Where do I add air conditioning coolant?

The temperature blend door is stuck on the A/C side ! Do you hear a clicking noise behind the dash ? Has an electrical controlled actuator that switches a door inside heater - A/C box from A/C to Heat . So the blower is blowing air over the A/C evaporator core all the time , not switching !

Vehicle AC engages and blows but no cold air [Archive] - Straight ...

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14 posts - ‎12 authors 07-12-2009, 11:14 PM. The AC in my 2003 GMC Denali SUV appears to be on the fritz. When I use the controls to turn on the AC it blows as usual but a I get no ...

Coolant in system ??
Coolant flowing through 'Heater Core' ??
Code(s) present w/Scanned ??
Possible HVAC issue(s);Blend air door n HVAC box (Under Dash)-Temp Actuator-HVAC control head @ dash.....

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add 134-a and see if compressor kicks on.

look around for "free AC check" at various shops.

Sorry, it can be a few different things.

Possible that the PUMP is not active or working to the desired level . It can also be due to air within the hydraulic system and will require a reset on the unit.
Make sure that the belt is not slipping on the pulley .

Yes that is where you add coolant, but the sensor may be bad if the coolant level is within the lines on the tank marked Hot and Cold

If this happens when you are idle, and then you get hot air as you drive, most likely you have low coolant and it only cycles as you drive. Get approved dextrom gmc coolat and cap off your coolant it is most likely low.

lack of coolant

Usually there is a petcock on the lower edge of the radiator either on the right or left side. If you can not find it at all then disconnect lower radiator hose from either radiator or water pump. This will make a small mess but will drain the coolant.

fill the coolant recovery at or to cold level only.