• 1 POST
  • 2004 GMC ENVOY
  • 4.2L
  • 6 CYL
  • 4WD
  • 100,000 MILES

Need to know where or what valve to put Freon in truck?

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have the same problem?
Saturday, June 3rd, 2017 AT 8:25 AM

1 Reply

  • 29,778 POSTS

Be aware refrigerant is extremely dangerous to work with. It can cause frostbite and blindness. Professionals wear gloves, safety glasses, and a face shield.

If you have a do-it-yourself kit that includes a charging hose, the fitting will only fit on the low side port. That will be on a pipe or accumulator around the passenger side inner fender. I cannot find a drawing that shows the ports, but it will have a cap to unscrew, then the hose fitting just pushes onto that port. There should be a ring or collar to pull up on to release the fitting. When you are done, be sure to screw that cap back on. The valves in those ports usually leak very slowly. Their only purpose is to hold the refrigerant in to give you time to screw the cap back on. That is what does the sealing.

Chrysler's are the only vehicles you can tell the state of charge by watching for vapor bubbles in a sight glass. The only way to know how much refrigerant is in your system is to recover any that is in there now, then pump in the exact measured amount. When you are just adding, it is possible to over-charge the system. That can lead to liquid sloshing out of the evaporator in the dash and spilling into the compressor. That will cause the compressor to lock up, and it could damage the valves in it. Compressors can only compress a vapor, not a liquid.

The refrigerant gets real cold where it turns from a liquid to a vapor, and you want that to be right in the middle of the evaporator. With too little or too much refrigerant in the system, that point of cooling will be under the hood, not inside the car. That means if your system works better after adding some refrigerant, it is not better to add more. If you reach a point where the compressor runs continuously or cycles off very little, finish off that can, if it is a small fourteen ounces. One, but do not add any more. Home refrigerators will be damaged by adding two ounces too much refrigerant. Cars and trucks are more tolerant because they are bouncing and tilting, and the systems have to be designed to accommodate that, but half a small too much can will likely reduce the system's effectiveness.

Always keep the can upright so only vapor goes into the system. Shaking it will help. The can will become real cold as the liquid in it vaporizes. That is how you can tell it is going in. Expect it to take around fifteen minutes. If it appears nothing is happening, or it is taking too long, set the can in a pot of hot water.

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Saturday, June 3rd, 2017 AT 3:33 PM

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