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Charging the A/C System on a 1st Gen Tacoma (or 3rd Gen 4Runner)

Any time any component of your A/C system is replaced, it's a necessary to recharge the system with refrigerant. This generally costs in the $150 range at the shop, but you can do it yourself for under $100 the first time, and have the necessary tools to do it for $20 any time after that!

And, if you're doing it as part of replacing other parts of your A/C system, here's how you do it all:

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Tools and Supplies

To recharge your A/C, you'll need the following tools:

  • A/C Diagnostic Manifold Gauge Set - this gauge set would allow me to test the system and to charge the system with 134a refrigerant once I knew it would hold pressure.
  • A/C Vacuum Pump - working in tandem with the manifold, the vacuum pump removes all air (and more importantly moisture) from the A/C system prior to charging.
  • 2, 12oz cans of 134a A/C refrigerant - this is the stuff that makes it chilly.
  • A/C Can Tap for R134A Refrigerant - connects the cans of refrigerant to the manifold gauge.

Recharging the A/C System

Note: The FSM states that the A/C system on a 1st gen Tacoma holds 21.16oz +/- 1.76oz of R134a refrigerant. As such, the process below outlines using two (2), 12oz cans of refrigerant (24oz total) since that can size is a common size. Given that the process of transferring the material is likely to lose a bit in the process - inside the manifold set if no other place - this places essentially the correct amount of refrigerant into the system.

For a visual of the recharging process, this video does a good job of walking through most of the steps. I found it useful to watch the video, and then follow these steps below.

  1. Start by hanging the A/C Manifold Gauge Set on the hood latch and ensure that all valves on both ends of the red and blue lines are in the closed position.
  2. Secure both the high (red) and low (blue) pressure lines to the valves on the lines that pass through the firewall. Note: the fittings are quick connect style, and are different sizes, so they'll only fit on the appropriate respective line.

  3. Attach the vacuum pump to the yellow line and begin pulling a vacuum.
  4. Open the high and low pressure valves on the manifold, and also open the high and low pressure valves on the quick connect fittings. Note that the quick connect fittings "open" a Schrader valve in the A/C lines by depressing it; so turn the valves to open but don't over depress the Schrader valve.
  5. Run the vacuum pump for at least 30 minutes to evacuate all air and moisture from the system. During this time, the vacuum should be pulling between -25inHg to -30inHg depending on your altitude.

  6. After 30 minutes, turn off the vacuum pump and let the system sit for at least another 30 minutes to make sure that the vacuum holds at whatever vacuum is indicated on the manifold. Any decrease in vacuum at this point means that there is a leak in the system that must be addressed prior to charging the system.

  7. After 30 minutes of maintaining a constant vacuum, close both the high and low pressure valves on the manifold and remove the yellow line from the vacuum pump. Attach that yellow line to a the can tap (sometimes included with the manifold gauge set) after connecting the can tap to the first can of R134a.
  8. Start the truck and turn the A/C all the way to cold, with the fan speed on high, and the windows open. Have a helper keep the engine at 1500 RPM.
  9. On the manifold, open the valve for the low side (generally blue and on the left), making sure the high side (red) valve is closed.
  10. Screw in the top of the can tap so that it pierces the seal on the 134a refrigerant can, then back off the can tap so that refrigerant can begin flowing into the system. As the refrigerant is flowing, repeatedly rotate the can from 12-o'clock to 6-o'clock to assist in the transfer of gas and liquid. Note: the can will get very cold as this procedure takes place.
  11. Once the can is completely empty, close the low side (blue) valve and make sure the can tap is completely backed out of the R134a can. Remove the empty can from the tap, and screw on the second 12oz can of refrigerant. Repeat the process of transferring refrigerant from the second can into the system. (steps 9 and 10)
  12. When all the refrigerant has been transferred out of the second can, close off both the low side (blue) and high side (red) valves on the manifold. Completely insert the can tap into the now empty can of R134a to seal it and isolate it from the system.
  13. Turn off the engine.
  14. Equalize pressure on the high and low sides of the system by slowing opening the high side (red) valve on the manifold gauge. This will recover a small amount of refrigerant that's currently in the manifold lines and push it into the system.
  15. Once the system is equalized, close the high side (red) valve on the manifold gauge and also close the two quick connect valves before removing them from the lines passing through the firewall. Note that upon removal, a tiny bit of refrigerant may escape - be ready for it by wearing gloves and safety glasses.
  16. Lastly, open all of the valves slowly to release pressure in the manifold gauge. Again, some refrigerant will escape - be ready for it by wearing gloves and safety glasses.

And with that, you're done! Button up anything that's still not put together on the truck pat yourself on the back for a job well done. It wasn't that hard, with the right tools now, was it?

 

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