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Saturn Forum - Saturn Enthusiasts Forums (https://www.saturnforum.com/forum/)
-   Saturn S Series Sedan (https://www.saturnforum.com/forum/saturn-s-series-sedan-27/)
-   -   S Series A/C Air Conditioning Restoration Guide by Rootmazur (https://www.saturnforum.com/forum/saturn-s-series-sedan-27/s-series-c-air-conditioning-restoration-guide-rootmazur-13699/)

Rootmazur Mar 30, 2025 12:01 AM
S Series A/C Air Conditioning Restoration Guide by Rootmazur
 

The Problem


My A/C had a failed and leaking compressor, which can contaminate the entire system with shrapnel and debris.
https://cimg5.ibsrv.net/gimg/www.sat...c0ee371cb2.jpg
This compressor was original to the vehicle, and the A/C had never worked since I acquired the car.

https://cimg3.ibsrv.net/gimg/www.sat...d0e1fdf0df.jpg
A black light reveals the compressor is leaking, quite severely, and may have additional internal problems.

Ideally, a compressor should not resemble a reenactment of the Chernobyl disaster.

The Solution (and purpose of this guide)

This guide covers an A/C system overhaul of the 1997 Saturn SL1. When a compressor fails, it is possible that it may have contaminated the system with debris and shrapnel. Therefore, simply replacing the compressor is not sufficient. Without dealing with the potential contamination properly, simply replacing the compressor is a recipe for more problems down the road. That is why an overhaul is the recommended procedure. The guide should also be applicable to other models of the Saturn S-series. It is based on a plan that I made for myself to restore the air conditioning on my 1997 Saturn SL1. I am sharing it here as an open source contribution for other Saturn S-series enjoyers. The guide assumes that the user has basic mechanical knowledge and access to tools and parts.

Summary of the guide:

Replace:
The compressor, discharge hose, the condenser, the receiver drier, and the thermal expansion valve;

Flush:
The liquid line, the evaporator core, (and the new suction and discharge hoses)

Charge the system:
With 1.5 lbs of r134a refrigerant

Test the performance:
Using manifold gauge readings.

How to Use the Guide

The guide is organized into nine (9) phases. Each phase is accompanied by three (3) sections: 1) A section for the suggested tools and parts that will be needed. 2) A section with instructions and images. 3) A section with some of my own comments about what I experienced and learned when completing each phase.

The instructions sections include many hyperlinks to the charm.li Saturn service manual for the 1997 SL1, and assumes that the user will use the links to read, understand, and perform the service that is described at each step. Anything that is underlined is a hyperlink! If you are using this guide for a different year or model of Saturn S-series vehicle, such as a 1995 Saturn SC2, make sure you use the appropriate charm.li page for that vehicle.

The instructions also include captioned photographs that I took while completing this project on my own Saturn. Most of the photographs are hidden using "Spoiler" tags, so that they can be minimized for ease of use. To view the photographs, click on the plus (+) symbol next to the spoiler. To minimize the photographs, click on the minus (-) symbol next to the spoiler.

Use the tools/equipment lists to prepare ahead.

General A/C System Info

Air conditioning is one of the most important inventions of all time. I suggest watching this 8 minute video to for a quick explanation of how a vehicle A/C system works before performing any kind of repair on an A/C system.


S-series A/C systems include a compressor, a condenser, a receiver drier (also called an accumulator), an expansion valve, and an evaporator core. The A/C system also includes hoses and lines to carry refrigerant through the system.

S-series A/C systems use R134a refrigerant. For the refrigerant to function correctly it must be free from contamination by air and moisture. This is achieved by creating a vacuum with a vacuum pump to create a vacuum in the system before charging it.

S-series A/C systems are lubricated by PAG oil (polyalkylene glycol). PAG oil dissolves into the refrigerant and is distributed through thesystem by the refrigerant itself. PAG oil is added to the system components during the overhaul

R134a basics

Spoiler
 

Cautions and Disclaimers

This is not a substitute for professional service.

Incorrect handling of refrigerant/oil can damage components or be hazardous.

Always follow EPA/local regulations for refrigerant handling.

