Forum Discussion

TurnThePage's avatar
TurnThePage
Explorer
Nov 23, 2021

Ambient Temp Sensor Troubleshooting

Right up front, this is not an RV related question, but I know there's tremendous vehicle knowledge and experience to be had here.

We have a 2012 Ford Fusion that doesn't know the outside temperature and thus is unable to heat/cool the inside properly. The temp display will sometimes be accurate briefly, but will soon start drifting downward, eventually bottoming out way below zero, before wandering back upward some. It goes all over the place. Internet research indicated that I should replace the ambient temp sensor, which I did, twice. The sensor I replaced is behind the front bumper and fascia. Is there another sensor? Could a bad fuse cause that behavior? I'm getting ready to remove it all together to see if there's any difference.
Tow Vehicles
  • TurnThePage's avatar
    TurnThePage
    Explorer
    Nov 28, 2021
    Grit dog wrote:
    Lol. No mechanic work in the winter?
    Damned straight!

    My garage is too small to close the doors and have room to work, and I don't need the A/C just yet. Besides, it's my wife's car. :B
  • TurnThePage's avatar
    TurnThePage
    Explorer
    Nov 26, 2021
    Thanks for the research and feedback. Those items are the cabin air temp sensors.

    Just to be clear, we're talking about the ambient temp sensor that displays the outside temp and provides input to the HVAC system.
  • TurnThePage's avatar
    TurnThePage
    Explorer
    Nov 26, 2021
    So... I've learned that there is only one sensor and it's the one I changed. I've also learned that it's semi-common for the wiring to this sensor to get damaged if there is even minor front damage. When this happened, my wife had hit a snow berm.

    Also, this sensor absolutely does influence the HVAC system. In the winter it's not too bad, you can always get heat, usually too much, but you can deal with that by cracking a window.

    Shouldn't be too difficult to find the damaged wiring once I get going on it, likely next spring.
  • jfritz_drfritz's avatar
    jfritz_drfritz
    Explorer
    Nov 25, 2021
    If I understand this correctly you have two problems. The first is that the outside temperature does not display correctly. I would agree that this is likely related to the ambient temperature sensor in front. However, there is almost certainly a separate sensor that measures the interior car temperature. Fixing the outside temp sensor probably would not fix the HVAC problem. Just my opinion I don't know for sure
  • dodge_guy's avatar
    dodge_guy
    Explorer II
    Nov 24, 2021
    Some cars have 2 sensors, one behind the grille and the other in an outside door mounted mirror.
  • ae5573t's avatar
    ae5573t
    Explorer
    Nov 23, 2021
    I had a similar problem and like you I replaced the ambient temperature sensor. It didn't fix the problem. I had to replace the ambient temperature sensor connector. That is what fixed my problem.
  • enblethen's avatar
    enblethen
    Nomad
    Nov 23, 2021
    There should be two. You replaced the one for the engine control and not the heating/cooling system.
    My Chrysler has the passenger comparment sensor internal to the temperature control unit.

About Travel Trailer Group

44,025 PostsLatest Activity: Feb 18, 2025