How do you charge the AC in a 98 Surbuban?

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by zuper8, Jul 3, 2009.

  1. zuper8

    zuper8 Rockstar

    It has rear AC as well. I want to charge it up, and have never done it before. Where do I open it up? I know I was told the "low side", but not sure exactly which one. I have a little pressure gage so I own't overfill. Also, do I have to charge the front and rear separately?
  2. L0sts0ul

    L0sts0ul Rockstar 100 Posts

    TBH I would take it to a mechanic and get him to do it, as AC refridgerant is something I don't mess with.
  3. zuper8

    zuper8 Rockstar

    Yeah I have avoided it as well, but my buddy showed me how to do it on my Bonneville, and it seems that as long as you keep an eye on the pressure you should be fine. I mainly just want to know where on which line to put the refridgerant in.
  4. Mean_Green_95

    Mean_Green_95 Epic Member 5+ Years 1000 Posts

    The high pressure and low pressure lines have different size fitting, so which ever one it your tool fits on is the correct one.
  5. Springthing

    Springthing Epic Member 5+ Years 1000 Posts

    Anyone else have any more thoughts on this? Front vs rear, etc? I'm kind of curious myself.
  6. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    I have charged AC systems a bunch of times. The decent gauge set is like $80 at Autozone. It's not a bad investment. You can watch the low and high sides at the same time, and add R134 without removing either gauge. At the very least, get a fill kit with a long hose. Two feet or more.

    My 97 has the Vortec 350, should be the same as yours. I am 99% sure it's one system. One compressor, one condenser, two evaporators. I don't know if there is one or two accumulators. On top of the compressor is two fittings. The small port on the right is the low side. Little port/Low side. It draws from the accumulator, which is connected to the evaporator. This is the port you want to use to add R134. When using the small cans of R134, I use a pail filled with HOT water. It will help the R134 vaporize faster, build more pressure in the can, and keep the valve from freezing.

    Here you go. Put both ACs on coldest, fan on hi. Take a static low side reading with the engine off, and start the engine to take your low side reading. You can use these to compare after you fill up. Connect your hose to the low side, the can on the other end, and run the needle valve down through to puncture the can seal. Start the engine. Put the can in the bucket of water, and open the needle valve. If your hose has a separate vave, open it. Keep the can moving through the water. Back and forth, tip over and back. Keep the valve in the water, that's the part that freezes. When the can feels empty, close your valves, and take your low side reading with the engine running.

    This is an OK chart for what your pressures should be. As the ambient (outside) air temp increases, the pressure in your system will come up. When your pressure is right for the air temp, you are OK. I have overfilled slightly, with no ill effects. These numbers are WITH THE ENGINE RUNNING AND AC ON.

    I just took some pics with my cell phone, but can't seem to get them on the computer right now.

    Where's my 16 year old son when I need him?!?!?
    Last edited: Jul 3, 2009
    1 person likes this.
  7. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Did you try it? I was Autozone earlier this week, they have a gauge kit for $40. Well worth the money. You can keep checking your pressure as add R134.
  8. IrishBrewer

    IrishBrewer Rockstar

    The best thing to do would be to evacuate the system with a vacuum pump and a set of gauges. After evaacuating , turn off the pump to check to see if it holds a vacuum by looking at the gauges. If not, you have leaks that need to be addressed (easy fix would be to use a sealer or sealer/refrigerant combo, if that doesn't work, you have to find the leak by other means such as a UV dye or leak detector). If you do have a leak, you'll want to install a new dryer canister because these contain consumable dessicant that no longer works after it has been exposed to moist air. If you install a new one, make sure to also add the proper amount of PAG oil to the canister (determined by draining the oil out of the removed canister).

    Once the system is evacuated, you then add the proper amount of refrigerant for your AC system. This is important because an overcharged system will not run well.

    There is a Haynes manual on AC systems that is very good and has tables of oil/refrigerant.

    You can get a set of gauges and a vacuum pump at *some* Autozone stores through their loan a tool program - free when you bring them back. Only one of several stores in my area had these tools as part of this program. Someone said that it was because it was a "hub" store.

    The method outlined above is more time consuming way to do a charge but it is the best way to reliably get the right amount of refrigerant/oil in the system. The next best way would be the pressure charts and a good gauge set as mentioned by other posters.
  9. zuper8

    zuper8 Rockstar

    Well, thank you everyone for the informative posts. It has helped me charge my other vehicle. However, the Suburban could not be helped, for when I turned on the AC and went to start putting in refrigerant (engine running of course), the compressor was not spinning :( Guess I have an expensive problem that won't be getting fixed any time soon
  10. Mean_Green_95

    Mean_Green_95 Epic Member 5+ Years 1000 Posts

    Check your ac relay before u bring it to a shop. It might just be old and worn out.

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