whether to convert from R12 to R134 - what is needed? (Page 2/2)
theogre MAY 27, 08:15 PM

quote
Originally posted by sledcaddie:
Why is the accumulator a "must"?

OE ones and many aftermarket units are Not compatible w/ R134 and desiccant "bags" can fail then F'ed the whole system.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

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FX MAY 28, 08:54 AM
Thanks Ogre, valuable information. I can get the certification if I decide to go back to R12...And I have 2 good friends in auto repair shops that are certified to use it. They will get it for me...But, as I said, the R134 is adequate, so if it ain't broke, don't fix it...

[This message has been edited by FX (edited 05-28-2020).]

sledcaddie MAY 28, 09:19 AM

quote
Originally posted by theogre:

[QUOTE]Originally posted by sledcaddie:
Why is the accumulator a "must"?

OE ones and many aftermarket units are Not compatible w/ R134 and desiccant "bags" can fail then F'ed the whole system.

[/QUOTE]

So, if you convert to R134, do you have to buy a R134-specific accumulator? Are there different part numbers for such?
theogre MAY 28, 11:40 AM
All good brands like 4 seasons, the Accum/drier are built to take R12 and R134 now. Just easier and cheaper for them to have 1 part takes both.
~ 20 years ago, can easily find NOS units only take R12 in many store inventories and many bought them to fix AC. You might still find on Ebay etc but you not want them.
sledcaddie MAY 28, 07:56 PM
Thanks. Ogre. Good to know.
sledcaddie MAY 28, 07:58 PM
Thanks, Ogre. Good to know.
sledcaddie MAY 29, 03:32 PM
What, if any, is the advantage on using a "variable" orifice?
Dennis LaGrua MAY 29, 04:20 PM

quote
OE ones and many aftermarket units are Not compatible w/ R134 and desiccant "bags" can fail then F'ed the whole system.




Used a standard #33181 Four Seasons R-12 accumulator for my R134a conversion in my 87 GT. It uses the 3800SC GM V7 Compressor. That was 7 years ago and the system is still working great.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 05-29-2020).]

RWDPLZ MAY 29, 05:14 PM

quote
Originally posted by sledcaddie:

What, if any, is the advantage on using a "variable" orifice?



http://www.fiero.nl/forum/Forum2/HTML/000652.html


quote
Originally posted by RWDPLZ:

The more expensive $30 variable ones are made to improve cooling when the car is stopped, like in traffic or just idling. It's meant to more closely mimic the operation of the thermal expansion valve used by most non-GM systems. Standard VS Variable though, nobody seems to agree if it's worth it or not. One thing to consider is it introduces moving parts to what previously was dead simple, introducing a potential failure point.

If you can get good performance from the standard one, I wouldn't bother upgrading. If the standard orifice tube doesn't perform well at idle or in traffic, it may be worth trying to see if conditions improve.



See also

http://www.acsource.com/sma...nceorificetubes.aspx


quote

SMART VOV - High Performance Orifice Tubes

Now your customers can have:

5° - 12°F colder air (at hot idle)
Reduced compressor load and extended compressor life
Improved performance when converting from R-12 to R-134a
Improved city fuel economy & emissions
Improved performance in factory R134a systems

How it works

The Smart VOV (variable orifice valve) uses system pressure and refrigerant flow to move a metering piston relative to a fixed opening in the sleeve. The piston movement is resisted by an attached spring.

When idling at high ambient temperatures, the piston shifts to a smaller metering area similar to a TXV. This compensates for the reduced compressor output and increases the cooling performance. The Smart VOV also has a unique re-open feature which reduces compressor pressure for severe idle conditions.

At highway speeds, the Smart VOV operates on a large orifice. The net result is better performance than a TXV without the complexity or reliability concerns.

Unlike a TXV, which has constantly moving parts and small internal clearances, the Smart VOV is stationary during most operating conditions and has large internal clearances. Its low friction floating design insures smooth operation and extremely long life.