Air conditioner goes cool then warm then cool then warm

Here's a step by step check list of things that can cause an AC blows warm condition.

https://ricksfreeautorepairadvice.com/ac-blows-warm/

may have air trapped in it still or thermostat is not working properly..

One thing that affects both the cooling system and the a/c is the cooling fan.
Could be a bad fan motor or relay. Or a connector.

I had the same problem with my ford, it turned out to be a door in the dash that switched between heat and a/c, the clicking noise is the gears flaping the door but not being able to open, if your heat works fine but not a/c this is the problem. BTW this part is very hard to get to without removing your dash.

If after a few minutes it is still warm to hot air, try recharging the cooling system. Parts stores sell kits with instructions on how to do this.

#46-12-03: AIR CONDITIONER BLOWS WARM AIR (REPLACE A/C DELAY RELAY) - (Apr 7, 1994) REVISION: 04/14/94
THIS BULLETIN IS BEING REVISED TO CORRECT THE TRANSMISSION LISTED IN THE MODELS. ----------------------------------------------------------------------
SUBJECT: AIR CONDITIONER BLOWS WARM AIR (REPLACE A/C DELAY RELAY)
MODELS: 1994 CHEVROLET AND GMC TRUCK S/T PICKUP WITH 4.3 ENGINE (VIN Z - RPO LB4), 4L60E TRANSMISSION (M30) AND AIR CONDITIONER/MANUAL CONTROLS (C60); OR 4.3 ENGINE (VIN W - RPO L35) AND A/C (C60)
BUILT BEFORE THE FOLLOWING VIN BREAKPOINTS:
PLANT DIVISION VIN LINDEN GMC RK501034 SHREVEPORT GMC R8501199 SHREVEPORT CHEVROLET R8105893 LINDEN CHEVROLET RK103097
CONDITION:
SOME OWNERS MAY EXPERIENCE A CONDITION WHERE THE AIR CONDITIONER IS TURNED ON AND DELIVERS ONLY WARM AIR.
CAUSE:
THE AIR CONDITIONER COMPRESSOR MAY DELAY LONGER THAN THE "ORIGINAL DESIGN" INTENDED 12 SECONDS, OR MAY NOT ENGAGE, DUE TO THE POSSIBLE MALFUNCTION OF THE COMPRESSOR DELAY RELAY.
CORRECTION:
TRUCKS BUILT BEFORE THE VIN BREAKPOINTS LISTED ABOVE MAY NEED A NEW AIR CONDITIONER DELAY RELAY. REPLACE ONLY WITH 15990540 AIR CONDITIONER COMPRESSOR DELAY RELAY. SPECIFIED PROCEDURE IN SERVICE MANUAL NATP 9429, PAGE 1B-59. TEST AIR CONDITIONER OPERATION FOR DELIVERY OF COOL AIR.
NOTE:TO TEST FOR PROPER OPERATION, PUT THE A/C CONTROL ON THE "OFF" POSITION, START THE ENGINE, THEN PLACE THE A/C CONTROL IN THE "ON" POSITION. THIS SEQUENCE WILL PROVIDE IMMEDIATE ENGAGEMENT OF THE AIR CONDITIONER COMPRESSOR. WHEN THE ENGINE IS STARTED WITH THE A/C CONTROL ALREADY "ON", THERE WILL BE A NORMAL 15.0 SECOND DELAY FOR THE AIR CONDITIONER TO ENGAGE.
SERVICE PARTS INFORMATION:
P/N DESCRIPTION QTY
15990540 A/C COMPRESSOR DELAY RELAY 1
PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

will the fan run? Is the air warm, is there no air? it won't cool if the fan won't circulate air across the cooling coil. You may have a fan problem

2004 chevy Avalanches air conditioner blows hot air, can the actuator be forced to keep it blowing cold air instead of hot air all the time.

I have a feeling that no one is checking the blend door in the plenum.

check the refrigerant it might have 2 be recharged