I have a 2000 blazer 4wd 138000 on it.

My AC blows cold but when i am not moving my fan that blows the AC blows about half the power when i am stopped. Keep in mind it hit 110 in vegas today. At night it runs fun stopped or moving and is actual to cold i have to turn it down.

What would cause this, or is it just to dam hot for it to keep up.

 

When ambient temperature rises, it causes A/C high side pressure to rise. When high side pressure rises, the compressor demands more power from the engine. The added demand on the engine at idle causes RPM to drop. When engine RPM drops, alternator output voltage drops causing the blower motor speed to drop, (and lights to dim slightly). Typically the IAC, (Idle Air Controller) will compensate for the RPM drop, but it too relies on voltage and may not react quickly enough, if at all.

A/C is the removal of heat, not the addition of cold. As ambient temperature increases, the more heat the A/C system creates trying to remove it. Perfect example of catch 22... or, the hurrier I go, the behinder I get