I am considering converting my R12 A/C system to R134 while my 87GT is torn apart for other reasons. I know I will need the motor running for the work to be completed, so I have several things to do before I can begin work on the A/C system. It may be worth noting that I had put in some R134 when I first got the car, not knowing at all what the hell I was doing. So I am going to try now to undo what I did, and properly convert the system. So....if the lines aren't totally plugged, and the condenser and evaporator can be successfully flushed. What items will I need?
Accumulator (Receiver/Dryer) Orifice Tube R134 Low side fitting for new accumulator (does this part come with a new valve, or should I also get a set of valves??)
I also assume I will need a new high-pressure switch to mount on the accumulator, but I have heard that it needs to be rated for R134, and not the R12 that was originally in the system. Where do I get this switch? How can I make sure it will work with the wire harness, and the fitting on the accumulator?
And lastly, I assume that every part the exposes an O-ring or seal, will need to a new O-ring or seal. Should I get the kit from the Fiero store, or is there a better way to get all the seals and fittings, less expensively? How can I make sure if I don't get them from the Fiero Store, that they will fit and I will get the ones I need?
Am I missing anything?
Thanks!
[This message has been edited by computer_engineer (edited 07-15-2018).]
In so many discussions about conversions, it's been stated that the amount of R134a required is 80% of the capacity indicted for R12. I have just had my compressor replaced (system already coverted) and the paperwork that came with the Four Seasons compressor states that 90% is the requirement for R134a. This works out to 36 oz or 3 12 oz cans for the Fiero.
At the same time, I've been on the sideline of another compressor replacement. Also a Four Seaasons. The difference is that mine was rebuilt from AutoZone and the other was a new compressor from Advance or NAPA. The paperwork with my compressor said that PAG 150 was the oil to be used with R134a, but surprisingly, the new compressor from another vendor didn't specify. The installer called Four Seasons to get the information and they said that Pag 150 was correct. We found contradicting information on another site that said PAG 46 was the correct oil and another said Ester Oil should be used. So, if it's not clearly stated which oil to use, contact the manufacturer or rebuilder of the compressor.
In the link provided by Spadesluck, there are 3 orifice tubes. My experience with the variable, which looked like the one in the center and cost $19.99 at AutoZone, wasn't good. It went too far into the housing and couldn't be pulled out. It had to be pried out, thus destroying it. We went back with the standard orifice tube and it's working just great. RWDPLZ provided much technical information on our projects. Thanks, RWDPLZ.
After performing the 134 conversion on my 84 Sunbird and Fiero as well as my 86 Sunbird and Fiero I can tell you that if you want the best successful conversion pull all the lines loose and flush each section separately. Flush the condenser and evap top to bottom, the oil will flush out first. I put new compressors on due to the failure rate on rebuilds. I found that the original orifice tube works fine and holds up better that the variable. New dryers and pull the R12 valves from the fittings and replace with good quality adapters with valves in them and don't overtighten. I used the PAG 150 as I had completely flushed my system. Use the part number chart available on the forum to get the right O-rings. The kits are incomplete and generic or just wrong sizes. If your switches in your compressor remove ok then use them. (I bought mine at Napa, the cheap aluminum ones at Autozone are junk.)Same with the dryer. If not then you will need to replace with updated versions with added ground wires. From experience I can tell you that using the originals and orifice cools great and I am in Tennessee where it has been in the 90s with high humidity. It is a great update that has worked very well for me. It is a bit of a pain, but going forward you are working with an updated system. Be sure you get the 8 ozs. of oil in the system and the 80% number on the Freon works as it should.
Wow! That is a lot of parts. Not sure which ones I will need, but I am going to be pulling the lines and flushing them one at a time. I already have the compressor off, so I can make sure all the old oil is drained from it. Once I get the car back on all fours, I can pull the condenser and flush it. Is it much of a challenge to pull the evaporator?
Don't need to pull evap and condenser. Pull the lines and use a piece of heater hose to exhaust the flush away from the car. Flush from the line in at the top and exhaust from the lower.
Don't need to pull evap and condenser. Pull the lines and use a piece of heater hose to exhaust the flush away from the car. Flush from the line in at the top and exhaust from the lower.
That is good news...take every bit I can get.
I am ordering a flush kit from Amazon. Fortunately, my father-in-law has a vacuum pump and a plenty of flush chemical, so the only other items I will need are the lower cost variety (o-rings, PAG oil, R134, orifice tube, accumulator). I might order the switch on the accumulator, just to make things easier. I don't think I will bother with the switches on the compressor. According to what I have heard, they don't go bad that often, and their failure usually doesn't mean that the system will not function, just no safe-guards for the compressor.
