[JL8Jeff]

My 93 wouldn't heat up much with the 160 t-stat. If you look at the heater lines with their 90 degree bends, it explains why the core gets blocked up. The flow is minimal at the core so you need to backflush it. GM used that cooling system sealer that also tends to block things up in some places. I had to backflush my 93 every year before winter started. I disconnected the hoses at the water pump and with a garden hose tried to force the water back through. If you want to do a quick check, with the car warmed up, grab each heater hose and if one is hot and the other is not, then their is no flow through the heater core.