Hey guys, my wifes A/C in her '92 Z has been converted to 134A with one of those cheap kits from Auto Zone or somewhere like that, and to make a long story short, it sucks. It did'nt function at all when we got the car because it had a hole in one of its lines, we got that repaired but rather than having it filled with expensive R12 I converted to 134A. It blows fairly cold when moving but get very luke warm when idling. Its like the compressor is'nt spinning fast enough for the 134 to circulate properly, as soon as you accelerate the a/c's temp starts to drop again, but never really gets cold. I have 134 in my '98 T/A and know it does'nt get as cold as R12 used to but it should do better than this. Does it work any better to have it "professionally" converted over, or does this cheap kit do exactly the same thing? Is there anyway to make it work better for her? She does'nt complain, but I think it sucks, so I want to fix it. Could I put a smaller pulley on the compressor to spool it up? If so, where could I find such a pulley? Would I need a shorter belt? Have any of you guys ran into this prob? Any suggestions would be welcome. Thanks

 

Blk Brd,

Welcome aboard!

The major problem with a retrofitted system is that the evaporator is sized to remove heat with R12, not R134a. The 134 is less efficient (has a lower latent heat capacity) so in the same size coil will not cool as effectively as R12. One thing you can do is clean the evaporator to maximize heat transfer. Almost ten years accumulation of grass clippings, leaves, seeds, dust, and mold might be coating the coil. It can be a time consuming task, but is important if you intend to retain the R143a.

Personally, I wouldn't use the R12. It's far too expensive and will only increase in price. If you are considering changing from R143a, check into MP-39. It is a blended replacement for R12 in systems designed to operate above -10°F. It is considerably less expensive than R12 at just around $6.00 per pound, but you probably won't find it in automotive service centers since auto refrigeration certified technicians are not generally allowed to acquire it. You'll have to find a refrigeration shop that has universally certified technicians who can use the product. Ask about Forane 401-A or Icor "Hot-Shot". They are both MP-39.

It has better latent heat characteristics than even R12 (it cools very well), and operates at a slightly lower pressure, so the system isn't overworked as with R134a. It mixes well with the mineral oils that might be left in some system components, and with any remaining traces of R12. I'm using it in two vehicle systems, and several neighbors have had benefit of it as well.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

The correct conversion requires a larger condenser and a smaller orfice tube due to the thermodynamic properties of R134A. That is why it is colder when you drive, more air through the condenser. The smaller orfice tube will make it run colder, but create more pressure and heat on the high pressure side and make having a larger condenser required. You should not need a different evaporator as long as the system is running cold enough.

------------------
89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

Vader,

I just went to Icor's site, that stuff is awesome! There are some supply houses around here (Johnstone), so I'm thinking of doing up my system for the summer! Thanks for the heads up from all of us!

------------------
-Jason M. 1991 Camaro Z28

 

Vader,

Thanks for the information! I didn't even know a retrofit existed that was better than R134a.

I'm going to do more than just think about changing (hello Jason!) this summer, I'm going to try it!

As the site Vader recommended (Icor International) www.icorinternational.com/ stated, you'll only get about a 20° reduction in temperature using R134a but using Hot-Shot R-414B, you'll get equal to or better performance than R12!

Although I didn't see anything specifically stating that Hot-Shot could not be purchased by the general public at the Icor site, and based upon the description of the recharging procedures, I got the impression that this product was not intended for the the general public (as Vader hinted at). Even if I had some, it looks like some special equipment (vacuum pump and gauges) would be needed to use it. In that regard, R134a would be better.

[This message has been edited by Stuart Moss (edited June 17, 2001).]

 

good points, what does it take to buy it and then what does it take to convert ? I'm very interested in this switch myself. Thanks for the info . . .

 

Stuart,

The product contaons HCFCs (22, 152a, and 124), so you'll probably need to have your cert card to get it. It isn't directly recommended for automotive systems because it can be flammable under pressure so the system can not have any air in it - in other words you'll really need a vacuum pump.

JJ,
Johnstone has it for about $200.00 per 30# cylinder, but the local branches around here are stringent about requiring the certification license number before selling it.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

It's ashame your 92 a/c was not working cause my 92 Z28 vert with 40K will FREEZE you out of the car! I mean it gets cold and this is down here by Key West where it's hot right now.
I just converted my 89 RS to R134 and she seems to be doing okay, no where near as cold as the R12 but doing well. Wish I had know about the other stuff before I did this.

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Thanks for the replies guys! You guys seem very knowledgeable on the subject, I'll re-check out the system with your comments in mind and see what I can do to improve it. Thanks again.

 

Make sure the aux. fan is kicking on when the A/C is turned on.


------------------
ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R
and 2 POS commuters...

R.I.P. #3
"He can see air"

 

I am an A/C universal tech. mostly commercial and industrial but I do know in automotive the one thing you have to worry about with blends is the R22 content. R22 is designed to be used with "hard" piping and brazed fittings. When used with automotive A/C systems the R22 has a tendency to leach out through o-rings and the rubber hoses especially if they are not barrier hoses. This causes the gasses to break down since the "recipe" of the blend must remain the same for the proper cooling effect. If you have a leak you must evacuate the entire charge and recharge. The majority of the ones that do not contain R22 contain hydrocarbons, such as propane, which are flammable. Also there are no such substitutes that are "drop in replacements" all systems should be flushed and pulled into a vacuum to remove moisture and impurities when changing refrigerants. These are some of the reasons why the EPA recommends and many people use R134a.