Air conditioning stops at red lights

Hi, our Chevy Lumina’s air conditioning stops when the engine is idling. Any ideas?

Do you mean that the A/C blower stops working, or that the air from the vents suddenly becomes warm?

Assuming you mean the blower keeps working, but the air ceases to be conditioned, the most likely cause is that the electric fan isn’t working. In order for the air conditioner to work, there has to be airflow going through the condensor (the thing that’s mounted in front ot the radiator). When you’re stopped, this airflow is provided by the electric cooling fan, which should come on when you have the A/C on. You can easily check this yourself by opening the hood while you have the AC going and seeing for yourself if the fan mounted behind the radiator is running. If it isn’t, the most likely fault is the fan relay, though it could be the fan itself and some other related components.