In the meantime, he's going to research replacement units for us and get us some proposals and pricing. One possibility would put in a separate unit for our upstairs, which might be a big improvement as far as our cooling bills go. We'll see.
He's also going to look in the attic and see if the cooling situation can be improved with an attic fan to vent the hot air out. But he'll do that on a cooler day than today. :)