Broken Automatic Climate Control? - Subaru Outback - Subaru Outback Forums
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post #1 of 7 (permalink) Old 01-29-2013, 12:12 AM Thread Starter
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Broken Automatic Climate Control?

I took my 2002 VDC into a Car Toys to get a stereo installed. The first issue was plagued with the alternator issue that seems to be famous on these cars/amps. The second time, they screwed up the climate control. It either works at 84/85 or blows normal air. (seems like there's very little difference from 65-79 with 80-83 occasionally working). I can't seem to find anything on this forum but i did find this blog article: Will's semi-regular rant: Automatic Climate Control problems - Subaru Outback H6 2001-2004 models Does anyone have any idea of what they might be talking about? The only hose i can think of is the one attached to the heater control panel above the radio but the article kinda sounds like it might be a different one or the other end which im not sure where it'd be. They never posted any more pictures and that's about all i can find on the issue. I don't want to take it back to that place after they screwed up twice. :\

Thanks for any help. I sure do hate that damned amp and 13 pin cord for causing me all this trouble. :l

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post #2 of 7 (permalink) Old 01-29-2013, 07:43 AM
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Thats whyi never take any of my vehicles to car toys, they tend to mess up.

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post #3 of 7 (permalink) Old 01-29-2013, 10:00 AM
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There is a hose connected to the face plate of the HVAC control that leads to a temperature sensor under the dash. If its unplugged, the unit will get conflicting information. Also, if they inadvertently unplugged the sun load sensor in the dash, it will not operate. In removing the HVAC control unit, if they have something that is not plugged in tight, it will effect controls.

For the Aspirator tube:

SOURCE: Subaru Tech Tips

TITLE: Automatic A/C System Aspirator Tubes

APPLIES TO: All models with Auto A/C

SERVICE TIP:

Subaru has received some calls on vehicles equipped with the Automatic Climate Control system with the concern of the heater blowing cold air.

If you get such a concern, make certain the system's aspirator tube is properly connected and if so, also make sure it's not kinked or restricted by a harness or something else.

The vehicle's aspirator tube tells the system what the cabin temperature is. Without this input, it cannot adjust the system properly to maintain the correct temperature.

Also, be aware that this can cause the a/c system to not cool properly as well in warmer temperatures.

This tube should be inspected anytime you have a poor heating/cooling concern on these vehicles.



For General info:

SOURCE: Subaru Tech Tips

TITLE: H-6 Climate Control System Information

APPLIES TO: Legacy L.L.BeanVDC Outback


SERVICE TIP:

Both the Subaru Legacy L.L.Bean and VDC model Outback use the Valeo/Zexel Automatic Climate Control System. This system contains a few new circuits not found on any other Subaru A/C systems. The following is some information you may find useful.

The first new circuit is a new two-wire circuit that runs from the Engine Control Module (ECM) Connector B134, pin 13, to the rear of the A/C compressor connector F82, pin 2, then from the compressor to a vehicle ground at connector B83, pin 12. This circuit was originally thought to be a compressor thermal limiting device but, upon further inspection, it was found to be an internal compressor speed sensor. This is a "pulse" signal that is emitted 4 times per compressor revolution.

Upon closer inspection of this new circuit, it was found that the black (B) wire that exits the rear of the compressor is the ground-side of the circuit, which ends at the vehicle ground connector (B83). The second wire, which is yellow (Y) in color, comes out of the compressor and then changes to white (W) at the first connector on top of the compressor. This circuit continues to the ECM as the input side of the circuit to the module. By monitoring this wire with a Digital Volt Ohm Meter (DVOM) set to the AC volt setting, you can monitor the AC voltage being sent to the ECM.

The New Select Monitor (NSM) was installed and noted the following air conditioning monitors:A/C Switch ON/OFF (monitors driver input from a/c switch)
A/C LOCK SIGNAL ON/OFF (ECM lock out of compressor clutch engagement)
A/C MID PRESSURE ON/OFF (input of high pressure to ECM for fan control)
A/C COMP SIGNAL ON/OFF (command from ECM to energize a/c clutch)

Next the compressor speed signal circuit to the ECM was disabled and it was discovered that when a/c is requested through the switch by the driver, the compressor clutch engages for 5 seconds and then disengages for the remainder of the 'key ON' cycle. It was also noted that without the compressor speed signal input, the A/C LOCK SIGNAL changed from OFF to ON meaning the ECM had cancelled the compressor ON signal therefore disabling the compressor clutch.

