1993 Volvo 850 climate control device

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  • 1993 VOLVO 850

Heater problem
1993 Volvo 850 Front Wheel Drive Automatic 150000 miles

My 5 cylinder Volvo 850 GLT has no control of cabin temperature. There is no control of the damper doors directing the airflow. Is the A/C programmer broken and can it be repaired?

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Wednesday, March 4th, 2009 AT 6:07 PM

1 Reply

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Hi ttuffin,

Here is a description of the temperature controls and how to retrieve Diagnostic Trouble Codes.

The Electronic Climate Control (ECC) control module can detect faults in the system and store Diagnostic Trouble Codes (DTC). If a fault is present, system informs driver by flashing the LEDs by the AC and REC switches for 20 seconds. A fault warning is given when a fault is discovered or present, each time ignition is turned on, or engine started. DTCs will remain stored until cleared by an input code.

NOTE: Test Unit (981 3190) and Adapter (981 3194) are required for DTC diagnosis. The Volvo Diagnostic Key (998 8670) may be used to perform self-diagnostics. Follow tool manufacturer's instructions.

There are 3 different test modes/settings which can be selected for reading off DTCs. TEST MODE 1 may be used for reading off DTCs detected by control unit (up to 47 codes can be stored). TEST MODE 2 checks signals from speedometer and solar sensor.

TEST MODE 4 is used to check electrical circuits in A/C system, reset information on damper motor limit positions and change data transmission speed from ECC control module to on-board diagnostic unit.

NOTE: Ignition must be turned off before switching from one test mode to another.

1. Connect selector cable from diagnostic unit "A" to terminal No. 1 of diagnostic unit "B", located behind right headlight. See Fig. 2 .


2. Turn ignition on. LED on diagnostic unit "A" should start flashing. Each DTC (3-digits) consists of a series of flashes with a short break between each series. DTCs are displayed in ascending order.

1. Turn ignition on. Press button on diagnostic unit "A" for about one second. Read LED flashes.

2. If LED flashes DTC 1-1-1, no faults are stored. If LED flashes other than DTC 1-1-1, display DTCs and perform appropriate DTC trouble shooting.

1. Turn ignition on. Press button on diagnostic unit "A" twice (for about one second each time). LED should start flashing rapidly once TEST MODE 2 is activated.

2. If LED flashes DTC 1-1-2, signal from solar sensor is okay. If LED flashes DTC 1-1-3, signal from speedometer is okay. If neither DTC is present, go to next step.

3. If DTC 1-1-2 is not present, check solar sensor. If DTC 1-1-3 is not present, check speed sensor signal. To exit TEST MODE 2, turn ignition off.

1. Turn ignition on. Press button on diagnostic unit "A" 4 times (for about one second each time). LED should illuminate. If LED illuminates, go to next step.

2. Control codes must be entered one step at a time. See TEST MODE 4 CONTROL CODES . LED should go off after each digit is entered. Entering each digit in a code must be made within 4 seconds as failure to do so will abort input and TEST MODE 4 must be restarted.


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Saturday, March 7th, 2009 AT 2:21 PM

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