Fabled R12 to R134a Conversion Chrysler Bulletin

[eaglescout526]

NO: 24-01-95 Rev. A

SUBJECT: R-12 to R-134a A/C Adaptation Service Procedure

DATE: Mar. 3, 1995

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 24-01-95 EFFECTIVE DATE MAR. 3, 1995 WHICH SHOULD BE REMOVED FROM YOUR FILES. THIS IS A COMPLETE REVISION THAT ADDS MODELS, PARTS AND PROCEDURES.

THIS PROCEDURE SHOULD ONLY BE PERFORMED ON VEHICLES TO MAINTAIN AIR CONDITIONING OPERATION WHEN R-12 REFRIGERANT IS NO LONGER AVAILABLE. COOLING PERFORMANCE MAY BE LESS THAN ORIGINAL SYSTEM DEPENDENT ON OPERATING CONDITIONS AND ALSO MAY VARY BETWEEN VEHICLE MODELS.

NOTES:

1. This bulletin excludes (AB) vehicles built after 8/1/93 and (XJ/YJ) vehicles built after 1/1/94. These vehicles are equipped with R-134a refrigerant.
2. 1989-1991 (AD) non-intercooled diesel engine equipped vehicles are not available for adaptation.
3. 1990-1991 (AQ) vehicles equipped with 2.2L engines are not available for adaptation.
4. 1987-1992 (AS) vehicles equipped with 3.0L/3.3L engines and front and rear A/C may exhibit high system pressures and panel outlet temperature variations when operated in high ambients after being adapted to R-134a. These vehicles may require an engine cooling system upgrade package.

DISCUSSION:

This bulletin involves adapting vehicles with R-12 refrigerant A/C systems to operate using R-134a.

NOTE: WHEN SERVICING THE AIR CONDITIONING SYSTEM, FOLLOW ALL CAUTIONS AND WARNINGS AS OUTLINED IN THE APPROPRIATE SERVICE MANUAL

PROCEDURE:

Review Safety Precautions and warnings before proceeding with this procedure. Air temperature of the test area and inside the vehicle must be 70° F (21°C) minimum for this test.

1. INITIAL SYSTEM OPERATION AND PREPARATION

   NOTE: WHEN REPLACING ANY COMPONENTS AND/OR OPENING ANY LINE FITTINGS, NEW R-134a COMPATIBLE SEALS OR O-RINGS MUST BE INSTALLED

   1. Review the Component Chart and installation notes attached to determine the parts required for the particular vehicle being adapted.

       

      Passenger Car	Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7
      Minivan	Figure 8, Figure 9, Figure 10, Figure 11
      Dodge Truck	Figure 12, Figure 13, Figure 14, Figure 15, Figure 16, Figure 17, Figure 18
      Jeep	Figure 19, Figure 20

       

      • R-134a Adaptation Component Chart - Passenger Car
      • Compressor Drive Belt Chart (Figure 21)
      • R-134a Charge Port Adapter Chart (Figure 22)
      • R-134a Adaptation Label P/N 4762869 (Figure 23)
      • R-134a Performance Chart (Figure 24, Figure 25, Figure 26, Figure 27)
   2. If the system is functioning properly, proceed to step A3. If the system is not functioning, determine the cause. If the system has no charge, charge the system to 50 psi with R-12 refrigerant. Identify any leaks and/or failed components. If the system is still not functioning, proceed to Step A4.
   3. Operate the A/C system at engine idle speed for 15 minutes on high blower speed and outside air mode to maximize the oil in the compressor.
   4. Evacuate the system using an approved recycling/recovery station.
   5. Repair or replace any failed components with the exception of the compressor.
2. CONVERSION PROCEDURE

   NOTE: IF THE COMPRESSOR HAS BEEN PREVIOUSLY REPLACED WITH A 709CA OR 709CC SERIES COMPRESSOR, IT WILL NOT HAVE TO BE REPLACED UNLESS IT HAS FAILED. IT CAN BE IDENTIFIED BY THE CASTING NUMBERS "709CA" OR "709CC" LOCATED ADJACENT TO THE SUCTION AND DISCHARGE PORTS.

