Hyundai Elantra - A/C and Heater Problem

My wife drives a 2003 Hyundai Elantra. When the A/C is on in the summer, it takes a long time for the air to cool. Even after the air turns cold, when the car comes to a stop or slows down, the cold air starts blowing hot again. The air does not turn cold again until the car starts to drive and reaches about 25-30 mph. The reverse problem occurs with the heater in the winter. The air does not blow hot until long after the engine warms (about 5-10 minutes after temperature gauge reaches the midway point), and the air blows cold once the car comes to a stop. The hot air does not resume until the car gets moving again. Thanks for any help you can provide.

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i am having the exact problem with my 2003… did you ever figure out what the problem was?

Not yet. I hope to get it into a shop in the coming weeks. If I find out what it is, I’ll be sure to post a reply.