Danny B

Last year I had my 84 US AC Charged. It has never worked since I got the car a couple of years ago.

When the shop charged it, they also updated it to take 134. It worked for about a week, and they had mentioned that it might not last long due to the cars age.

This week I was looking at the AC with a guy from work whose familiar with AC. As soon as we took off the caps to both the high and low side, they both hissed and he told me I needed Schrader valves.

Is the Schrader valves something I have to go to the 928 Sites to buy or are they generic where I can go to Auto zone get replacements?

Any tips appreciated..

thanks
-Dan

Bilal928S4

Yes, they are generic and you can buy them at Autozone.

WallyP

The Schrader valves are intended to hold the refrigerant only between the time that you take the hose off and the time that you put the sealing cap on...

That isn't where you are losing the refrigerant. Your shop did a very poor job - any decent professional shop should check for leaks both before and after charging the system.

The only way that you will get anywhere near acceptable performance is to find and fix the leaks.

dprantl

And how exactly did they convert to R134a? If they just charged the new refrigerant without changing anything, you bet it's not going to last, not because of the BS that it's an old car either.

Dan
'91 928GT S/C 475hp/460lb.ft

Danny B

They changed the fittings, and charged it...
Then billed me 250 if I remember correctly.

dprantl

Sorry, but it's A/C shops like this that really give A/C a bad name (not to mention R134a conversions). $15 worth of refrigerant and $10 worth in fittings and 1 hour of their time max, and they charged you $250 knowing you will be back, blaming the age of the car that the recharge will not hold. Simply put, they ripped you off.

Dan
'91 928GT S/C 475hp/460lb.ft

Danny B

I figured as much..

So moving along.. I decided I had nothing to lose, so I evacuated teh system and changed out the valves on both High and low side, then shoved a couple of cans in. I don't appear to have any leaks now. I have about 200 on the meter on the high side. Anyone know what It should be?

Also, when I look at the firewall, I can see where the High/low side pipes meet at the expansion valve It's all nice in frosty and my compressor appears to be working.

What's supposed to happed after the expansion valve?

Thanks
-Dan

Danny B

Just an update..

I swapped out my Vacuum heater valve (mentioned as a possibility somewhere else ). Because I got air into the system, I ended up bring it in for a evac and charge ( at a different shop ). No leaks, but it' still doesn't blow cold.


Anybody have any other ideas to try?
Be great if it was something stupid like a relay, like it normally is..

Also, my evaporator fan works, but I never see or hear it come on. I connected 12v to it and it works though..

thanks
-Dan

jleidel

Did you swap the oil in the compressor for PAGG? I bought a bottle today for ~$8.

Danny B

No I didn't. I'll have to research it.. thanks

Fsharp9

The schrader on the low side wouldn't come out, Had NAPA guy look up for my 84 and he said it looks like the whole hose assembly gets replaced. That was not an option for me so I replaced the cap with a new one.......tightly, according to the PO it was converted to 134a in 2007 and the schrader had a slight hiss, its still cold in 2013 so I guess the cap holds the pressure well.

dr bob

[Using my best Cliff Claven tone...]

It's a little-known fact that the seals under the Schraeder valves are sensitive to oil type just as the 0-ring connection seals on hoses and fittings. On my car, there is a total of four Schraeder valves that got replaced. The easy ones are at two the charge ports, The other two live under the pressure safety switch and the pressure transducer, respectively.

When I did the conversion so many years ago now, I failed to remove the existing Schraeder valves before installing the adapters. Very shortly I replaced those charge-port adapters, only after removing the existing Schraeder valves completely. While it appeared that there was a pin in the adapter that would depress the exiting valve, instead it actually bent the valve pin itself and made it just a little bit of a chore to get out.

alabbasi

Ester oil is compatible with R12 and R134. This is what should be used for conversion and will save you from having to flush the system if you want to go back. Almost all of the R134 conversion kits with the oil mixed in use ester oil.

WallyP

alabbasi is correct - POE (ester) is the correct oil for a system that has been converted from R-12 to R-134a. PAG is the correct oil for a system that is R-134a from the factory, or one that has been completely flushed (rare).

Danny B

I was wondering if there's a rats nest around the evaporator .
Is there an easy way to check without pulling it apart?