1989 Mercury Marquis NO HEAT IN PASSENGER CABIN

1989 MERCURY MARQUIS
11,000 MILES • V8 • 2WD • AUTOMATIC
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CWISENER
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  • 1 POST
STATUS: CLIMATE CONTROL SYSTEM PROVIDING 0% HEATED AIR TO PASS. CABIN.TEMP. ** CLIMATE CONTROL SYSTEM STATUS***> TEMP CONTROL VALVE - OK, (2)HEATER CORE WATER LINES ARE WARM AT BOTH INLET/OUTLET CONNECTIONS,(3) SERVO MOTOR OPERATING ACCESS DOORS AS DESIGNED. (4) TEMP CONTROL CABLE IS CONNECTED AND OPERATIONAL (5) VENT AIR DIST. POINTS ARE ALL OPERATING CORRECTLY My Question is: WHAT COULD PREVENT HEATED AIR FROM HEATER CORE COMPARTMENT REACHING THE AUTO CLIMATE CONTROL SYSTEM FOR DISTRIBUTION INTO PASSENGER CABIN? I HAVE EXUASTED ANY ADDTL. OPTIONS FOR REPAIR DOCS., MANUALS AND SELF HELP RESOURCES. **************PLEASE REPLY WITH ANY DIAGNOSES,SOULTIONS, DIAGRAMS, TROUBLESHOOTING PROCEDURES, AND POSSIBLE FAUTLY PART DESCP./ PART# ETC. (DESPERATE IN DALLAS) {chris wisener} cwisener@msn.com (972)836-2768
Jan 31, 2010 at 6:29 PM
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MERLIN2021
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Heater Core — Plugged

WARNING: The heater core inlet hose will become too hot to handle if the system is working correctly.

Check to see that the engine coolant is at the correct level.
Start the engine and turn on the heater.
When the engine coolant reaches operating temperature, feel the heater core inlet and outlet hose to see if they are hot.
If the inlet hose is not hot:

the thermostat is not working correctly.
If the outlet hose is not hot:

the heater core may have an air pocket.
the heater core may be restricted or plugged.
If both are hot, the temperature blend door in the heater plenum may be broken or stuck...
Jan 31, 2010 at 6:50 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.