2000 Chevy Astro overheating

My 2002 astro was doing the same thing - overheating only when air conditioning was on. After replacing the thermostat and fan clutch I finally replaced the radiator and that solved the problem. The front of the radiator could not be seen because the a/c condenser blocked my view. It turned out that a cat had been climbing up into the engine compartment and sitting next to the radiator to keep warm in the winter, leaving a thick coating of cat hair on the front of the radiator. Now I can sit in traffic on a hot summer day with the a/c on with no problems. Paid 130$ for the radiator at salvo auto parts.