Heater Core Problems

HEATER CORE PROBLEMS



Leaking Heater Core - Leaks generally develop in one of two places:
1. Heater Hose Flanges - The tubing flanges to which the heater hoses are connected are soldered onto the heater core. When removing the hoses from the heater core excessive pressure may crack the solder joint, resulting in a leak.
2. Coolant tubes - Corrosion or an over pressure condition ruptures the tubing.

CAUTION: When replacing heater hoses, always twist the hose loose prior to pulling the hose off. If the hose will not slide off easily it should be cut off.

Plugged Heater Core - The coolant passages in the heater core are relatively small and may become easily blocked with corrosion, sediment, or silicone sealant.

SYMPTOMS
Leaking Heater Core
- Coolant is observed leaking from the vehicle near the back of the engine on the right hand side.
- The windshield is fogged up when the defroster is turned on.
- There is a distinctively sweet smell of coolant coming from the heater vents within the vehicle.

Plugged Heater Core - Heater will not produce warm air.

HOW TO VERIFY
Leaking Heater Core
- Pressurize the cooling system.



- Safely lift and support the vehicle. Examine the heater core drain tube for signs of coolant leakage.



NOTE: This is a small black tube coming out of the bottom of the fire wall in the engine compartment. This tube is designed to drain condensation from the A/C system and prevent leaking coolant from spilling onto the carpeting.

CAUTION: Do not confuse normal condensation leakage for coolant leakage.

- Examine the carpeting in front of the passengers seat for signs of coolant.

If coolant is found in either of the two places the heater core should be removed and inspected.

Plugged Heater Core
With The Engine Warm:
- Turn the heater on "HOT" and turn the fan on "HIGH" speed.
- Verify that there is a temperature difference between the two heater hoses. The inlet hose should be warmer than the outlet hose.

WARNING: Use a surface thermometer or infrared temperature gun to determine hose temperature. Do not attempt the feel the temperature by hand, this may result in serious personal injury.

With The Engine Cold:
- If a heater control valve is located in the coolant hoses, remove and test the valve prior to replacing the heater core.
- Test the heater core for restrictions:
- Remove the heater hoses from the heater core.
- Using regulated air pressure (less than 6 psi), blow air through the inlet to the heater core.
- If air does not pass freely, the core is plugged.



WARNING: Wear safety glasses and stand away from the heater core when performing this test. Coolant and sediment may be expelled with great force from the heater core outlet.


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