adaptor...different molecular weights and all. I THINK jack did this when we recharged my car last time, but I just want to make sure.

 

What does molecular weight have to do with the fittings?

 

That's what I did when I serviced my system. Should work no problem.