RCX Ambient Temperature Sensor module - Meade RCX400 12 Telescope

Did you by chance check for DTC'S diagnostic trouble codes?

Instrument Cluster Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1255 Air Temperature External Sensor Circuit Open Instrument cluster Go To Pinpoint Test E . B1257 Air Temperature External Sensor Circuit Short to Ground Instrument cluster Go To Pinpoint Test E . B2097 Compass Module Failure Instrument cluster Go To Pinpoint Test B . U2013 Compass Module - No Response Instrument cluster Go To Pinpoint Test B . All Other DTCs - Instrument cluster REFER to Section 419-10 .

It looks like the ambient air temperature sensor and that's the way some of them are, if you can see where it broke off super glue it back on. The engine control module uses ambient air temperature signal to adjust fuel mixture.

031 B1251 IN-CAR TEMPERATURE SENSOR OPEN GO to Pinpoint Test B
PINPOINT TEST B: IN-CAR TEMPERATURE SENSOR INOPERATIVE B1 CHECK SENSOR RESISTANCE

NOTE: An open sensor will cause warm air discharge at 18°F (65° C) setting. A shorted sensor will cause cool discharge air at 29°F (85°C) setting.

• Disconnect the A/C ambient air temperature sensor.
• Using an ohmmeter, measure the resistance across the sensor terminals and compare the readings with the following sensor resistance table:
  
  Approximate Temperature Sensor Resistance Acceptance Range 10-20°C (50-68°F) 37K-58K ohms 20-30°C (68-86°F) 24K- 37K ohms 30-40°C (86-104°F) 16K-24K ohms

Are resistance values within the specified limits?
Yes No GO to B2 . REPLACE A/C ambient air temperature sensor and bracket. RESTORE vehicle. RETEST system. B2 CHECK ASPIRATOR INSTALLATION

• Gain access to automatic temperature control sensor.
• Check for proper installation of automatic temperature control sensor hose and elbow.

Is aspirator installed properly and hose connected?
Yes No GO to B3 . SERVICE automatic temperature control sensor hose and elbow as necessary. RESTORE vehicle. RETEST system. B3 CHECK CIRCUIT 470 (PK/BK) AT AUTOMATIC TEMPERATURE CONTROL SENSOR

• Turn ignition switch to the RUN position.
• Turn EATC module to NORM A/C position.
• Disconnect automatic temperature control sensor.
• Using a voltmeter, check Circuit 470 (PK/BK) for voltage at sensor connector.

Is voltage 5 volts?
Yes No GO to B5 . GO to B4 . B4 CHECK CIRCUIT 470 (PK/BK) FOR OPEN

• Disconnect connector C227 at EATC module.
• Using an ohmmeter, check Circuit 470 (PK/BK) between EATC module and automatic temperature control sensor for open.

Is there 5 ohms or less?
Yes No SERVICE Circuit 470 (PK/BK) for open. RETEST system. GO to B5 . B5 TEST CIRCUIT 470 (PK/BK) FOR SHORT

• Using an ohmmeter connected to a good ground, connect other lead to EATC module connector Pin C227 , Circuit 470 (PK/BK).

Is resistance less than 10,000 ohms?
Yes No SERVICE Circuit 470 (PK/BK) for short. RESTORE vehicle. RETEST system. GO to B6 . B6 TEST CIRCUIT 790 (W/O) FOR OPEN

• Using an ohmmeter, connect one lead to EATC module connector Pin C227 , Circuit 790 (W/O) and other lead to automatic temperature control sensor Circuit 790 (W/O).

Is resistance 5 ohms or less?
Yes No GO to B7 . SERVICE Circuit 790 (W/O). B7 TEST CIRCUIT 790 (W/O) FOR SHORT

• Using an ohmmeter connected to a good ground, connect other lead to EATC module connector Pin C227 , Circuit 790 (W/O).

Is resistance less than 10,000 ohms?
Yes No SERVICE Circuit 790 (W/O) for short. RESTORE vehicle. RETEST system. REPLACE EATC module. RESTORE vehicle. RETEST system.

No. . The temperature you set controls the module. When the inside sensor sees that temperature the fan speed slows and the blend door responds to that temperature.

Manual or automatic climate control ?
Have you had the HVAC control panel checked for DTC'S - diagnostic trouble codes ?

