There has been a tremendous volume of material in the forums about converting Fiero to R134. A big chunk of the posted info is incorrect and some is dangerous. Hopefully, this article will help sort some of it out.
Notice! This article is subject to change without notice. I am still reading GM's and other information on this subject. The version posted is the most accurate data I have at any given time. There have been many changes to conversion data over time. New research by the carmakers and others is released regularly. This article will be updated as information dictates.
Warning! Improper handling of refrigerants can cause severe injuries or death. Refrigerants are Oxygen Displacing compounds. DO NOT use them in confined spaces!
Warning! Never assume a system is empty when the compressor won't activate. The system can still contain significant amounts of R12 even when there is no pressure. This remaining refrigerant MUST be removed from the system by licensed persons using approved equipment.
At present, no distributor of MVAC components will warrantee parts unless the system is charged with either R134 or R12, therefore I don't recommend using other refrigerants even if they are on the EPA approved list. The USEPA DOES NOT recognize any of the "drop in" refrigerants that supposedly coexist with remaining R12 in the system. Refrigerant compounds containing Butane, Propane, or other hydrocarbons are illegal in many places.
The Fiero system will accept R134. Some systems will accept it better than others. Just what you need to change depends on the condition of the OE system and a few other things.
I've run R12 and R134... While some vehicles may not perform as well with R134, I don't see any problem with using it in Fiero.
Technically R134 is not as good at cooling as R12 but Fiero is so over refrigerated that this will not matter except maybe in really hot climates. In my car R134 has the car pretty well cooled down by the time I've gone just 2-3 miles. The only time I run the system full is for initial cool down in 100o weather. Most of the time the temperature slider sits in the middle. (My car is black and has a sunroof.)
The biggest part of cooling any car down, Even w/o AC, is dumping the huge slug of hot air from a parked car. I simply pop the sunroof open to do that. The car temperature drops really fast that way.
The Fiero condenser and evaporator are the same size used in much larger vehicles. There's enough capacity for at least a good size 4 door and likely a station wagon.
It's so over cooled that even in hot weather it is difficult to make the V5 compressor run at full stroke. While this makes charging the system a pain, it's great for fuel economy. The compressor load is hardly noticeable. (Yes, I've tried GM's official method to get the thing to run full load.)
While the old A6 compressors are easier to charge, you take the full load every time the clutch slams. I've always hated clutch cycling systems. I'll take the variable compressors any day, even if they are harder to charge.
Basic conversion is "simply" recovering the R12 and dumping in R134. This is what most people do when they install the Interdynamics "conversion kit." Three of the biggest problems with this method are...
I don't recommend basic conversion for any car. Yes, I know, it's cheap. This is a "you get what you pay for" deal. At best I'd say it's 50/50 on getting decent results or having a real mess.
The "Full" conversion, short of replacing everything, is much more reliable than basic. Assuming your compressor is good, the "Do It Yourself" cost is between $100-200. The exact total will depend on where you get the parts. There's quite a variation in price so shop around. (Doesn't include renting a vac pump.)
In a full conversion, oil is drained from the compressor. The ACC/dryer and orifice tube is replaced. (The accumulator dryer unit is only designed to last about 7 years.) It's also a good idea while the system is apart to replace the Schrader Valves and the O-rings in the various fittings. Replacing these parts keeps refrigerant in and water out.
The compressor should be removed and drained of old oil. Measure the oil you get from the compressor. Install the same volume of new PAG or Ester oil into the suction port. Pour the rest of the oil into the new accumulator. (No, I'm not getting into oil type. Every time I turn around one is better than the other. Ester is what NAPA put in their kit. Other kits use may use either.)
The O-rings are a main source of leaks in the system, along with the compressor's shaft seal and bad hoses. This conversion method eliminates all the old O-rings and gives you a chance to really look over the compressor. Make sure that all the compressor switches and the clutch are in good shape. (Old Schrader Valves are also prone to leak. See the notes in AC service.) Now is the time to fix them if they aren't 100%.
Actually, this isn't quite a full conversion. A "real" full conversion includes upgrading the compressor shaft seal or even replacing the compressor. Shaft seal replacement is beyond the skills/tools of most people. However, if the compressor is at all questionable, now is the time to install a replacement.
A "real" full conversion would also replace the rubber hoses. This part isn't as important as once thought. It turns out that during its life, the R12 hose soaks up oil and the oil blocks the R134 from leaking through the walls. Anytime damaged hose is replaced, it needs to be the new "barrier" hose or you will lose R134 right thru the hose.
Warning! R134 operates at higher head pressure than R12. Overcharging can cause compressor failure and/or system rupture. Don't forget to include R134 contained in oil charge or sealer cans when counting charge ounces.
NEVER charge anything into the high side port of a running system!
The desired R134 charge is between 80% and 85% of the original R12 load by weight. Due to minor variations in systems, the best thing to do is charge to 75% and test. Then bump the charge up a tiny bit at a time until it works correctly. DO NOT install more than 90% of the R12 charge by WEIGHT! (The reason I say 75%... If you are doing the basic install then 75% could really be 80% or more of the usable capacity.)
The following table is based on the 40 ounce OE charge in my 87SC. It will give you the amount of R134 to reach a particular percentage of the R12 charge. These numbers are only correct for a "full" conversion and a 6 oz (total) oil load.