[This message has been edited by computer_engineer (edited 07-15-2018).]
The red one is the high pressure cut-off. You can test both by checking for continuity between the center tip and the metal outer shell (should see continuity, not open)
The ones here should be replaced, they're not in good shape.
The project I'm in the sidelines on had problems getting the pressure switches out of the old compressor and broke them. They had to purchase the new 2 wire style switches. We're assuming that these are simply pass-through switches with either wire being grounded to the engine. Is this correct? If not, how are they wired into a single wire system?
Does it matter which port the switch is installed in? I understand that they must be connected to the proper harness, but aren't the two switches sensing a common chamber in the compressor?
Not trying to hijack the thread, but to help to add information to it.
The project I'm in the sidelines on had problems getting the pressure switches out of the old compressor and broke them. They had to purchase the new 2 wire style switches. We're assuming that these are simply pass-through switches with either wire being grounded to the engine. Is this correct? If not, how are they wired into a single wire system?
Yes, the originals ground through the compressor body. Most people hook the two new wires to a ring terminal and use one of the compressor mounting bolts as a ground on the compressor.
quote
Originally posted by fierofool:
Does it matter which port the switch is installed in? I understand that they must be connected to the proper harness, but aren't the two switches sensing a common chamber in the compressor?
They can go in either hole, same chamber in the compressor.
If you look closely at the inner ring here, you can see two holes drilled into the casting. These go to the other side, where the pressure switches are.
The red one is the high pressure cut-off. You can test both by checking for continuity between the center tip and the metal outer shell (should see continuity, not open)
The ones here should be replaced, they're not in good shape.
Do you have any photos of the switches mounted into the compressor? So I can have some idea how they are supposed to come out.
Is the clutch cycling switch the thing that is sticking out of the side of the accumulator? I have to assume that it is, since the refrigerant lines and low side service port take up the other connections.
[This message has been edited by computer_engineer (edited 07-18-2018).]
Is the clutch cycling switch the thing that is sticking out of the side of the accumulator? I have to assume that it is, since the refrigerant lines and low side service port take up the other connections.
Yes. It should kick off at 25psi for R-12, and 21psi for R-134, there's an adjustment screw between the terminals, or you can buy one pre-adjusted.
That thing hanging down with the blue and green wires is the electrical connector for it.
Yeah - I had disconnected it looking around it for what needed to be done to remove the accumulator. Just hadn't reconnected it before taking the picture.
the material, is it made out of steel or aluminum? The reason I ask, is I want to make sure I take proper care loosening the refrigerant connectors so I don't strip them. Something tells me that finding replacement lines may prove difficult.
[This message has been edited by computer_engineer (edited 07-19-2018).]
Is the large black nut on the refrigerant line coming into the accumulator a cover for a nut underneath, or this part of the hose or something? Is it metal, plastic or composite or something???
the material, is it made out of steel or aluminum? The reason I ask, is I want to make sure I take proper care loosening the refrigerant connectors so I don't strip them. Something tells me that finding replacement lines may prove difficult.
Those are all aluminum. It doesn't take much torque, because the o-rings do the actual sealing. Finding the lines that run under the car is a PITA, I had to drive 4 hours down state and another 4 hours back with a new set (originals were cracked below the front compartment)
Is the large black nut on the refrigerant line coming into the accumulator a cover for a nut underneath, or this part of the hose or something? Is it metal, plastic or composite or something???
it is quite different from the other connection.
It's not a cover, it IS the nut, that one is plastic. Some are metal on later cars.
What is the canister shaped item on the compressor hose? When I go to blow that hose out, do I have to be careful with that side? Is there anything inside that canister?
[This message has been edited by computer_engineer (edited 07-20-2018).]
What is the canister shaped item on the compressor hose? When I go to blow that hose out, do I have to be careful with that side? Is there anything inside that canister?
On my compressor, which I think is a HR6 (it's on a late 87 GT 5 speed), I have a white collar switch and a red collared one. You told me the red one was the high pressure switch, is the white one a low pressure switch. The web page with all the part numbers lists this as the "Fan Switch". Are they the same thing?
On my compressor, which I think is a HR6 (it's on a late 87 GT 5 speed), I have a white collar switch and a red collared one. You told me the red one was the high pressure switch, is the white one a low pressure switch. The web page with all the part numbers lists this as the "Fan Switch". Are they the same thing?