Suggested Tools/Equipment

Hand Tools
  • Channel locks or pliers (to remove intake hose clamp)
  • Flathead screwdriver (for disconnecting electrical connectors)
  • Metric flared crowfoot wrenches (for torque spec on hose fittings)
  • Metric open-end/box-end wrenches
  • Metric sockets
  • Ratchet drive
  • Socket extensions
  • Torque wrench (including low-torque type for fittings)

A/C System Tools
  • A/C flush kit
  • A/C vacuum pump
  • Blowgun attachment
  • Digital scale
  • Nozzle tap for R134a canisters
  • R134a manifold gauge set
  • UV flashlight
  • Vent thermometer
  • Very narrow-tip rubber nozzle

Replacement Parts
  • Compressor
  • Condenser
  • Discharge hose
  • O-ring kit (ideally use original O-rings, but not always possible)
  • Receiver drier
  • Suction hose
  • Thermal expansion valve
  • Throttle body gasket

Fluids & Consumables
  • Flush solvent
  • PAG 46 refrigerant oil (8 oz is plenty)
  • R12 refrigerant oil (for lubricating O-rings; hard to find but worth it)
  • R134a refrigerant (need at least 1.5 lbs)

Other Tools
  • Air compressor
  • Camera
  • Floor jack
  • Jack stands or ramps
  • Plastic tubing
  • Small hose clamp

-------
End of introduction

Rootmazur Mar 30, 2025 12:02 AM

Phase 1: Remove Components to Access Work Area



Suggested Tools/Equipment:

  • Ratchet drive
  • Metric sockets
  • Socket extensions
  • Channel locks or pliers (to remove intake hose clamp)
  • Throttle body gasket
  • Flathead screwdriver (for disconnecting electrical connectors)

Instructions:


  1. Remove the air box cover, intake hose, and the throttle body assembly.

    https://cimg6.ibsrv.net/gimg/www.sat...12481e3f50.jpg
    The intake air hose, air filter cover, and throttle body are removed. This provides enough space to work on the thermal expansion valve.
  2. Remove the front left headlamp to gain access to the condenser inlet/outlet. The charm.li manual has no procedure for how to do this, but the video below quickly explains how to do it. The relevant information begins at 1:38. The video shows the procedure on the passenger side, but it's exactly the same for the driver side, too. Only the driver side headlamp needs to be removed. Don't forget to unplug the electrical connectors for the low beam and high beam bulbs, and to unscrew the turn signal socket from the headlamp assembly.


    https://cimg4.ibsrv.net/gimg/www.sat...ad5bf91b52.jpg
    The driver side headlamp is removed, providing space to access the condenser inlet and receiver drier hose.

-------
End of Phase 1

Comments:

The charm.li service manual does not instruct you to remove the throttle body. However, I believe it would be impossible to work on the thermal expansion valve with the throttle body installed, so I suggest removing it. If you have never removed the throttle body before, it would be wise to have a replacement gasket on hand in case the old one disintegrates during the removal process. If you want to, this would also be a good opportunity to clean your throttle body.

Rootmazur Mar 30, 2025 12:02 AM

Phase 2: Photograph the Routing of the Hoses and Lines



Suggested Tools/Equipment:

  • Camera
  • Floor jack
  • Jack stands or ramps (to take photographs from underneath vehicle)

Instructions:

  1. Take photographs to record how the suction hose is routed (compressor to thermal expansion valve).
    Suction hose (marked with yellow)
    Spoiler
     
  2. Take photographs to record how the discharge hose is routed (compressor to condenser inlet).
    Discharge hose (marked with teal)
    Spoiler
     
  3. Take photographs to record how the condenser outlet hose is routed (condenser to receiver drier).
    Condenser to receiver drier hose (marked with red)
    Spoiler
     
  4. Take photographs to record how the liquid line is routed (receiver drier to thermal expansion valve).
    Liquid line (marked with blue)
    Spoiler
     

-------
End of Phase 2

Comments:

The purpose behind this phase is to establish a record of how the hoses are routed through the engine compartment. When the time comes to reinstall components, knowing how the lines are routed is key. This step will also help you familiarize yourself with how the AC system components are interconnected. You can rely on the photographs shared here to help you identify your components, but it would be best to take your own photographs because it is possible that your vehicle configurations are not identical.

Rootmazur Mar 30, 2025 12:03 AM

Phase 3, Part 1: Component Removal (and Some Installation)



Suggested Tools/Equipment

  • Floor jack
  • Jack stands or ramps
  • Ratchet drive
  • Metric sockets
  • Metric open end/box end wrenches
  • Metric crowfoot wrenches (for torque spec on hose fittings)
  • Low-torque torque wrench
  • R12 refrigerant oil (for lubricating O-rings; hard to find but worth it)
  • PAG46 refrigerant oil (8 oz. is plenty)
  • Replacement condenser
  • Replacement receiver drier
  • Replacement compressor
  • Replacement O-ring kit (ideally use original O-rings, but not always possible)

Instructions:

