A/C question

[DannyBNH]

My A/C doesn't work (Never has) on my 84US and before I spent the $$$ to try and fix it, is it better to just try to update it to R134?

The PO said the compressor was gone, but he was not technical, he just drove it and had the oil changed once a year.


Thanks
-Dan

[SeanR]

At this point it's not really a big deal going either or. R-134 is getting up there in price. If it were me, I'd stay with R-12. Many say you can't find it but they are lazy.

Important thing is to get the system so it will be sealed. Replace the hoses, compressor, expansion valve, drier and all the seals. Have it properly vacuumed down and tested for leaks and filled up with the proper amount.

If the above is done the right way the first time, it will last another 10 years.

[924CarreraGTP]

I have access to several compressors from several years if you need one.

[djantlive]

924carreragtp - what is the condition and price of the compressors?

[MPDano]

The proper way as to not deplete our Ozone layer is to first have the R12 or whatever evaced. I had mine done at an AC Shop. Once your system is rid of the freon, you can now disassemble and replace parts as needed, Seans list is good, but I didn't need to replace my hoses as they were good. I replaced all the seals especially if you are converting to R134 (I did), replace the Drier and Expansion Valve. You'll need the r134 adapter as well. Get everything nice and snugged up and sealed. I then took mine to the Ac shop and had them evac to remove any moisture from the system and fill it back up with oil/r134. They have the proper equipment and gauges. My S and Euro have both been done this way and both have freezing AC since the service was done.

[kuehl]

You should have no problem keeping a shark cold with R134a, especially in NH.

If you have an original compressor it might be worth the time to open it up,
inspect the bores, piston, wobble plate and reed valves, ya never know, might
must need a seal kit.

New drier, o-rings, ester oil, 2 barrier hoses, R134a or buy a complete kit:

and off ya go to the Green Mountains or 1A to the beach.

[DannyBNH]

So here I am 2 months later and the AC is blowing warm now.
That didn't last long ( about a month ).

I know squat about AC ( and other things)... What can I do myself to get this going again.
Kuehl ( sorry I don't know your name ). You say I should buy some items above. Can you provide more info?

Also.. If anyone can shoot me any links that might be helpful. I'd like to fix this as cheap as I can ( DIY ).

When the AC was checked for leaks and charged, they said they converted the fittings and it's now R134.

Thanks
-Dan

[BoiseShark]

All I can say on the subject is that you cannot mix the two. It will ruin your system. You have to have it evacuated of all traces of 12 before you put in 134. It is one of the only things that you should just go and pay the price to have someone do it. It seems simple...psi and all...but it's tricky

[1982_928]

R12 compressors, and hoses work fine with 134, so no need to change those. R134 doesnt cool worth a damn, so i would stick with r12.

MPDano, R12 doesnt deplete the ozone. Dont let those california wacko's brainwash you.. Hah.

Expansion valves dont go bad, So why change it?

[MPDano]

Originally Posted by 1982_928

R12 compressors, and hoses work fine with 134, so no need to change those. R134 doesnt cool worth a damn, so i would stick with r12.

MPDano, R12 doesnt deplete the ozone. Dont let those california wacko's brainwash you.. Hah.

Expansion valves dont go bad, So why change it?

I didn't replace my expansion valve. My trusted AC Shop did. They are the Pros and if they said it was bad and went through the trouble to cut it off, I trust them that "it was bad."

Not sure how anyone can say that R134 doesn't cool worth a damn, when both my cars run R134 and cool enough that I need to put the blower on it's lowest setting to keep the hairs on my arms from getting frostbite.

[1982_928]

Well, They dont really go bad, but they can stick over time, so that may be why they replaced it. Sorry.

Whenever i put 134 in anything that used r12 i cant get it below 60, whereas it should be blowing low 40's. That's why i say it doesn't cool worth a damn. Just my personal experience.

[19psi]

Originally Posted by 1982_928

R12 compressors, and hoses work fine with 134, so no need to change those. R134 doesnt cool worth a damn, so i would stick with r12.

MPDano, R12 doesnt deplete the ozone. Dont let those california wacko's brainwash you.. Hah.

Expansion valves dont go bad, So why change it?

R12 compressors use a mineral based oil. 134a requires an ester oil. The compressors don't have the proper seals for an azeotropic blend (or 134a) and the same goes for the non barrier hoses used in an R12 system.
The smaller molecules leak out at different rates and you end up with bizarre pressures within a year.

To properly convert, you need to flush out all the mineral oil and fill with proper ester oil. Change all the seals and hoses. And lastly change the metering device whether it's an orifice or TXV. You get 60 degree air when you don't have the proper metering device. To go 100% you should also install a larger condenser.

