A/C Stops and starts intermittantly
05-17-2017, 06:48 AM
#1
A/C Stops and starts intermittantly
The other day the AC was working fine and then suddenly shut off. Another time it wouldn't come on and after 2hrs of driving it suddenly came on for the remaining 2hrs of the 4hr drive. A recharge seemed unlikely since it started working fine after not working, but maybe that's a telltale sign I don't know about. So, I ran a scan and am seeing the following. Does anyone have any experience with the symptom or with the faults found below?
I then did some tests on N280 A/C Compressor Regulator Valve thinking that might be the issue, but I didn't see anything alarming with the following results:
Code:
-------------------------------------------------------------------------------
Address 08: Auto HVAC (J255) Labels: Redir Fail!
Part No SW: 8T1 820 043 AA HW: 8T1 820 043 AA
Component: KLIMA 1 ZONE H06 0140
Revision: A1000000 Serial number: 0106.10.080892
Coding: 64002000
Shop #: WSC 06335 000 00000
VCID: 70E848EFA3B0B4BEAD-8024
2 Faults Found:
01273 - Fresh Air Blower (V2)
009 - Open or Short to Ground
Freeze Frame:
Fault Status: 01101001
Fault Priority: 3
Fault Frequency: 80
Reset counter: 18
Mileage: 162410 km
Time Indication: 0
Date: 2017.01.26
Time: 10:01:47
Freeze Frame:
Temperature: 9.0°C
Speed: 0.0 km/h
Voltage: 0.00 V
Current: 0.000 A
Voltage: 12.40 V
01844 - Control Module for Fresh Air Blower (J126)
014 - Defective - Intermittent
Freeze Frame:
Fault Status: 00101110
Fault Priority: 3
Fault Frequency: 41
Reset counter: 49
Mileage: 162410 km
Time Indication: 0
Date: 2017.01.26
Time: 10:01:47
Freeze Frame:
Temperature: 9.0°C
I then did some tests on N280 A/C Compressor Regulator Valve thinking that might be the issue, but I didn't see anything alarming with the following results:
Last edited by 4lane; 05-17-2017 at 01:54 PM.
05-18-2017, 01:34 PM
#2
Just an update, I'm thinking the problem is one of two issues:
1) Compressor Regulating Valve (N280) faulty
- this can be related to the intermittent fault I'm getting under: 00898 - Control Circuit A/C Compressor
2) Refrigerant is low
3) Failing A/C Pressure/Temperature Sensor (G395)
- I have not seen a fault code for this, but it seems to be a common issue
Any guesses on which of the three, considering it blows cold sometime, but doesn't work other times while the A/C light is always on (never turns off unexpectedly)?
1) Compressor Regulating Valve (N280) faulty
- this can be related to the intermittent fault I'm getting under: 00898 - Control Circuit A/C Compressor
2) Refrigerant is low
3) Failing A/C Pressure/Temperature Sensor (G395)
- I have not seen a fault code for this, but it seems to be a common issue
Any guesses on which of the three, considering it blows cold sometime, but doesn't work other times while the A/C light is always on (never turns off unexpectedly)?
Last edited by 4lane; 05-18-2017 at 02:36 PM.
05-20-2017, 07:09 PM
#3
Last night I ran some more tests. At the time the A/C was working fine. Going through all the tests for flaps/motors seemed to work fine. I cleared this code and ran it for a bit without the code being thrown. I turned the car off/on, ran the tests again and saw this fault thrown again. But the A/C still worked fine. I was kinda hoping to see it stop when the fault was thrown, pointed to N280. Any thoughts and/or what abnormal N280 output tests should look like?
Code:
00898 - Control Circuit A/C compressor
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 6
Fault Frequency: 1
Reset counter: 58
Mileage: 162410 km
Time Indication: 0
Date: 2017.01.26
Time: 10:01:47
05-22-2017, 06:06 AM
#4
Another clue to the puzzle: during the times when the A/C is not working, I've noticed that no fans are on to try and cool things down either. I would expect that if the a/c was just not operating, that the rest of the system (blowers, etc.) would be active. Is this true and could this point to something that controls the climate in general? As in, it's not reading the temperature correctly, or is just not operating to be able to read the temp and kick in the a/c, blowers, etc?
Code:
01844 - Control Module for Fresh Air Blower (J126)
014 - Defective - Intermittent
Freeze Frame:
Fault Status: 00101110
Fault Priority: 3
Fault Frequency: 41
Reset counter: 49
Mileage: 162410 km
Time Indication: 0
Date: 2017.01.26
Time: 10:01:47
Freeze Frame:
Temperature: 9.0°C
05-22-2017, 08:48 AM
#5
TPI 2033596/3
Looking at the common issues across the three faults, I see the ones in blue and red below. I wish I could find more info on "TPI 2033596/3". There's nothing that I've been able to find...
