DTC B2979 or DTC indicator E and Windshield Defrost: An Open in the A/C Pressure Sensor Circuit

WARNING: This page is about a different car, the 2011 Acura TL, 2010 Acura TL, and 2009 Acura TL. However, it is still accessible from the selected car via links, so may be relevant.

Clear the DTC with the HDS
Turn the ignition switch to LOCK (0) and then back to ON (II), or press the engine start/stop button to select the OFF mode and then the ON mode
Do the self-diagnostic with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS ) or the climate control unit (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS )
Check for DTCs
Is DTC B2979 or E and WINDSHIELD DEFROST indicated?

YES -Go to step 5

NO -Intermittent failure Check for loose wires or poor connections on the A/C pressure sensor circuit
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode
Disconnect the A/C pressure sensor 3P connector
Disconnect climate control unit connector C (20P)
Check for continuity between the following terminals of climate control unit connector C (20P) and the A/C pressure sensor 3P connector
20P 3P

No 1 No 3

No 2 No 1

No 11 No 2

Fig 1: Checking Continuity Between Terminals Of Climate Control Unit Connector C (20P) And A/C Pressure Sensor 3P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 9

NO -Repair open in the wire(s) between the climate control unit and the A/C pressure sensor
Reconnect climate control unit connector C (20P)
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode
Measure the voltage between climate control unit connector C (20P) terminals No 1 and No 2, and between climate control unit connector C (20P) terminals No 1 and No 11

Fig 2: Measuring Voltage Between Climate Control Unit Connector C (20P) Terminals 1 And 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 5 V?

YES -Replace the A/C pressure sensor

NO -Check for loose wires or poor connections at climate control unit connector C (20P) and at the A/C pressure sensor 3P connector If the connections are good, substitute a known-good climate control unit, and recheck If the symptom/indication goes away, replace the original climate control unit (see Climate Control Unit Removal/Installation )