[1982_928]

No. Ester oil is compatible with both r12 and 134. I have enough r12 systems (And have charged enough for other people) running on 134a to know that the compressors work just fine, and don't leak out. With the non-barrier hose, as long as the system has had R12 in it before, they wont leak. The R12 acts as a seal in them.

Ive never had a problem with the mineral and ester oil mixing. Changing the seals isnt a bad idea, but changing hoses is not necessary. I know that if the orifice/POA/expansion valve are adjusted correctly, they will cool better. I adjusted the expansion valve in my dads 1957 chevy factory air car, and the other day i got 38 out of it with R134.I just don't like tearing down a sealed, non-leaking system to adjust them. Changing the condenser is not necessary either.

[19psi]

Mineral oil will not properly move throughout the system with 134a. Where are you finding R12 systems with ester oil? Like I stated in my earlier post, the mineral oil needs to be flushed out and replaced with ester. Last I checked, a new 928 compressor is $2300 and rebuilt units are around $500.

With the non-barrier hose, as long as the system has had R12 in it before, they wont leak. The R12 acts as a seal in them.

I've been in the industry for 22 years...please enlighten me more on this! What book or class did you glean that information from?

I adjusted the expansion valve in my dads 1957 chevy factory air car, and the other day i got 38 out of it with R134.

Whenever i put 134 in anything that used r12 i cant get it below 60

Which is it?

[1982_928]

Alright, Maybe i shouldnt talk anymore, because you obviously know everything.

I never said anything about using mineral oil with 134.

And as for me saying 134 doesnt cool worth a crap, thats if you havent adjusted anything. For 134 to get cold, the conditions have to be near perfect. R12 is more forgiving.

[DannyBNH]

I was also noticing today that when the car is idling stationary I can feel the air at the vent a little on the cool side, but not enought to cool off the interior.
Also noticed today it seems to drip on the exhaust pipes after I've stopped. Is this normal?


So it worked for a little bit, then stopped. At this point

- It was checked for leaks and none were found.
- It was evacuated and changed to 134.
- It worked for about 6 weeks ( not super cold, but noticable ).

So to get it working, Do I need to replace everything( hoses, compressor, expansion valve, drier) or is there any additional troubleshooting I can do?

Thanks
-Dan

[19psi]

Originally Posted by 1982_928

Alright, Maybe i shouldnt talk anymore, because you obviously know everything.

I never said anything about using mineral oil with 134.

And as for me saying 134 doesnt cool worth a crap, thats if you havent adjusted anything. For 134 to get cold, the conditions have to be near perfect. R12 is more forgiving.

I gave the proper procedures for changing over to 134a. You are the one that came up with 12 being compatible with both oils which was a moot point as 134a (what we're talking about converting to) is NOT compatible with a mineral oil.
If changing over to 134a, why not make the proper adjustment to a TXV or change a less than $10 orifice in order to get the proper cooling?

In order to get the near perfect conditions you speak of, many cars will need the condenser coil changed out to a larger or crossflow design in order to keep the high side pressure down.

It's documented facts, I'm not making any of this up.

[19psi]

Originally Posted by DannyBNH

I was also noticing today that when the car is idling stationary I can feel the air at the vent a little on the cool side, but not enought to cool off the interior.
Also noticed today it seems to drip on the exhaust pipes after I've stopped. Is this normal?


So it worked for a little bit, then stopped. At this point

- It was checked for leaks and none were found.
- It was evacuated and changed to 134.
- It worked for about 6 weeks ( not super cold, but noticable ).

So to get it working, Do I need to replace everything( hoses, compressor, expansion valve, drier) or is there any additional troubleshooting I can do?

Thanks
-Dan

System may be low again and icing up part of the evaporator coil. Did they put a dye in the system? If so they should be able to find a small leak.

At minimum I would flush the system and replace with ester oil, then change all the o-rings. There are 4 o-rings on top of the compressor where each hose manifold bolts to. There are two allen bolts that hold each block down and they tend to be very tight.
I would not replace the compressor. If the front seal is bad there are kits that can be bought for less than $30.
If the system was flat and/or left open, I'd replace the drier.

134a is composed of smaller molecules which will eventually leak through older non barrier hoses but not in 6 weeks.
A replacement blend such as hotshot or freeze 12 is another choice and you won't need to change your oil. Blends do leak out at odd rates but not enough to make a difference in such a short time. If you run low on a blend a year later or longer, you can't just top off. The remainder needs to be removed and a fresh charge put in. I'm currently using a very rare odd blend that's been giving me uncomfortably cold 30 degree air on a 100+ degree day...it was free and I have enough to last a lifetime.

My 928 drips condensate on the exhaust which makes a hissing sound after shutting it down. I need to get under there and see if a hose needs rerouting or if it's just the way the car was designed.