Tech came out to perform heating maintenance inspection. Tech tested the heating system: checked gas pressure, temperature, exhaust fan amperage test, blower motor amperage test, flame rectification sensor test, exhaust fan vacuum test Tech found the furnace approximately 20+ years old in poor condition. Tech performed maintenance inspection and found the exhaust motor is just able to satisfy the safety switch. The gas valve is a non-adjustable gas valve and is slightly over. Its gas rating as well as the high limit continuously pops on the furnace. Tech increased fan speed to high, and this just satisfies the high limit, preventing it from opening Tech inform clients and informed him the furnace is heating for now however we cannot say how much longer it will last tech made a few options. Client will wait for furnace to fail and then call us back.