How to do the self test on a Grand Marquis?
To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTOMATIC button within 2 seconds. The display will show a pulse tracer going around the center of the display window. The test may run as long as 30 seconds. Record all DTCs displayed.
How is the heat in a Grand Marquis controlled?
With the engine at full operating temperature, locate the two heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator.
How can I tell if my Grand Marquis has a leak?
If there is a leak, what you described is what happens. Check under the dash for disconnected, damaged, dry rotted, vacuum hoses as well as under the hood. If you are lucky, you will hear a hissing sound from the leak with the engine running.
Why is my Grand Marquis blowing hot air?
If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged.
To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTOMATIC button within 2 seconds. The display will show a pulse tracer going around the center of the display window. The test may run as long as 30 seconds. Record all DTCs displayed.
With the engine at full operating temperature, locate the two heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator.
If there is a leak, what you described is what happens. Check under the dash for disconnected, damaged, dry rotted, vacuum hoses as well as under the hood. If you are lucky, you will hear a hissing sound from the leak with the engine running.
If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged.