2003 GMC Envoy



April, 5, 2010 AT 4:39 PM

Air Conditioning problem
2003 GMC Envoy 6 cyl Two Wheel Drive Automatic 55,343 miles

Dear everyone,

I have been experiencing a few problems after 6+ years of nothing. The problems began with a " clicking" noise coming from the engine. I took it to a mechanic in Brooklyn NY and they told me that it maybe from the air-compressor not clicking on/over and/or the fan hitting something.

The bottom line is that after replacing the battery (which had nothing to do with the noise) and changing the oil and transmission fluid the clicking sound has vanished.

However, we I turn on the A/C there is NO cold air. I think it needs freon but not sure.

If it is freon, can I go to a PepBoys and buy it? I saw someone who wrote this:

" The easiest way to recharge your air conditioner is to go to auto-zone, or like store and purchase one of the small recharge canisters they sell. It is an aerosol size can, (slightly larger though) and has a rubber tube extension. It looks a lot like a fix-a-flat can. This simply hooks into the vehicle and through pressure it transfers freon into the AC unit. This is the best way because if you buy a whole tank of freon it will most likely be a waste of money and a hazard to your storage environment. Also, in some cases you need requirements before you purchase large quantities of freon.&Quot;

I am pretty sure (90%) there is NO leak as I have never seen anything dripping from under the car. However I am not a mechanic.


I really don't want to get ripped off taking it somewhere for them to do something I could do myself.

Thank you!


3 Answers



April, 5, 2010 AT 6:37 PM

You won't see refigerant leaking because it vaporizes. There is a special oil that circulates in the system. You might see some residue at the point of a leak. Chrysler systems are very easy to recharge the way you posted because they have a sight glass. When the vapor bubbles disappear, the system is full. GMs have no way to tell how much charge is in the system. Overcharging will lead to poor cooling because the liquid will turn to a vapor too late, on its way to the compressor. The cooling will take place under the hood instead of in the passenger compartment. A severe overcharge can damage the compressor too if liquid sloshes into it. It can only handle a vapor. The only accurate way to know how much refrigerant is in the system is to recover, (drain) the remaining refrigerant out, then pump in the exact measured amount called for.

If you want to try to add one can of refrigerant yourself, since it's not cooling now, one can will not likely cause an overcharge condition. You must be aware though that most professionals will wear a safety shield because in the event of a leak, vaporizing refrigerant can freeze eyeballs and cause frost bite.

The hose that comes with the kit screws onto the low side hose on the truck. It won't fit on the other hose. The engine must be running so the compressor will draw the pressure down in the hose going into it. The can must remain upright so the refrigerant will boil off and enter the system as a vapor. If you turn the can upside down, liquid will enter the system and cause the compressor to lock up. If it takes more than a couple of minutes to enpty the can, place it in a container of hot water. That will really speed things up, but still keep the can upright.

It is common for the charge to slowly be lost after six years, so there might not be a leak that you can find. Be sure to use R-134, not the older R-12.




April, 6, 2010 AT 8:39 AM

I appreciate your quick response. I am going to look into this asap. I am not quite confident in getting a can and doing this procedure on my own in fear of losing my " eyeballs" per what you said.

Ultimately I am afraid of taking it somewhere and them telling me I need to spend thousands of dollars on a new A/C system of something.

I will contact my (new) local mechanic and have them take a look.

Question: Will they be able to look at the freon and see if that's the problem? Or is this something I can/should do on my own first?

Thank you in advance!




April, 6, 2010 AT 11:02 AM

What they will do is connect a pair of gauges to read the pressures while the system is running. The pressures don't mean anything when it is at rest. Some of the refrigerant is liquid and some is vapor. When some vapor is removed, either through a leak over time or by sucking some out with a machine, the pressure in the system goes down. With lower pressure, more of the liquid turns to a vapor and expands which causes the pressure to go right back up. This will continue to happen as long as there is any liquid still in the system.

When the system is running, the compressor causes there to be different pressures in different places. When there isn't enough refrigerant, there isn't enough to compress so the " high side" pressure won't build up high enough and the low side pressure will get drawn down too low. That's the clue.

When your system is so low that it no longer cools, adding one can of refrigerant won't be too much to overcharge it. You don't have to be afraid to do this yourself. Just have respect for the material and don't stick your face near the can. The warning about frost bite and freezing your eyes was only because to most people, that is not common knowledge. If you follow the directions that come with the kit, the job should take less than a half hour and will save you a bunch of bucks. The only problem would be if the system stops working again within a few hours or a few weeks, there is a leak that must be found and repaired.


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