Yes, the white mushroom switch kicks on the radiator fan at a lower pressure. The fan should run anytime the AC is on anyway. It uses the same fan switch connector as the radiator fan switch on the V6 cars. The switch will close at ~280psi
What kind of oil should I get once the old stuff is flushed out and I get ready to put in R-134a into the system? I know it is PAG, but what about PAG 150???
With much helpful guidance from RDPLZ, I just had my compressor replaced. The first new compressor came with an 8 oz bottle of oil, but it was unmarked and there was no information with the compressor about what weight or even what type oil it was. I had to return it because it had the wrong pulley. I next purchased a 4 Seasons reman compressor. Literature in it stated that PAG 150 should be used when converting to R134a.
Something that should be noted is that AutoZone had 2 HR6 compressors. One was listed as being compatible with R12 while the one I purchased stated it was for R12 or R134a. I suppose that's because of the parts used inside. Ester oil was recommended for the R12 compressor.
For R-12, should use 525 viscosity mineral oil. Ester oil is used for R-134A conversions where you can't remove all of the mineral oil, because of issues with mineral oil and PAG mixing. Some people swear by it, but no manufacturers use it. If the system is flushed and mostly clean, PAG works fine.
From GM TSB #33-12-26
quote
RESIDUAL MINERAL OIL
"THE CONCERN THAT MINERAL OIL IS CHEMICALLY INCOMPATIBLE WITH R-134A AND/OR PAG LUBRICANT HAS BEEN PROVEN TO BE UNTRUE. A NORMAL CHARGE OF MINERAL OIL LEFT IN THE A/C SYSTEM AFTER A RETROFIT TO R-134A WILL NOT DAMAGE THE SYSTEM. MINERAL OIL, HOWEVER, DOES NOT MIX WELL WITH R- 134A, AND WILL NOT PROVIDE ADEQUATE LUBRICATION. TESTS ON BOTH THE ORIFICE TUBE AND TXV SYSTEMS SHOW THAT THE MINERAL OIL PARKS IN PLACES SUCH AS THE ACCUMULATOR, AND DOES NOT APPRECIABLY AFFECT PERFORMANCE OR DAMAGE THE SYSTEM."
The difference between PAG46, PAG100, and PAG150 is viscosity. Think of it as 5W30, 10W30, and 10W40. What you should use depends on the compressor. If you buy a new or reman compressor, check the documentation or ask the manufacturer. They usually come with oil in them already, so you don't want to mix types. Some new compressors have tighter tolerances, and will use PAG46 instead of PAG150. For remans or rebuilding/resealing old HR6 compressors yourself, PAG150 works well.
On my R-134a conversions I have always used Ester oil. It has always worked well without issues. I would only use PAG in a completely clean system or one that originally used it..
------------------ " 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, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, 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 "
On my R-134a conversions I have always used Ester oil. It has always worked well without issues. I would only use PAG in a completely clean system or one that originally used it..
What if R-134a was added to an R-12 system? This is what happened to me when I first got the car years ago (stupid is an understatement). The A/C came back to life and made cool air for 2 - 3 years, but after that, not so much. Last time I took a look at it and connected my gauges, there was too much pressure, like it was clogged at the dryer. I hit the low side valve and some of the oil came out - it as blackish in color. I assume this is from the PAG in the R-134a re-charge bottle (if that is what was in there - I dunno), and the mineral oil, mixing in the system. I need to flush that stuff out of there, and then put in some oil that is compatible with R-134a. There is no guarantee that I will get all of the mineral oil or PAG out, so what is the best oil to use in a situation like this?
[This message has been edited by computer_engineer (edited 07-23-2018).]
On my R-134a conversions I have always used Ester oil. It has always worked well without issues. I would only use PAG in a completely clean system or one that originally used it..
From what I have heard Ester is the one that plays well with other oils.
Thinking of replacing my perfectly good working DA6 compressor with an HR6 remanufactured or other new compressor. Does anyone have a line on where to get a low cost remanufactured HR6, or know of a new one that is a "drop-in" replacement?
[This message has been edited by computer_engineer (edited 07-24-2018).]
Thinking of replacing my perfectly good working DA6 compressor with an HR6 remanufactured or other new compressor. Does anyone have a line on where to get a low cost remanufactured HR6, or know of a new one that is a "drop-in" replacement?
Four Seasons part number 58255 would be my top pick. Autozone seems to have the best price @ $218, rest seem to be around $235