  1. Review the O-ring bulletin.
  2. Remove the old condenser.
    Spoiler
     
  3. Install the new condenser.
    Spoiler
     
  4. Add 22.5 ml (3/4 oz.) PAG oil to condenser.
    Spoiler
     
  5. Remove the old receiver drier.
    Spoiler
     
  6. Install the new receiver drier.
    Spoiler
     
  7. Add 30 ml (1 oz.) PAG oil to the receiver drier.
    Spoiler
     
  8. Connect the receiver drier to the condenser with a lubricated O-ring.
    Note1: The service manual instructs to use R12 mineral oil to lubricate O-rings and specifically warns against using PAG oil. R12 systems have been largely phased out of use, so the oil was difficult to find. However, it is available on Amazon (in a large size) here.
    Note2: This fitting requires a crowfoot wrench to properly torque. The fitting for the outlet on my system is 22mm, and the fitting for the inlet is 24mm.
    No Photo
  9. Remove the compressor suction hose.
    Spoiler
     
  10. Remove the compressor discharge hose.
    No Photo
  11. Disconnect the liquid line from the thermal expansion valve.
    Spoiler
     
  12. Remove the thermal expansion valve.
    Spoiler
     

-------

Phase 3 continues in next post...

Rootmazur Mar 30, 2025 12:03 AM

...Phase 3 continued: Component Removal (and Some Installation)



Instructions:

  1. Remove the old compressor
    Spoiler
     
  2. Install the new compressor
    Spoiler
     
  3. Prime the new compressor with 30 ml (1 oz.) of PAG oil.
    Spoiler
     
    Note: After adding oil, it is wise to place the port covers back on the compressor to prevent contamination from any debris or dust while working.

-------
End Phase 3

Comments:

The order of operations in this phase is sequenced in a way that made logical sense to me. It is not necessarily required to do everything in this particular order. I will also give the warning that you should not necessarily be following every single step of the CHARM instructions, because they are designed to describe the process of servicing single components, and this project services many components. So, you should not be following every single instruction exactly. Remember to apply your own intelligence to the project! Also, I have attached the documents that came with my replacement compressor, as they contain important information about the compressor.

Rootmazur Mar 30, 2025 12:04 AM

Phase 4: Flush



Suggested Tools/Equipment

  • A/C flush kit (Recommended: this)
  • Flush solvent (Recommended: 3 cans of this)
  • Air compressor
  • An additional, very narrow-tip rubber nozzle
  • Blowgun attachment
  • Plastic tubing
  • Small hose clamp

Instructions

  1. Flush the evaporator core with solvent
    Spoiler
     
  2. Dry the evaporator core with compressed air
    No photograph. Blow compressed air through the evaporator core until it is dry.
  3. Flush the suction hose with solvent
    Spoiler
     
  4. Dry the suction hose with compressed air
  5. Flush the discharge hose with solvent
  6. Dry the discharge hose with compressed air
  7. Flush the liquid line with solvent
    Note: Flushing the liquid line is particularly challenging because the line opening is difficult to reach. Uninstalling the liquid line is a difficult procedure, and the part is not readily available for sale if it were to break. Although it is awkward, I recommend flushing the liquid line with it installed. The liquid line is also very narrow, which is why you will need an airgun nozzle that is very soft and narrow.
  8. Dry the liquid line with compressed air

-------
End of Phase 4

Comments:

It is recommended to use a whole can of solvent to flush the evaporator core.

Rootmazur Mar 30, 2025 12:04 AM

Phase 5: Final Installations and Oil Distribution



Suggested tools/equipment

  • Torque wrench
  • Metric sockets
  • Flared metric crowfoot wrenches (for torque spec on hose fittings)
  • Replacement suction hose
  • Replacement discharge hose
  • Replacement thermal expansion valve

Instructions:

  1. Add 67.5 ml (2 ¼ oz.) of oil to the evaporator core. (I suggest adding it through the liquid port.)
  2. Install new thermal expansion valve
    Spoiler
     
  3. Reconnect liquid line to thermal expansion valve and receiver drier
    Spoiler
     
  4. Install new low-pressure suction hose
    Spoiler
     
  5. Install new high-pressure discharge hose
    Spoiler
     

-------
End of Phase 5

Comments:

Leave the headlamp uninstalled until Phase 8 is complete, after the leak test.