   NOTE: SPECIAL EFFORT MUST BE USED TO KEEP ALL R-134a SYSTEM COMPONENTS CAPPED TO PREVENT MOISTURE FROM ENTERING THE A/C SYSTEM OIL. MOISTURE IN THE OIL IS VERY DIFFICULT TO REMOVE AND WILL CAUSE A RELIABILITY PROBLEM WITH THE COMPRESSOR.

   NOTE: REMOVE THE SCHRADER VALVE CORE FROM ALL R-12 SERVICE PORTS EXCEPT WHEN USING STRAIGHT R-134a ADAPTERS. FAILING TO DO SO WILL PREVENT THE SYSTEM FROM BEING EVACUATED OF FILLED WITH REFRIGERANT.

   NOTE: CAP OFF ANY REMAINING R-12 PORTS USING SEAL CAP P/N 4773153 (3/8-24 THD) OR P/N 4773154 (7/16-20 THD.).

   NOTE: THE A/C SYSTEM SIGHT IS NOT VALID FOR DETERMINING THE CORRECT R-134a CHARGE LEVEL ON A ADAPTED SYSTEM. THIS IS DUE TO THE RESIDUAL MINERAL OIL LEFT IN THE SYSTEM. IT IS HELD IN SUSPENSION AND DOES NOT MIX WITH R-134a REFRIGERANT. IT WILL APPEAR AS A WHITE "MILKY" STREAM OF REFRIGERANT THROUGH THE SIGHT GLASS.

   NOTE: THE CLEAR MYLAR OVERLAY MUST BE INSTALLED OVER THE NEW LABEL.

   1. Remove the compressor and drain the mineral oil. Inspect oil for any unusual metal content. If a new compressor is a required adaptation part or is being replaced because it is a failed pert, the mineral oil must be drained from the new compressor. In this case it will not be necessary to drain the oil from the old compressor.
   2. With the compressor off the vehicle, refill with new R-134a refrigerant oil in the amount called out in the Adaptation Component Chart.
   3. Remove and discard the filter/drier/accumulator.
   4. Replace the HPRV (High Pressure Relief Valve) with the specified R-134a part listed in the Adaptation Component Chart. Refer to the appropriate Service Manual for location. In some applications the HPRV is located on the filter/drier. The HPRV on the new filter/drier must be replaced with the new R-134a HPRV.
   5. Replace the HPCO (High Pressure Cutout switch). Refer to the appropriate Service Manual for location. For Vehicles without HPCO switches, install a switch and wiring overlay in the system on the high pressure R-134a adapter switch tee as specified in the Adaptation Component Chart. For SJ/XJ/YJ vehicles, the LPCO (Low Pressure Cutout Switch) is located on the filter/drier and must be replaced with a dual function HPCO/LPCO switch as specified in the Adaptation Component Chart.
   6. Install the filter/drier or accumulator using new R-134a compatible gaskets or o-rings.
   7. Install the compressor on the vehicle using the new R-134a compatible gaskets or o-rings.
   8. Clean old R-12 service ports with a steel brush.
   9. Review the R-134a adapter choices as identified in the Adaptation Component Chart. Refer to the R-134a Charge Port Adapter chart and select the appropriate port adapter which allows for sufficient clearance in the engine compartment to attach R-134a service equipment couplings and/or HPCO switches. Also check for proper clearance between the hood and the R-134a adapter/switch.
   10. Evacuate the system for a minimum of 45 minutes at 26 in. Hg or greater. Charge the system with R-134a with the amount called out in the adaptation Component Chart.
   11. Fill in the required blue R-134a A/C adaptation label, P/N 4762869, using a typewriter or ball point pen. See label illustration for details. If possible, place the new label over the existing R-12 label. If the new label does not completely cover the existing label remove the old label before installing the revised label. If the A/C information is part of a general vehicle information label, cut out only that part that pertains to the A/C system.
   12. Check the system for leaks with approved R134a equipment that meets Chrysler and SAE J1627 specifications.
3. PERFORMANCE TEST PROCEDURE
   1. Connect a tachometer and A/C manifold gauge set.
   2. Set control to A/C, PANEL, and RECIRC or MAX A/C, with the temperature control at "full cool" and blower on "high".
   3. Start engine and hold at 1,000 RPM with A/C clutch engaged.
   4. Engine should be at normal operating temperature and all doors and windows closed.
   5. Insert a thermometer in the left center A/C outlet and operate the engine for five minutes. The A/C clutch may cycle depending on ambient conditions.
   6. With the A/C clutch engaged, compare the discharge air temperature to the A/C performance temperature chart provided.
   7. If the discharge air temperature or discharge and suction pressure are not within the specified range, refer to the diagnostic procedure in the appropriate Service Manual.

