Air Conditioner sometimes blows hot air once engine has warmed up

Probably have a bad Door Airflow control box

im not sure what fails here.
no air, from all vents. no cold air , no hot air.
tell me what you want.? hot or cold air. (or defrost)
does the blower blow on high?
did you check all fuses. 1st.
if real serious. on DIY repairs, try the FSM.
or a great subs. alldata.com

As per your problem mentioned.There are few solved help links to troubleshoot these problems.Go through the list and Click the link below:----
Air conditioner blows air but not cold air http://repairhelpcenter.blogspot.in/2012/07/air-conditioner-blows-air-but-not-cold.html

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Car overheats and Air blows hot at idle? http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

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Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html

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Heat blows cold on drivers side and hot on passenger side? http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html---------- Hot air on the driver's side vents only? http://repairhelpcenter.blogspot.com/2012/01/hot-air-on-drivers-side-vents-only.html

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2005 Chrysler PT Cruiser: A/C Blows Warm? http://whoisbyme.blogspot.in/2012/06/2005-chrysler-pt-cruiser-ac-blows-warm.html

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1992 Toyota Camry: A/C Control light Flashing and A/C not Blowing Cold? http://technoanswers.blogspot.in/2012/04/1992-toyota-camry-ac-control-light.html

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No heat, blower blows only cold? http://technoanswers.blogspot.in/2012/02/no-heatblower-blows-only-cold.html

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These will help.
Thanks.

Check whether the warm air isn't going in with the cold air .Coolant line that runs into the firewall on the passenger side of the engine which is toward the bottom half of the firewall on the passenger side. If there is warm air going into the vents with the cold air then it blows warm air. You may have to shut it manually because it gets stuck sometime. Check it out.

Could be a list of things including low on freon, low pressure switch, relay, or the a/c clutch on the compressor.

check your blower motor under the passenger side of the dash, round plastic box three screws pull it out something might have fallen though your cowl and chewed up the fan blades. as for the ac your r-12 is probly empty or has a leak bring it to a local garage and have them flush and fill your cooling system. heater would be your thermostat not openig properly, by far your cheapest fix under ten dollar part.

#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.

there can be a problem to air conditioner of the car . I guess you just have to go to the dealer or the toyota car shop for repair of the air conditioner . may be it's the fan of the air con that is not working properly. they can replace it .Because it is design to that car .

hello,seem you need to send your car to authorized dealer to scan the problem,maybe the solution is only synchronizing all the flap,ty

check too se if cooling fan is operating