Note! GM lists most Fiero at 40 ounces but always check the charge label on the AC housing in the front compartment. There may be undocumented variations. The label is silver and blue with the Harrison logo on it and the location usually makes it difficult to read. (I think some or all 88's may run a lower amount of refrigerant.)
|
OE R12 Charge |
Desired % |
R134 to install |
|
40 oz. |
90 |
36.0 oz. |
|
40 oz. |
85 |
34.0 oz. |
|
40 oz. |
80 |
32.0 oz. |
|
40 oz. |
75 |
30.0 oz. |
|
40 oz. |
70 |
28.0 oz. |
Now lets say you've done the full conversion using the Castrol or NAPA kit, you'd load just under three 12 oz cans of R134 to reach 85% of the original R12.
If on the other hand, you do a full conversion and use the Interdynamics kit. You have to account for the 3-4 ounces of refrigerant in the oil charge. You'd install two whole and at most half of the third R134 can. If you also installed a pressurized sealer, you likely would not need any of the third R134 can.
In either case, you likely end up with some R134 left over. Try to find someone that can use it. Once a can is opened, they rarely keep long before they leak out.
Of coarse this assumes you're not wasting refrigerate with sloppy switching cans etc... Switching small cans can waste 1-3 oz or more every time one can runs out.
Warning! Do not try to unscrew conversion fittings! The R134 fittings have thread locker in them and bond to the R12 fitting after install. Do Not heat the fittings to release them! See the AC service article for details.
NOTE: Some conversion fittings retain the OE Schrader cores while others require removal of the OE core. Make sure you know which ones you are using!
When installing the federally required conversion tag make sure you list which oil you put in the system. PAG and Ester should not be mixed in the system. It is easy to forget later what you used unless it is on this label. The label should be placed in the front compartment near the accumulator dryer where it will easily be seen by future service persons working on the system.
The R134 speed lock connectors MUST be installed on converted R12 systems in the USA and Canada. Each refrigerant has it's own federally standardized connectors. Standardized connectors are required in many NATO countries to prevent cross contamination of the MVAC system. Use the correct connectors for your local standards.
Unlike cheap adaptors supplied in many retrofit kits; Primary Seal fittings have their own valve. You really want to use such a fitting on at least your high side test fitting. The GM R12 high side valve was prone to leaking and the problem only gets worse with R134. The R12 valve is not R134 compatible and people that get away using it for conversions are just lucky and/or waiting for a future leak there.
The primary seal valves are not very expensive and are available at many parts stores. Try your local independent or franchise store if you have trouble getting them thru chains like Pep Boys, Autozone and others.
Depending on the fitting you purchase, you will probably need to remove the OE valve before you install it. On the high side fitting I also recommend a tread sealant like Supercool "Refrigerant Leak Lock with Teflon®" (Part No. 7012) available thru many auto parts stores. The tip of the high side fitting isn't the best sealing surface for the O ring in the new valve.
According to what I've read so far, there is a legal requirement that a new high-pressure cutoff switch that must be added to many systems. This switch shuts off the compressor if the "high side" exceeds safe levels. This is in addition to clutch cycling switches. The switch is intended to prevent system rupture and the release of refrigerant. (There is already a high pressure cutoff on 87-88 4 cyl.)
Most Fiero systems should have this switch. If not then you should add one. The limit switch is not difficult to install and is relatively inexpensive insurance against frying the compressor or blowing apart the system. Most of these use a "vampire tap" or T off the high side test port. You will need the AC wiring diagram for your car to hook it up.
What EPA said and what DOT/NHTSA said IS different.
USEPA allow many kinds of things included hydrocarbons. Refrigerant Application doesn't mater to them. Walk in cooler, central air, or your car, it's up to maker/user of item to decide. Propane, etc, has an R number assign.
BUT
DOT/NHTSA bans anything with hydrocarbons in the mix! NHTSA allows R12 and R134a.
I don't use or recommend alternate refrigerants. I'm sure some of them are performing as claimed but there are many things they don't tell you... Like the fact they are flat illegal in many places and anyone that uses flamable products with Propane or other hydrocarbon components is just asking for potentially lethal problems.
As I said above, most parts makers will void the warrantee of new parts if used with anything other than R12 or R134. They can and do test for this. This is not likely to change anytime soon. The biggest factor for this decision by the parts folks is cost. It simply cost too freaking much money to deal with the issues of 50 different refrigerants.
Then there are the issues of supply and service. Availability of some products is limited and many shops won't service cars with other alternates. (Refrigerant identifiers will tell the shop what is in the system even if you don't. Many AC service machines have one built in.)
The biggest problem is that many alternates are blends. When the system leaks, even a tiny bit a year, the lighter chemicals leak out faster than heavier ones. This alters the blend and total system performance. There is no way to know how the altered blend will perform or what damage it might do.
If a "pure" refrigerant like R12 or R134 leaks down, you can add more and know that the formula is always correct. Once a blend has changed due to leakage you can't restore to its original formula, which means the only way to get back to the original is to replace the entire refrigerant charge. This means a legal AC shop ends up with a bunch of trash refrigerant they must pay to dispose of.
The majority of recovered R12 and R134 is reused or recycled. Waste from other alternates is generally treated like poisoned R12 or R134. (Poisoned means the refrigerant has been contaminated with other refrigerant, hydrocarbons, or by mixing R12 and R134 in a system.) That means the stuff can't be recycled and has to be destroyed under EPA regulations, usually by incineration, which isn't cheap.
Do you have an old gauge set that you don't use very often and want to save? R134 adapter kits are available from a number of sources at about $20-30. The conversion set is not to be removed once it is installed.
Daily use sets should have the hoses replaced to prevent refrigerant release. The new hoses will be the "barrier" type just like the new AC systems.
Copyright 2000,2002 The Ogre’s Fiero Cave, D.W.Lane. All rights reserved. Not for reproduction in any media without written permission.