 

Renix years:

 

HO Years:

[Pete M]

neat! 

[eaglescout526]

Oh I would also like to add that the labels for this conversion are still very much available at one dealer. I’ll probably order some just to have on hand for those of you who want to add that “dealer” conversion authenticity rather than shade tree/non dealer mechanic conversion done. 

[Red Mistress]

R12 Mineral oil does not mix with 134a PAG oil and will clog the system leading to poor performance.

 

I'm suprised the TSM didn't say to change all the hoses & condensor and flush evaparator.

[Yep]

Try some 414B hotshot.  No conversion needed, direct drop in for R12.  Works a helluva lot better than the crappy 134A.

[Andy in Pa]

On 12/1/2021 at 12:29 PM, Yep said:

Try some 414B hotshot.  No conversion needed, direct drop in for R12.  Works a helluva lot better than the crappy 134A.

  I want to do this conversion, is this legitimate??  It would be so much easier than going to 134A.  Anyone have more information on 414B? 

[Pete M]

there are several r12 substitutes out there.  far as I know, all of them are good to go.

[Andy in Pa]

1 hour ago, Pete M said:

there are several r12 substitutes out there.  far as I know, all of them are good to go.

Yes, I just found one called Enviro-safe R12 and bought it.  I am going to give it a try.  Thanks for the reply!!

[Warren99]

On 9/22/2021 at 10:45 PM, eaglescout526 said:

 

1. 1. Replace the HPRV (High Pressure Relief Valve) with the specified R-134a part listed in the Adaptation Component Chart. Refer to the appropriate Service Manual for location. In some applications the HPRV is located on the filter/drier. The HPRV on the new filter/drier must be replaced with the new R-134a HPRV.
   2. Replace the HPCO (High Pressure Cutout switch). Refer to the appropriate Service Manual for location. For Vehicles without HPCO switches, install a switch and wiring overlay in the system on the high pressure R-134a adapter switch tee as specified in the Adaptation Component Chart. For SJ/XJ/YJ vehicles, the LPCO (Low Pressure Cutout Switch) is located on the filter/drier and must be replaced with a dual function HPCO/LPCO switch as specified in the Adaptation Component Chart.
   3.  

I was under the impression that essentially I could just buy all new components for my r12 system, then change out the orings, and put PAG oil in the compressor then it would be ready to take r134a(with adapter fittings on the compressor ofc). Do I need to do the HPRV and HPCO?

[eaglescout526]

4 minutes ago, Warren99 said:

I was under the impression that essentially I could just buy all new components for my r12 system, then change out the orings, and put PAG oil in the compressor then it would be ready to take r134a(with adapter fittings on the compressor ofc). Do I need to do the HPRV and HPCO?

 

 

Well you should replace the dryer if your converting to 134. But if you’re going back to 12, then you shouldn’t have to do anything. 