Next 3 key ON/OFF cycles were performed, requesting a/c each time, with the speed circuit disabled followed by an ECM self test that revealed that no trouble codes were set due to the loss of this signal. This leads to the conclusion that failure of the internal speed sensor or an open anywhere in the circuit will render the a/c compressor inoperative. Again, by monitoring the A/C LOCK SIGNAL and the A/C COMP SIGNAL, using the select monitor, one can see if the ECM has locked out the compressor clutch circuit causing a no engagement concern.

The second circuit investigated was from the ECM connector B135/pin23 to the Dual Pressure Switch on the receiver drier connector B10/pin4/R wire. The Dual Pressure Switch continues to control the compressor clutch for high and low system pressure cutoff in the same manner as on previous systems. The fourth wire (red in color) is new to this vehicle application. It was noted that this new circuit uses a 5V reference signal from the ECM to the pressure switch, which can be monitored using a DVOM.

Monitoring this circuit with a DVOM and observing a/c system refrigerant pressures with service gauges revealed that the voltage changes from 5V to 0V at approximately 260PSI high side pressure reading. In conjunction with the circuit voltage change, it was noted that the ECM increased the engine cooling fan speed to combat the higher high side pressure. It was determined that this new circuit is for mid-pressure cooling fan control by the ECM, and again, a new feature to this vehicle. This circuit can be monitored using the Select Monitor A/C MID PRESSURE data reading.
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post #4 of 7 (permalink) Old 01-29-2013, 04:18 PM Thread Starter
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Thanks for the information, the manual and the haynes repair guide lack any information about this. I looked under the steering wheel and it looks like there's 2 plugs disconnected. I'll go plug those back in, but is the black tube (it looks like the one on the back of the heater / a/c control panel so i'm assuming it is) suppose to go to a little white thing that's open, or is there another hose that connects to the white thing? Is that the sensor?

edit: i plugged in the green colored plugs under the steering wheel and it gave a Check Engine Light. Errrr... There were two other white plugs that were disconnected, but they didnt go to anything? they looked like they might have been stereo related because it looks like they spliced those two.

more edits: i figured out the green plugs were for some test thing so it's not that. This post seems to have nearly the same problem but nobody answered it, i'm curious if it's suppose to be unattached on one end or not: https://www.subaruoutback.org/forums/...tion-tube.html
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post #5 of 7 (permalink) Old 01-30-2013, 02:20 PM
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The green plugs are for ROM access, ECM programming. The white two wire is for the same. Leave them alone.

The black tube is supposed to be connected to the back of the HVAC and a port at the bottom side of the HVAC driver's side.

I have never had issue with the automatic AC. Maybe I keep buying the oddballs.
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post #6 of 7 (permalink) Old 02-22-2019, 06:02 PM
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I came across this post when trying to troubleshoot my 2002 LL Bean Outback HVAC blower. The LL Bean trim has an ACCS. Fuses 1 & 2 were fine. Motor relay and transistor checked ok. I found constant line voltage at the motor lead wire, regardless of fan speed setting. Coincidentally, the seat heaters were also not working. Before going any further I pulled every fuse and found #4, the cig lighter and rear view mirror fuse, had blown. That was the problem. Nowhere - in online forums, YouTube, or even my Subaru mechanic - did anyone indicate that there’s any connection between these circuits. The assumption was always a failed blower motor, although on a working circuit the motor lead will show 10+ volts at high setting, and incrementally lower voltages at the other settings. The coincidental failure of seat heaters and blower motor are a clue that it’s the fuse, at least for the ACCS HVAC.
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post #7 of 7 (permalink) Old 02-23-2019, 11:05 AM
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@payloadops
There are a lot of "oddball" circuits in the car. For instance, if your key ever gets stuck in the ignition lock cylinder, change the horn fuse then check your horns for issues because when the horn fuse blows, one of the horns is bad. but it's like this because the ignition lock is connected to the horn circuit which ties in with the keyless module and alarm.

I have yet to find a complete wiring diagram that ties circuits together. I have seen a lot of wiring diagrams from Subaru that identify wire color incorrectly or has mismatched circuit directories. May be in the translation, who knows.
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