My ac works at high rates of speed but not when driving slow or stopped

Hello, sounds like a possible air flow concern. If your condenser / cooling fan under the hood is not working at the times it is needed for AC system performance, it can prevent the refrigerate from turning back into a gas before hitting the compressor again. Testing is needed, as this is only a guess, but air flow or fan creating air flow is commonly a cause. www.repairpal.com/repair-shops