[Warren99]

No yea literally everything is getting replaced. The only thing in the a/c system that will be old is two a/c lines(the one going from the condenser to the dryer, and the one going from the dryer to the expansion valve). I believe the new compressor will actually come prefilled with the right mineral oil but I'll have to check.

[Warren99]

I just didn't know anything about the HPRV or the HPCO. Is that necessary when swapping to r134a?

[eaglescout526]

12 minutes ago, Warren99 said:

I just didn't know anything about the HPRV or the HPCO. Is that necessary when swapping to r134a?

It’s more for the 134 pressure so the system knows the right pressure to cut off at vs 12. But yes it’s necessary. You’ll get it with a new dryer and you’ll need to get a new switch which looks the exact same as the older one. Hell the older one will probably work just fine but that’s your call. There really wasn’t a part number for a 134 switch. The catalog just shows one switch and it’s one part number until 1990. 

[Warren99]

10 minutes ago, eaglescout526 said:

It’s more for the 134 pressure so the system knows the right pressure to cut off at vs 12. But yes it’s necessary. You’ll get it with a new dryer and you’ll need to get a new switch which looks the exact same as the older one. Hell the older one will probably work just fine but that’s your call. There really wasn’t a part number for a 134 switch. The catalog just shows one switch and it’s one part number until 1990. 

https://www.rockauto.com/?carcode=1181674&parttype=17507

In this kit I ordered, the compressor is set up to already have r134a PAG oil in it. So would it be safe to assume the dryer has the proper HPRV and HPCO mounted already? 

[eaglescout526]

Yes. It should be. When I did mine I didn’t know this bulletin existed, so I got the new dryer and compressor, everything has been fine so far. 

[Warren99]

Ok sweet, I was not looking forward to spending $80 on 2 switches lol.

[Warren99]

From what I understand,  the dryer is the most sensitive component to the atmosphere. So when installing it, is there some technique or will it be fine to be exposed to the outside air for a few seconds while I hook up the lines and get the vacuum going? I don't wanna accidentally ruin it.

[eaglescout526]

59 minutes ago, Warren99 said:

From what I understand,  the dryer is the most sensitive component to the atmosphere. So when installing it, is there some technique or will it be fine to be exposed to the outside air for a few seconds while I hook up the lines and get the vacuum going? I don't wanna accidentally ruin it.

Make it the last thing you install. But yes it’s fine to be exposed to the atmosphere for a bit considering the system is already exposed. As long as you get it charged soon or aren’t in a incredibly humid climate, you’ll be fine to leave it for a while. But if you are, get it installed and charged as soon as possible to avoid any issues. 

[Warren99]

35 minutes ago, eaglescout526 said:

Make it the last thing you install. But yes it’s fine to be exposed to the atmosphere for a bit considering the system is already exposed. As long as you get it charged soon or aren’t in a incredibly humid climate, you’ll be fine to leave it for a while. But if you are, get it installed and charged as soon as possible to avoid any issues. 

Ok good. Yea the plan was to install everything at once, then immediately vacuum everything out or whatever the procedure is before then charging it with r134a

[eaglescout526]

Sounds good. Vacuuming will remove any and all moisture in the system before being charged. 

[BizarroStormy]

Somewhat related question, when it comes to pressures, can we use the old R12 values to determine charge health when using R-134a? 

 

[eaglescout526]

39 minutes ago, BizarroStormy said:

Somewhat related question, when it comes to pressures, can we use the old R12 values to determine charge health when using R-134a? 

 

That’s a good question.  I don’t see why not at all. Granted the amount of R134 is a bit less if a charge than 12. 

[CommuningWithCoyotes]

The common R12 conversion nowadays is to run propane. There's endless articles and Youtube videos out there on how to do it, as it's extremely simple. Propane has very similar properties to R12 in this application; is extremely safe to use; environmentally friendly compared to any manufactured refrigerant; cheap and reliable; very little needs to be done to convert.