mystert

Assuming your system is in good working condition and just low on refrigerant from being 20+years old, topping off the system using a set of high/low pressure gauges shouldn't destroy your system. Like Griffiths said, DO NOT use anything with a leak sealer. Also like Griffiths said, DO NOT use the single low pressure gauge that comes on the cans. You really need to monitor the high and low pressures as you add the refrigerant. In my case I had a internally clogged condenser and I could add can after can of refrigerant and the low pressure wouldn't move past 20psi. If I had not had the high pressure gauge to see that pressure go drastically higher than the recommended range, I could have severely damaged my system by overcharging.

rkwfxd

Thank you. A set of High/Low gauges sounds like a good investment anyway as I am sure I will be doing a full R&R of the system sometime in the future.

griffiths

You can try adding refrigerant.
The men in black won't rappel down from a seahawk and take you away.
The FBI won't tap your phone.
Hillary will not be offended.
Al Gore may lecture you while are doing it.
Obama will probably ask to help you.
Trump may sneer at your or allow you to hit from the ladies tees.
But, not matter, you are still on Santa's list.

However, be aware of how what your low and high side pressures are as you are adding the R134a. Best to use 2 gauge (High-Low) manifold.

rkwfxd

LOL thank you.

My future son-in-law is HVAC. He has the gauges but not the adaptors. I'll pick those up and give it a shot.

rkwfxd

OK. I just checked. My AC is empty. Zero pressure at this point.

Do I need to add oil when I add the r134?

Thank you.

griffiths

No. You cannot simply add refrigerant after your latest observation.


Your system most likely contains atmosphere gases (nitrogen, oxygen, argon and carbon dioxide). Revert to my previous post. Properly pull down a vacuum, add 2 oz of refrig oil for good measure (toss some salt over your shoulder while you are at it), then charge and test.

Now the NSA is interested.
Hillary is crushing hard drives.
Al Gore is taking down the solar panels.
Obama canceled on you.
Trump is serving you low shelf vodka.
Santa took out an eraser.

You are totally screwed Dude.

rkwfxd

No I'm not.

Been working on this all morning. Have parts being delivered Saturday.
Still need to pick up a few items after work today (including the oil) but now I have plans to do it right this Fourth of July with a trained and certified professional.

We are going to charge with nitrogen and then use a sniffer to check for leaks. Then put a vacuum on it to get all of that out and then recharge with R134A. Then test it again.

EPA ***** (and Kalifornia is full of them) are welcome to come help and learn how to R&R an automotive A/C system the proper (green) way.

I'm hoping this will get me another year or so out of the system before I replace all the hoses and possibly evaporator and expansion valve..... if I can only find a source for those.

Thank you very much for your advise and input.

Can you please tell Santa to put down the erasure?

A914MAN

Thanks mystert. I was hoping I wouldn't have to remove the (nearly full) fuel tank.

So this weekend my hope is to change/replace:
any O ring I can get to
expansion valve
receiver dryer
compressor oil

Then my friend who does commercial and all kinds of refrigeration work will pull a vacuum and hopefully charge the system

mystert

You should be able to replace all the orings in the system easily. There are two at the compressor, two above the drivers rear wheel, two behind the drivers rocker panel, two at the dryer, two at the condenser, two at the bulkhead fitting behind the dryer, and two on each side of the expansion valve. All very easy to change. I used nylog blue on all
the orings. It's an gasket/thread sealant used for HVAC applications and I recommend it. You can get it on eBay and amazon for under $10

rkwfxd

OK quick update for future information.

My car has previously been converted to R134 and as mentioned above was low (empty) on charge.

I replaced my dryer and then tested the system with an electronic detector. System was tight but the new dryer was leaking at the weld. It was a cheapo ($15) aluminum one from Amazon. Ran down to O'Rileys and bought an expensive ($20) steal one. Noticed that the fittings threaded on much easier with the steal dryer than they did with the aluminum one.

Anyway, after we had everything buttoned up again the only leaks the detector could find was some weeping from one hose under the hood and one hose coming off the condenser. No bubbles but the detector found them. I am told this is fairly common with cars designed for R12 and now running R134.

I am not willing to replace all of my hoses at this time so......

We then purged the system with nitrogen and put a vacuum on it which held well. We had added 2oz of oil when we changed the o-rings. We then recharged it with R134.

On a 85 degree day I was getting vent temps of 53 while stationary in my garage.

Time will tell how often I have to re-charge the system.

griffiths

Not necessarily a leakage issued caused by using R134a.
Rather, you have leaks at those areas.
Just means you'll have to charge the system again some time
down the road.

rkwfxd

Dude! I got the information off of your site.

https://griffiths.com/porsche/air-co...barrier-hoses/

"The average Porsche “shark” 964/993 is over 20 years old. The original factory air conditioning hoses were designed using older technology. This old-fashioned hose line slowly leaks (permeates) refrigerant through its skin overtime. It was common to “top off” or recharge the system on a yearly basis. Today with the high cost of R12 it’s not wise to have leaks of any kind. With the introduction of R134a refrigerant the AC industry determined that the original type hose leaked R134a at a greater rate than R12. To solve the problem a new type of hose was designed that has inner liner which reduces rate of permeation (leakage) of refrigerants through the hose wall. It’s called “barrier” hose."

What am I not understanding or misreading about barrier hoses?

TIA

griffiths

If your electronic leak detector is noting a leak on either a barrier or non barrier hose it is not due to the typical permeation leak rate stated on our site.
Most leak detectors do not pick up the rate leakage the size of 'permeation'. You got a hole or crack in one of your fittings near the hose or the hose itself, or a poor seal at the o-ring.
A 964/993 has only 25% of the amount at best of rubber hose compared to an earlier 911/930; your car has quite a bit of aluminum tubing rather than rubber hose. Your "permeation" rate is much lower.

And yes, R134a does permeate at a higher rate than R12.

"permeation" in terms of the rubber walls without cracks or holes.
"leak" in terms of a crack or hole or poor o-ring seal.

Capice?

rkwfxd

Capice. Thank you.

griffiths

De Nada