These quick, simple tasks can help prevent coming home to a disaster.Reasons for car heater to not blow hot air? September 24, 2009   Subscribe Need help from mechanics! Asking for a friend: On a 2005 Mercury Marquis, the air temperature control does not work. What could be the cause and possible ways to fix it?Air Conditioning (A/C) Evaporator Discharge Air Temperature Sensor Ford Fusion owners: Beware if your A/C has stopped working! Ford had a genius idea to install a sensor in the top of the evaporator case. What does this mean to the owners of the Fusion? I should start by saying there are many reasons why your car's A/C can stop working. But on the Fusion, if the A/C compressor is not turning on, you will need to change the Evaporator Discharge Air Temperature Sensor. The sensor tells the computer what the air's temperature is at the exit point of the evaporator. When it senses that it's cold, it turns off the compressor. Otherwise, the system would freeze. Well, sometimes these sensors short out and will not allow compressor operation.

Ford is well aware that the sensors are faulty. So I suggest that if your Fusion has low miles and is out of warranty, you contact Ford and demand they repair it. I have changed the sensor on cars as low as 22,000 miles (but it was over three years old). The problem is that you must remove the entire dashboard to change this part and there is no way around it. The total labor for this job is 6.7 hrs, and the part costs $17.49. Depending on your area, the average price for the job would be around $600 + tax. I do it for $500 out the door. I have heard of people paying in excess of $800! If you are the do-it-yourself kind of person, I will attach the instructions on changing the sensor yourself below. Remove the instrument panel. Detach the A/C evaporator discharge air temperature sensor. Disconnect the sensor's electrical connector. To install, reverse the removal procedure. INSTRUMENT PANEL REMOVALRemoval and Installation CAUTION: Electronic modules are sensitive to static electrical charges.

If exposed to these charges, damage may result. Depower the supplemental restraint system (SRS). Remove the floor console. Remove the LH and RH instrument panel end trim panels. Remove the weather striping from the front door openings near the instrument panel. Remove the A-pillar trim panels.how big ac unit needed Remove the RH and LH cowl kick panels.ac and heater not working From behind the LH kick panel, disconnect the two electrical connectors.my central ac unit is not cooling 8. From behind the RH kick panel, disconnect the bulkhead electrical connector and the antenna lead-in cable. CAUTION: To avoid damage to the bulkhead electrical connector, be sure the release handle is in the full UPWARD position before disconnecting the electrical connector.

9. From underneath the glove box, disconnect the three A/C electrical connectors. 10. Disconnect the electrical connector and retainer located on the floor between the two front seats. 11. NOTE: To make sure of proper location during installation, index-mark the position of the steering column shaft before removing the pinch bolt. Remove the steering column pinch bolt. 12. Remove the instrument cluster finish panel. 13. Remove the instrument cluster. Remove the 2 screws. Remove the instrument cluster. Disconnect the electrical connector. 1. Remove the two instrument panel center brace bolts. To install, tighten to 20 Nm (15 lb-ft). 2. From through the instrument cluster opening, remove the two instrument cluster opening bolts. 3. Remove the two instrument panel lower bolts. To install, tighten to 8 Nm (71 lb-in). 4. Remove the instrument panel. CAUTION: To avoid damage to the instrument panel, this next step requires the help of an assistant.

Remove the three instrument panel cowl side upper bolts. To install, tighten to 23 Nm (17 lb-ft). CAUTION: To avoid an improper connection at the bulkhead electrical connector, be sure to position the connector for installation then push the release handle to the full DOWNWARD position until it clicks. To install, reverse the removal procedure. She lives in a small, simple house in southern Mississippi. It's only 1700 square feet. Why then, she wondered, were her summer electricity bills running more than $600? She didn't have anything that could be a big energy hog, like a swimming pool, and she didn't do stupid things like leave all the doors and windows open while she ran the air conditioner. What could it be? She called her electric company, one of the co-ops in Mississippi, and they sent someone out to investigate. Utility companies get calls like this all the time, and they've learned from experience what most of the main causes of high bills are. When the utility investigator arrived arrived at the house, he asked her to tell him anything she knew that might help him.

"Well," she said, "the air conditioner runs all the time, but the house won't even cool down to 80 degrees." "Ah, that helps to narrow it down a bit." He went to work, and it didn't take him long to find the problem. He measured the temperature drop across the air conditioner coil and found that the air on the 'cool' side wasn't much lower than the air on the warm side. And both were much warmer than they should be. OK, that could be a disconnected duct in the attic, he thought, like the one from a different house that you see above. A look in the attic, however, showed that wasn't the case here. Besides, a disconnected duct would increase the bill, but it almost certainly wouldn't quadruple it. His next step was to turn off the breaker to the electric resistance heat (a.k.a. strip heat) in the HVAC system. This is basically a giant toaster inside the air handler. Heat pumps use it for supplemental heat. In some homes, it's used as the primary heat source. It's not cheap, though, especially considering that the same electricity going into a heat pump will yield two or three times more heat.

Anyway, the utility investigator turned off the breaker to the strip heat and watched what happened to the meter. In the summer time, turning off the strip heat should have no effect at all on how fast the meter spins because it shouldn't be running. Strip heat is for cold weather. In this case, the meter went from spinning fast enough to saw wood to moving as slow as a horned passalus (photo at right) going for a walk in the woods. "Well, we found your problem, ma'am," he told her. "Your heating and cooling system was doing both at the same time, making you spend a lot of money to stay uncomfortable." This problem often results from a thermostat wired incorrectly so that the system kicks on the strip heat when it shouldn't. Since anyone can go down to the home improvement store or the Interwebs and buy a thermostat, a good number of these problems result from DIY jobs. It seems crazy to think that someone wouldn't notice that the heat is running in their home in summer, but they don't feel heat coming out of the vents.