2003 mercury sable blows cold, cold air when heater is turned on.
It won't be the thermostat...Sable and Taurus have a design problem. The heater core hose going into heater core from water pump gets plugged up right at the heater core bypass junction. At Hardware store..Buy hard plastic hose/tubing about 4ft long that just fits inside of the heater core hose. My ACE hardware has white hard tubing. Cut one end of the hard tubing at angle to use it as a reamer inside the heater core hose. Now place the hard tubing on top of heater hose to measure the distance on hard tubing it has to travel up to firewall . Mark with black marker on hard tubing. Remove the heater core hose from top of water pump and slide hard tubing in hose all the way up to where the bypass connection is feeling the obstruction...rotating the hard tubing as you gently shove it thru heater core hose. Slide it back and forth and keep rotating it until you feel it go past the Bypass junction...10 min at least. Now take off the heater hose from engine on driver side that comes from the heater exit side...Use garden hose high pressure and back flush the crud out. Re connect hoses, add fluid to reservoir as needed. Or take to shop and have them do this. Many shops just back flush...Have them do BOTH! Buy the plastic tubing ahead of time so they have no excuse. I have been doing this on my 98 Taurus since 1999. Done many of these...If you haven't changed thermostat for 4 years ...Change that as well. You tube has videos. Email me at [email protected] I promise you hot air...from the car!
Most likely it is a clogged heater core. Have your heater core reverse flushed or your blend door is stuck open.
SOURCE: heater doesn't work
Sounds like the heater core is stopped up. Try removing the heater hoses and backflushing the core.If this doesn't work replace the core.
SOURCE: 2002 mercury sable heater wont get hot
you have a broken or stuck temp blend door in the heater case. or the servo motor is broken. this sits on top of the heater case
SOURCE: mercury 2003 gand marquis heater
One of 2 things could be happening. #1, the valve that allows coolant to circulate thru the heater core is not functioning. #2 the door that is actuated to allow cabin air to circulate around the heater core is not functioning properly. Possible causes, linkage to the valve, or actuator not working. Also a broken valve to the heater core. A vacuum leak, or faulty actuator would cause the door not to function. You can narrow down the problem somewhat by making sure that both heater hoses have hot coolant in them. You can do this by simply feeling the hoses. If they are both circulating hot coolant, then the problem is the misdirection of air flow. To repair this, the cause will have to be diagnosed, could be anything from your dash mounted controls to an issue with vacuum or the ductwork or the door or actuator. If not in the controls, the dash may have to come out. Good Luck, I hope this is helpful!
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SOURCE: 2003 mercury grand marquis LS
The blend door is stuck in cold position. That usually happens because the blend door actuator has failed.
You will need to test and replace the blend door actuator.
To replace the actuator you will need to take apart the dash and remove completely the instrument panel,d isconnect the connector, remove the four screws, remove the temperature blend door actuator and replace it.
The replacement is not a job for beginners, since you have to take apart the dash to access the actuator.
Regards.
SOURCE: Heater in mercury marquis doesn't come on. Cold
Hello. The most common cause for no heat is the thermostat. This is a quick and easy repair. Go to any autozone or similar parts store for the part. They may even install it for you.
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