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  #1  
Old 08-04-2011, 12:29 PM
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Some A/C advice needed -- leaking valve stem

I noticed about 3-4 months ago when checking pressures, that after I disconnected my gauges, the valve stem was hissing on the high side. I tried pressing it in thinking maybe some dirt was clogging, but no luck.

Yesterday I got out of the car and heard heavy hissing -- well looks like the high side valve cap blew a hole through it and now my refridgerant is low.

Any ideas on process I should take to try and repair without having to evac or do I not have any options other than evacuation?

And IF I do evacuate, would you recommend I replace R/D for preventative maintenance? I'm not even sure if it was replaced when the car was converted from R12 to R134a. One day when I rebuild system (evap/compressor), I'll backconvert, but I'll keep it simple for right now.

A side note too -- I was seeing over 300psi on high side during hot days (110F)...I was recommended to "soak" condenser coil -- how can I soak it exactly? Or is the cleaner some sort of foam?

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Last edited by ps2cho; 08-04-2011 at 12:40 PM.
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  #2  
Old 08-04-2011, 12:57 PM
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You need a new schrader valve and yes...the system will HAVE to be evacuated before recharging because

#1 you need to get the air out....its non-condensing...and

#2 you NEED to get any moisture out.....

You really are supposed to replace the receiver dryer anytime the system is opened but that means you need new o-rings and need to replace that part of the oil.


However given the small size of the opening you can get the old one out and the new one in quickly enough you might get away with just evacuating and recharging.

Now there is a tool that will allow you to replace the shrader valve insert without losing the charge..if you know any HVAC guys...maybe for a few bucks you could get him to do it for you if they have one of those.

Legally, you have to have a recovery machine to suck the system dry before you do any work or you risk the enviro-nazis from coming over and doing unspeakable things to your nether regions. Because its illegal to vent refrigerant into the atmosphere.
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  #3  
Old 08-04-2011, 01:01 PM
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on a converted car, it's impossible to remove the schrader without first removing the 134 adapters, and they often are locktited in place if you attempt to remove the schrader I recommend first getting heat and warming the adapter well, then gently removing it, THEN get the tool to remove the schrader without dumping the charge...
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #4  
Old 08-04-2011, 01:08 PM
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Gotcha. Sounds like evac is necessary. I'll have a shop recover the leftover refrigerant, i'll go and buy a vacuum pump (I need one to do my 260E soon anyway), replace R/D and both sensors, replace schrader valve then pull vacuum and recharge with correct amount.

Anything else I should do or check with the system open?

Would this pump pull enough vacuum for the job?
http://www.harborfreight.com/automotive-motorcycle/refrigeration/25-cfm-vacuum-pump-98076.html
It says 2.5CFM Pump pulls 75 micron/10 Pascal maximum vacuum.
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  #5  
Old 08-04-2011, 01:11 PM
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Quote:
Originally Posted by vstech View Post
... THEN get the tool to remove the schrader without dumping the charge...
On an already partially discharged R-134a system, the tool will cost more that the refrigerant is worth. And, in some cases, there isn't adequate room to use the tool, especially on the high side valves.
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  #6  
Old 08-04-2011, 01:13 PM
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nah, the 1/4 sae tool is only about 12.00


however, ANY volume of R134 has zero value in one of these cars that's been converted...
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #7  
Old 08-04-2011, 01:23 PM
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Quote:
Originally Posted by vstech View Post
nah, the 1/4 sae tool is only about 12.00


however, ANY volume of R134 has zero value in one of these cars that's been converted...
AH.....BUT the use of the tool will negate the need to evacuate the system as it would not have been opened to the Atmosphere. Saving hours of time with a vacuum pump.
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1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche
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  #8  
Old 08-04-2011, 01:47 PM
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Time is not the issue -- I just want to do it right.
I actually have 2 weeks PTO from work right now
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  #9  
Old 08-04-2011, 07:18 PM
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Question -- (unrelated to 300TE) Do the R12 valve caps not depress the valve stem when screwed on?
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  #10  
Old 08-04-2011, 07:28 PM
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Quote:
Originally Posted by ps2cho View Post
Question -- (unrelated to 300TE) Do the R12 valve caps not depress the valve stem when screwed on?
They should not.
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  #11  
Old 08-04-2011, 07:49 PM
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OK -- just checking.

300TE has been under vacuum for about 1hr, just disconnected fitting and watching to see if there are any drops in vac for 15mins or so, then its time to fill again.

900g for w124 correct aka 32oz of r134a / 3 cans right?
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  #12  
Old 08-04-2011, 07:55 PM
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Quote:
Originally Posted by ps2cho View Post

300TE has been under vacuum for about 1hr, just disconnected fitting and watching to see if there are any drops in vac for 15mins or so, then its time to fill again.
Disconnected the fitting?



Quote:
Originally Posted by ps2cho View Post

900g for w124 correct aka 32oz of r134a / 3 cans right?
The general rule seems to be to use 80-85% of the R-12 capacity when installing R-134a in a R-12 system.
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  #13  
Old 08-04-2011, 07:57 PM
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I meant the gauge adapter sorry.

Also -- should I put 2-3oz of oil in for anything lost during evac?
R12 was 1100g according to specs...
Why does the FSM shows 1000g instead of 1200g -- so 91% less?
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  #14  
Old 08-04-2011, 08:01 PM
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Quote:
Originally Posted by ps2cho View Post

Also -- should I put 2-3oz of oil in for anything lost during evac?
If you replaced the drier. Otherwise, it's just a stab in the dark.
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  #15  
Old 08-04-2011, 08:02 PM
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I'm talking purely from evacuation. I got drier covered.

I guess I'm not sure then? Just for good keeping? I can't think an extra 3oz can hurt...

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