What could be restricting the air flow from the air conditioning on a 1997 K1500

Check the heater core it has a leak in it. Is the radiator losing antifreeze or a small amount at a time. Then it would be the heater core if no other leaks are showing.

Check to see if your heater hoses are hot when engine is at normal operating temp. (180 to 220 degrees F) If they don't get hot like the large radiater hoses do, then your heater hoses are clogged, probably at the point they connect to engine. Remove heater hoses from engine and I bet you will see dirt, grime, and corrosion where you took them off, restricting the flow of coolent through your heater core.

THIS ISSUE HAS BEEN SEEN WITH A BAD MASS AIR FLOW SENSOR AND OVER OILED K&N FILTERS CAUSING MAF SENSOR PROBLEMS. TRY CLEANING MAF WITH MAF CLEANING SOLVENT AND LET IT DRY BEFORE REINSTALLING. HOPE THIS HELPS

No Cabin air filter in a K1500 1997 Chevy. It is not standard equipment for this year.

could be a blend door problem or a restriction in the evaporator

Take the mass air flow sensor off and clean the small thin wires inside with a non-chlronated brake cleaner then let dry for 10 minutes then re-install.

may need to replace the mass air flow sensor as well as the catalytic converters.

check your owners manual and see if you have an inside cab air filter for the heater/air cond. When they get clogged, they restrict the air flow.

I had a similiar problem with my 1997 GMC 1500. The engine would sometimes even die while I was driving it. It turned out to be the sending unit (in the fuel tank). I replaced that about 2 years ago, and no trouble since.