My a/c does not blow cold when idling - 2003 Hummer H2

I can't say much without having the actual code.
When the ac stops blowing cold at idle, the most common reason is not enough air flowing thru the radiator, or the radiator fan is not running and the only air flow is when the vehicle is moving.

As per your problem mentioned.There are few solved help links to troubleshoot these problems.Go through the list and Click the link below:----
Air conditioner blows air but not cold air http://repairhelpcenter.blogspot.in/2012/07/air-conditioner-blows-air-but-not-cold.html

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Car overheats and Air blows hot at idle? http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html

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Heat blows cold on drivers side and hot on passenger side? http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html---------- Hot air on the driver's side vents only? http://repairhelpcenter.blogspot.com/2012/01/hot-air-on-drivers-side-vents-only.html

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2005 Chrysler PT Cruiser: A/C Blows Warm? http://whoisbyme.blogspot.in/2012/06/2005-chrysler-pt-cruiser-ac-blows-warm.html

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1992 Toyota Camry: A/C Control light Flashing and A/C not Blowing Cold? http://technoanswers.blogspot.in/2012/04/1992-toyota-camry-ac-control-light.html

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No heat, blower blows only cold? http://technoanswers.blogspot.in/2012/02/no-heatblower-blows-only-cold.html

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These will help.
Thanks.

For rough idle issues and problem troubleshooting,go through the help links provided below :----- van idles rough?

http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html

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will not idle when cold?

http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html

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runs lean and idles rough?

http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html

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Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

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Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

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Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

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Idle Air Control (IAC) Valve Replacing?

http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

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Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

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Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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This will help.

Thanks.

For rough idle issues and problem troubleshooting,go through the help links provided below :-----van idles rough?

http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html

---------
will not idle when cold?

http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html

----------
runs lean and idles rough?

http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html

-----------
Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

------------
Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

----------
Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

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Idle Air Control (IAC) Valve Replacing?

http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

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Replace Idle air control valve?

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Test Idle Air Control (IAC) Valve?

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Idle Air Control (IAC) Valve operation?

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Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

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Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

------
While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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This will help.

Thanks.

For rough idle issues and problem troubleshooting,go through the help links provided below :-----van idles rough? http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html---------will not idle when cold? http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html
----------runs lean and idles rough? http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------Engine stumbles coming off idle when warm? http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html
------------Erratic idle on car? http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html
----------Low idle when cold out side? http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
---------Idle Air Control (IAC) Valve Replacing? http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html----------Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

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Car overheats and Air blows hot at idle? http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
------While stop engine idles like cylinder missing? http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------This will help.Thanks.

make sure you have the right thermostat installed

temp should rise while idling unless thermostat is stuck open and not letting heat build up

You have an air pocket in the cooling system. To bled it out you will have to park vehicle on an incline or jack up the front end untill the radiator cap is higher than the heater core. The remove radiator cap and run engine until warm then hold rpm to about 1200 rpm's and top off coolant level until you have no more bubbles.

1.maybe your thermostat is no opening or closing.
2. not enough Ant-Freeze
3. Low on water

With more details on the engine i may be able to help you more. for example what is the temp reading after it idles awhile or does it blow warmewr when driving ?

The refrigerant level may still be to low or the compressor is not working properly.