Air Temperature Sensors
The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:
• Ambient Air Temperature Sensor
• Inside Air Temperature Sensor Assembly
• Upper Left Air Temperature Sensor
• Upper Right Air Temperature Sensor
• Lower Left Air Temperature Sensor
• Lower Right Air Temperature Sensor
A signal and a low-reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40°C (-40°F) to 101°C (215°F). The sensor signal varies between 0-5 volts.
The input of the duct air temperature sensors are different from the ambient and inside sensors. The HVAC control module converts the signal to a range between 0-255 counts. As the air temperature increases the count value will decrease.

• DTC B0174 Output Air Temperature Sensor (Upper Left) Circuit Range/Performance
• DTC B0179 Output Air Temperature Sensor 2 (Lower Left) Circuit Range/Performance
• B0414 is for the left air temperature actuator.
B0408 is for the left air temperature actuator.
DTC B0989 Output Air Temperature Lower Sensors Correlation
The HVAC control module monitors the upper left and upper right duct temperature sensors when the mode switch is in the VENT or BI-LEVEL positions. The HVAC control module monitors the lower left and lower right duct temperature sensors when the mode switch is in the DEFOG, FLOOR or FRONT DEFROST positions. The duct sensors are used to measure the temperature of the air exiting the ducts to help maintain a consistent cabin air temperature. These duct sensor inputs provide the HVAC control module a way to determine if the engine needs to be started to maintain a specific air temperature. If an upper duct sensor circuit failure is detected the HVAC module will not request an engine start to help cool the cabin. A lower duct sensor circuit failure will not prevent the engine from starting.
DTC B0990 Output Air Temperature Upper Sensors Correlation
Your best bet , take it to a qualified repair shop .

E5 on Freezer Display Ambient temperature sensor error Unplug the refrigerator and check the wiring connections in the ambient temperature sensor circuit. If the wiring connections are okay, replace the ambient temperature sensor. If the problem persists, replace the electronic control board. Ambient temperature sensor, Electronic control board

P0072 - Ambient Air Temperature Sensor Circuit Low Input

- Faulty ambient air temperature sensor
- Ambient air temperature sensor harness is open or shorted
- Ambient air temperature sensor circuit poor electrical connection

- Faulty ambient air temperature sensor
- Ambient air temperature sensor harness is open or shorted
- Ambient air temperature sensor circuit poor electrical connection

A educated guess I would have to say there is a problem with HVAC control module ! electronics you know ! But that's not the way to do things ! There could be codes stored in the module. The Chevy dealer my have a reflash bulletin for this problem . Then can reflash , reprogram the control module ! The first place to start is checking for codes in the HVAC module.
The HVAC control module is a class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, all HVAC DTCs and settings will be erased from KAM. The body control module (BCM), which is the vehicle mode master, provides a device on signal.
Air Temperature Sensors The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors:
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Ambient Air Temperature Sensor

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Inside Air Temperature Sensor Assembly

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Inside Air Temperature Sensor Assembly-Auxiliary

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Upper Left Air Temperature Sensor

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Upper Right Air Temperature Sensor

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Lower Left Air Temperature Sensor

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Lower Right Air Temperature Sensor

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Upper Air Temperature Sensor-Auxiliary

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Lower Air Temperature Sensor-Auxiliary
A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40?° to +101?°C (-40?° to +215?°F). The sensor signal varies between 0-5 volts.
The input of the duct air temperature sensors are different from the ambient and inside air temperature sensors. The HVAC control module converts the signal to a range between 0-255 counts. As the air temperature increases the count value will decrease.
If the HVAC control module or auxiliary HVAC control module detects a malfunctioning sensor, then the control module software will use a defaulted air temperature value. The default value for the ambient and inside air temperature sensors will be displayed on the scan tool. The default value for the duct air temperature sensors will not be displayed on the scan tool. The scan tool parameter for the duct air temperature sensors are the actual state of the signal circuit. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.
The ambient air temperature sensor mounts underhood and can be affected by city traffic, by idling, and by restarting a hot engine. Therefore, the HVAC control module filters the value of the ambient air temperature sensor for temperature display. The ambient air temperature value is updated under the following conditions: Or you can just buy a new control module an hope that it fixes it. $89.00 at www.partsgeek.com

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The ambient temperature sensor going bad causes this exact problem. I've replaced many of them because when they show outside temp as being below 60 degrees, the A/C control module will shut the compressor off.