Rootmazur Mar 30, 2025 12:05 AM

Phase 6: Pull Vacuum and Leak Test



Suggested Tools/Equipment

  • R134a manifold gauge set
  • AC system vacuum pump

Instructions:

  1. Close all valves on the manifold gauges.
  2. Attach high and low gauge nozzles to the high- and low-side service ports.
  3. Thread the yellow center gauge nozzle to the R134a port of the vacuum.
    Spoiler
     
  4. Open both high and low nozzles on the service ports, and open both high and low valves on the manifold gauges.
  5. Turn on the vacuum.
  6. Monitor the low-side gauge until the reading is nearly -30 inHg.
    Note: The best vacuum you can achieve depends on your elevation above sea level. Higher elevations result in lower maximum achievable vacuum readings. For example, at sea level, a perfect vacuum reads about 29.92 inHg, while at higher elevations, a reading of 27–28 inHg may be normal.
  7. Close the high service port valve, then close the high manifold gauge valve, then close the low manifold gauge valve.
    Note: The low service port valve should be left open to continue reading negative pressure.
  8. Turn off the vacuum.
    Spoiler
     
  9. Monitor the low-side pressure reading for 10–15 minutes (or longer).
    • If vacuum is lost (leaks out), find the leak and repair it.
    • If vacuum holds, close the low-side service port valve.
  10. Reinstall throttle body
  11. Reinstall the intake hose and air box cover.

-------
End of Phase 6

Comments:

If all has gone well, the vacuum should hold. If the vacuum is not holding, you must locate the leak and repair it before proceeding. It is impossible to charge the system with a vacuum leak.

Rootmazur Mar 30, 2025 12:05 AM

Phase 7: Refrigerant Charge



Suggested Tools/Equipment

  • R134a manifold gauge set
  • A/C vacuum pump
  • R134a refrigerant (need at least 1.5 lbs)
  • Nozzle tap for R134a canisters
  • Digital Scale

Instructions:

  1. Refrigerant capacity – The system must be charged with 1.5 lbs (0.68 kg) of R134a refrigerant.
  2. Close all valves and service ports on the manifold gauge.
    Note: High- and low-side manifold gauge connectors should still be connected to the service ports, and the high and low manifold gauge hoses should still be holding the vacuum from Phase 6.
  3. Thread the end of the yellow center hose to the refrigerant tap nozzle.
    Spoiler
     
  4. Thread the can of R134a onto the tap nozzle.
  5. Turn on the nozzle to allow R134a to flow into the yellow service hose.
  6. Loosen the yellow service hose connection at the manifold gauge slightly to allow air to be forced out of the hose by the refrigerant.
    (Warning: Some refrigerant will escape.) Ensure all air is removed from the yellow hose.
  7. Place the can of R134a carefully onto a digital scale.
  8. Make a note of the starting weight of the can. This will be used to calculate how much R134a has been added to the system.
  9. Start the vehicle. Turn on the A/C, set the blower motor to maximum, and the temperature to cold.
  10. Open the low-side valve of the manifold gauge.
  11. Open the low-side service port valve.
  12. Refrigerant is now flowing into the system.
  13. Open the high-side service port valve (not the manifold gauge valve!)
  14. Monitor the weight reading on the scale to track how much refrigerant is being added. Do not overcharge the system.
  15. Follow the instructions on the can for the charging process. This usually involves tilting the can 90 degrees to its side and back upright periodically.
  16. When the can is empty or nearly empty, close all manifold gauge valves, disconnect the can, and connect the next full can.
    Be sure to loosen the yellow service hose connection at the manifold gauge slightly to purge air.
    (Warning: Some refrigerant will escape.) Ensure all air is removed from the yellow hose.
  17. When 1.5 lbs of refrigerant have been added, close the low-side manifold gauge valve.
  18. Close the refrigerant tap nozzle.

-------
End of Phase 7

Comments:

I don’t have many photographs to accompany this section, as there are many resources online about how to use manifold gauges and charge a system with refrigerant. I’m probably repeating myself, but before beginning this process you should have a firm understanding of the fundamental concepts behind charging an A/C system with refrigerant. These instructions are only a logical and sequential framework to operate from. Be certain you understand what it is that you are doing and why you are doing it at each step. A single mistake can cause the system to become contaminated with air and moisture, and to lose vacuum.

Rootmazur Mar 30, 2025 12:06 AM

Phase 8: Test Completed System



Suggested Tools/Equipment

  • Vent thermometer
  • UV flashlight
  • Manifold gauge set

Instructions

  1. Place a thermometer in the center A/C vent and set the system to blow the air as cold as possible. Ideally, the vent temperature should be between 40 and 50 degrees Fahrenheit.
  2. Ensure high- and low-side pressures are correct for the given environmental conditions. If they are not, diagnose the issue and correct it.
    Spoiler
     
  3. Use a UV light to thoroughly inspect the entire system for leaks.
  4. If any leaks are found, repair them and return to Phase 6.

Comments:

When testing system performance, it is common for the initial manifold gauge readings to be slightly outside the prescribed PSI range. This is because it can take time for the system to balance the distribution of PAG oil and refrigerant. If your readings are out of the prescribed range, but somewhat close, do not rush to correct them by adjusting the refrigerant charge. Drive the vehicle and monitor the system. A/C systems also tend to perform better while the vehicle is driving and operating above idle RPMs.


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