Code:
00898 - Control Circuit A/C Compressor: Open or Short to Plus Possible Symptoms * Climate Control not working Possible Causes Fuse(s) faulty * Wiring and/or Connector(s) from/to Compressor Regulating Valve (N280) faulty * Compressor Regulating Valve (N280) faulty * Heating/Climate Control Module (J301) faulty 01273 - Fresh Air Blower (V2) Possible Causes * Fresh Air Blower (V2) defectivea * Control Module for Fresh Air Blower (J126) defective * Short of open circuit in wiring to Fresh Air Blower (V2) * Climatronic Control Module (J255) malfunctioning Special Notes * When found in Audi A4/A5/Q5 (8K/8T/8R) models: North American Market (NAR) vehicles, see TPI 2033596/3 (or newer) 01844 - Control Module for Fresh Air Blower (J126) Possible Causes * Control Module for Fresh Air Blower (J126) defective * Fresh Air Blower (V2) defective * Short or open circuit in wiring to Control Module for Fresh Air Blower (J126) * Climatronic Control Module (J255) malfunctioning Special Notes * When found in Audi A4/A5/Q5 (8K/8T/8R) models: North American Market (NAR) vehicles, see TPI 2033596/3 (or newer)
I am not sure about your fans, but sometimes that is the resistor for the blower motor. I have one for sale, if it turns out to be that. I had an issue with my G395 recently, in which the wiring had been pinched. The sensor is just behind the grille on the driver's side, so I suggest double checking the wiring before anything else. My AC wouldn't blow cold at this time, but once the wiring was spliced and reconnected, I am all set.
Last edited by 4lane; 05-22-2017 at 09:35 AM.
05-29-2017, 03:26 AM
#7
Im leaning in that direction too because it seems like the compressor is running, just no cold air is coming inside.
Is their a way to test and isolate the issue down to the blower? I assume this blower just blows a/c into the cabin. Does it also blow hot air (as in can I turn the heat on and expect no hot air to blow in the cabin when not working)? Or what does it actually do?
Is their a way to test and isolate the issue down to the blower? I assume this blower just blows a/c into the cabin. Does it also blow hot air (as in can I turn the heat on and expect no hot air to blow in the cabin when not working)? Or what does it actually do?
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05-29-2017, 10:00 AM
#8
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Im leaning in that direction too because it seems like the compressor is running, just no cold air is coming inside.
Is their a way to test and isolate the issue down to the blower? I assume this blower just blows a/c into the cabin. Does it also blow hot air (as in can I turn the heat on and expect no hot air to blow in the cabin when not working)? Or what does it actually do?
Is their a way to test and isolate the issue down to the blower? I assume this blower just blows a/c into the cabin. Does it also blow hot air (as in can I turn the heat on and expect no hot air to blow in the cabin when not working)? Or what does it actually do?
Your B8 A4 climate control module J255 communicates with blower control module J126 through LIN bus. J126 activates blower motor and speed depended on request from Climate control module J255.
When blower motor is not blowing when requested, you can check its motor coil resistant. You can also disconnect blower motor connector and plug in a heavy load light bulb (I use a halogen headlight bulb). If the light bulb is On and its brightness changes when you vary blower speed, you can say the motor is faulty.
There are many production running changes since 2009, you might want to call your local Audi dealer to get correct updated parts. I would replace both blower motor and control module J126.
05-30-2017, 12:26 PM
#9
The only thing that doesn't make sense is when it's not working I can turn the fan up all the way. I would expect it not to blow if it won't blow cool air in the cabin.
However, based on this diagnosis, it does sound like both the blower/control module should be replaced: http://ricksfreeautorepairadvice.com...r-doesnt-work/
I'm going to pull it out and see if I can test it as you suggested and also clean it up. I've read that the carbon brush dust can cause intermittent issues that a good cleaning will fix.
However, based on this diagnosis, it does sound like both the blower/control module should be replaced: http://ricksfreeautorepairadvice.com...r-doesnt-work/
I'm going to pull it out and see if I can test it as you suggested and also clean it up. I've read that the carbon brush dust can cause intermittent issues that a good cleaning will fix.
In your car ( similar to most vehicle), blower motor assembly is designed to blow air into passenger compartment. Air can be cooled down or heated up when blowed through either evaporator or heater core or both.
Your B8 A4 climate control module J255 communicates with blower control module J126 through LIN bus. J126 activates blower motor and speed depended on request from Climate control module J255.
When blower motor is not blowing when requested, you can check its motor coil resistant. You can also disconnect blower motor connector and plug in a heavy load light bulb (I use a halogen headlight bulb). If the light bulb is On and its brightness changes when you vary blower speed, you can say the motor is faulty.
There are many production running changes since 2009, you might want to call your local Audi dealer to get correct updated parts. I would replace both blower motor and control module J126.
Your B8 A4 climate control module J255 communicates with blower control module J126 through LIN bus. J126 activates blower motor and speed depended on request from Climate control module J255.
When blower motor is not blowing when requested, you can check its motor coil resistant. You can also disconnect blower motor connector and plug in a heavy load light bulb (I use a halogen headlight bulb). If the light bulb is On and its brightness changes when you vary blower speed, you can say the motor is faulty.
There are many production running changes since 2009, you might want to call your local Audi dealer to get correct updated parts. I would replace both blower motor and control module J126.
05-30-2017, 08:28 PM
#10
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Your car might have two separate problems. One is no air flow because of faulty blower motor and/or blower control module. Other problem is having air flow but not cold because of problem in refrigerant system (compressor, pressure sensor, condenser, cooling fans, etc). Try to fix one problem first. I would do the blower motor and control module now then recheck.