coolant leak

2003 CHEVROLET SILVERADO
250,000 MILES • 5.3L • V8 • 2WD • AUTOMATIC
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HAWGHEAD10
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for one, my heat does not blow warm at all. i have a coolant leak somewhere between the engine and radiator up top, but have not located yet until morning. my heater fan works fine on all 4 levels. i'm not sure yet if it's the blower motor resistor, thermostat, heater core or whatever else that makes the heater not even warm. it obviously has to do with the coolant leak so i'm thinking the heater core? (also not sure if its related but A/C does not blow cold and when i tried to recharge with A/C Pro Refrigerant the gauge went straight to the red zone after maybe 6 or 7 seconds) If unrelated just disregard A/C part. Thanks
Oct 10, 2020 at 7:27 PM
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ASEMASTER6371
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Good morning,

The first thing I would do is pressure test the cooling system to locate the source of the leak. You can rent a tester at a parts store. Once we know the location, we can help you with the repair.

https://www.2carpros.com/articles/radiator-pressure-test

https://www.2carpros.com/articles/car-is-leaking-coolant

As far as the heat, it will not work correctly if the level is low. When it gets below the level of the heater core, it will not produce heat. If it was the heater core, you would have coolant leaking inside the truck on the passenger floor.

https://www.2carpros.com/articles/how-a-car-heater-works

https://www.2carpros.com/articles/replace-heater-core

Another possibility for no heat is a blend door actuator. If it is not moving the door to give full heat, this will result. It is also tied to the A/C operation as well.

https://www.2carpros.com/articles/replace-blend-door-motor

Roy

REMOVAL PROCEDURE
1. Remove the IP insulator.


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2. Disconnect the electrical connector (8) from the air temperature actuator (9).


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3. Remove the air temperature actuator retaining screws.


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4. Remove the air temperature actuator.
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Oct 11, 2020 at 4:23 AM
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HAWGHEAD10
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i found the coolant leak and it turned out that the water pump was bad so i replaced it. however, it did not fix my heat problem. now it will blow barely lukewarm. coolant is at correct level with no air bubbles. thermostat is also in good condition. my next attempt is the Blend Door Actuator. Do you think the Blower Motor Resister could possibly be the cause for no heat?
Oct 11, 2020 at 7:40 PM
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ASEMASTER6371
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Okay, before you go to the blend door, I would flush the heater core. Remove both hoses from the firewall and use a garden hose and run the water through the core. Run it both ways until you get a good even flow and clear water.

Try that before you do the blend door.

As far as the resistor, no, it only controls fan speeds, not heat.

Roy
Oct 12, 2020 at 4:21 AM