Ford Country Squire Ambient Air Temperature Sensor Guide (1987-1991)
If your wagon's automatic climate control is acting up, the small ambient air temperature sensor could be the reason.
- This sensor's main job is for the automatic climate control system, not the engine.
- Symptoms are almost always related to the A/C and heat, such as the 'Auto' mode not working or an incorrect temperature display.
- Replacement is very easy and located behind the front grille, making it a great DIY task.
- Aftermarket brands offer a reliable and cost-effective solution; an OEM part is not necessary for this component.
Understanding the Ambient Air Temperature Sensor on Your Wagon
The ambient air temperature (AAT) sensor on the 1987-1991 Ford Country Squire is a simple but important part for wagons equipped with Electronic Automatic Temperature Control (EATC). It's a type of resistor called a thermistor, which changes its electrical resistance based on the temperature. The EATC computer reads this change and knows how hot or cold it is outside. This allows the 'Auto' function on your climate control to work properly, managing the A/C and heat to maintain the temperature you've selected. It is not a common failure point, but when it does go bad, it can make your climate control system seem confused.
Symptoms of a Bad Ambient Air Temperature Sensor
A failing AAT sensor on this generation of Country Squire will primarily affect the automatic functions of your HVAC system. You will likely notice one or more of the following issues:
- Inaccurate Outside Temperature Display: If your wagon has a digital display for the outside temperature (in an overhead console, for example), it may show readings that are obviously wrong, such as showing 30°F on a hot summer day.
- Automatic Climate Control Not Working: The 'Auto' setting on your EATC may not function correctly. The system might not be able to maintain a consistent temperature, or the fan speed might not adjust as expected.
- A/C Compressor Won't Engage: The EATC may prevent the A/C compressor from turning on if it receives a faulty low-temperature signal from the sensor, even on a hot day. This means you'll only get warm or hot air from the vents when you expect cold air.
- Heating and Cooling is Erratic: The system might blow hot air when it should be cooling, or vice-versa, as it struggles to regulate the cabin temperature with bad data.
Cost of a New Aftermarket Ambient Air Temperature Sensor (1987-1991)
| Brand Tier | Our Price Range | Notes |
|---|---|---|
| Premium Aftermarket (e.g., Standard Ignition) | $25 - $36 | Brands with a long history of supplying quality electronic components. Often considered an OE-equivalent. |
| Standard Aftermarket (e.g., Holstein, True Tech) | $12 - $25 | Meets basic fit and function requirements. A cost-effective choice for a simple sensor like this. |
Choosing the Right Aftermarket Brand
For a simple sensor like the AAT, an OEM part from a dealer is often unnecessary and costly. Aftermarket brands provide a reliable and affordable alternative. The technology for this sensor is basic, and manufacturing quality is generally consistent among reputable brands.
- Standard Ignition: A well-regarded brand in the industry, known for producing parts that meet or exceed original equipment specifications. A solid choice for reliability.
- Holstein: Offers a range of sensors that are a direct fit. They provide a good balance of quality and value.
- True Tech: Positioned as a value-oriented brand, offering a functional replacement at an accessible price point.
Pro Tip: Given the low cost and simple design of this part, any of the available aftermarket brands should provide a reliable fix. The key is ensuring the part number is correct for your vehicle year. There is little practical difference in performance between the brand tiers for this specific component.
Installation
Replacing the AAT sensor is a straightforward job that most owners can do themselves in under 30 minutes with basic tools.
- Locate the Sensor: The sensor is typically located in front of the radiator and A/C condenser, mounted behind the front grille. You may need to look through the grille slots or from underneath the front bumper to see it. It's a small, black plastic probe with a two-wire electrical connector.
- Disconnect the Sensor: Carefully unplug the electrical connector. There may be a small tab you need to press to release it.
- Remove the Old Sensor: The sensor is usually held in place by a plastic clip or a single small screw. Unclip it or unscrew it and remove it from its mounting bracket.
- Install the New Sensor: Snap or screw the new sensor into place. Reconnect the electrical harness. The climate control system should now receive the correct outside temperature reading.
Frequently Asked Questions (FAQ)
Will a bad ambient air sensor turn on the Check Engine Light?
It is unlikely on this specific vehicle. The AAT sensor on the 1987-1991 Country Squire primarily serves the climate control system, not the engine management system. While newer cars may trigger a Check Engine Light with codes like P0070-P0074, these older Fords typically will not for this particular sensor.
Can I just ignore a bad ambient air temperature sensor?
Yes, you can. A bad sensor will not prevent the car from running safely. However, the automatic functions of your climate control will not work correctly, and you may not be able to use your air conditioning. You will have to manage the heat and A/C manually, if the system allows.
Is there a difference between the ambient air temp sensor and the air charge temp sensor?
Yes, they are two different sensors with different jobs. The Ambient Air Temperature sensor measures outside air for the climate control. The Air Charge Temperature (ACT) sensor measures the temperature of the air going into the engine for the fuel injection computer (EEC-IV).
Why is my temperature display stuck at a weird number?
When the sensor fails or the circuit is broken, the computer may show a default reading. This is often a very low number, like -40 degrees. This is a clear sign that the sensor or its wiring has failed.
Technical Specifications
OEM Part Numbers: E7VY-12A647-A F3VY-12A647-A AE5Z-12A647-A
2-pin thermistor sensor
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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