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Old 07-10-2013, 10:58 AM   #1 (permalink)
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Default Fluctuating A/C Temp

So this is the second summer I've had my '09 Outback. I bought it used from a Subaru dealer in May 2012 with about 38k miles on it. So far, everything has been great, except one minor annoyance.

When it is hot out, the A/C puts out air that fluctuates in temperature. When you first turn it on, it gets quite cold. It then will moderate to a more "cool" temperature before getting almost not even cool, at which point it will suddenly get cold again. It does the cycle probably every minute or so. At this point, it is mostly an annoyance as it puts out plenty of cold/cool air to cool down the cabin. It is really only noticeable if you actually are feeling the air coming out of the vents. I often have the upper vents blowing on my hands, so I feel it a lot. It does not seem to matter the engine running or driving conditions (town, highway, idle, higher rpm, etc.).

When I bought the car, the dealer gave me a 3 month/3,000 mile bumper-to-bumper warranty that they give with all of their used car purchases. I had them look at it last summer, and they recharged the system and said it was a little low but they found no leaks. Subsequent visits yielded no apparent problems. Since then, I have kind of forgotten about it as it got into the colder seasons, but now I am reminded of it again this summer.

Any ideas what might be up with it before I go spend money to have my mechanic tell me nothing's wrong with it?
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Old 07-10-2013, 09:50 PM   #2 (permalink)
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Two things:

Too much or too little. Too much=overcharged; the refrigerant can't circulate properly to absorb the heat from the passenger compartment. Too little=leak or it was undercharged to begin with.
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Old 07-11-2013, 06:50 AM   #3 (permalink)
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^^^ most often that.

Does the 2009 "Special Edition" have the automatic HVAC controls (dial in temperature and it takes care of the rest) or is it the manual controls? The automatic is known to vary the air flow and operation in strange ways -- there are threads about it here.

Another possible cause of compressor cycling could be potential icing at the evaporator due to restricted air flow. If it hasn't already been done, check the cabin air filter to make sure it's not clogged.

Reduced air flow can cause the temperature at the evaporator to get too low. If it nears the freezing point, the evaporator thermal switch signals the ECM, and the compressor is turned off in order to avoid a buildup of ice on the evaporator. (An evaporator coated with ice can't absorb heat from the air passing over it.) Then, when the temperature is back to an acceptable point, the compressor is re-activated. This could lead to a fairly steady on/off cycling.
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Old 07-11-2013, 07:09 AM   #4 (permalink)
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Also, check if any of the drainage of condensation moisture/water is free and open so that the water properly drains out.
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Old 07-11-2013, 10:21 AM   #5 (permalink)
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Quote:
Originally Posted by plain OM View Post
Does the 2009 "Special Edition" have the automatic HVAC controls (dial in temperature and it takes care of the rest) or is it the manual controls?
The 2009 SE has manual controls, so no problem there.

I'll try checking the cabin air filter to see if that works.

As far as checking the refrigerant, I'm guessing I'll need to have my mechanic look at it. I am a novice so I don't want to mess anything up.
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Old 07-11-2013, 10:54 AM   #6 (permalink)
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You know, my car is doing the same thing. It has the digital climate control. I had the A/C checked for leaks and refrigerant and the car was cleared. It was suggested that possibly the condenser could use a "rinsing or cleaning". I also changed my cabin filter(existing was pretty dirty). Zero change...although I did get some interestingly colored water off the condenser. I'm inclined to go back to a different shop and have it checked w/Cardoc's video in hand and watch them and make sure.
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Old 07-11-2013, 11:01 AM   #7 (permalink)
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Try one of these....

FJC 5914 Foaming Evaporator Cleaner : Amazon.com : Automotive FJC 5914 Foaming Evaporator Cleaner : Amazon.com : Automotive
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Old 07-11-2013, 04:11 PM   #8 (permalink)
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I also have a 2009 Outback with "compressor cycling" going on. I am orig owner and have owned car since Aug 2008, so this is the 6th Summer for the A/C system. Car has 60k and the A/C system has worked flawlessly every year but has just recently started compressor cycling. System has never been serviced in any way.

Cabin filter was just changed and there is always a nice puddle of water under the car after use of A/C. No one has mentioned this so I'll ask: Can I just get a can of refrigerant from Pep Boys and top off the charge myself? Used to do this on my old cars. Is this possible on 09 Outback and is there any reason why this would be a bad idea?
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Old 07-11-2013, 04:52 PM   #9 (permalink)
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Have an 09 that cycled the AC. The dealer found the freon level low and adjusted the level. So far, the system no longer cycles.

However, I cannot say that I am satisfied with the ability of the AC to cool the car when the outside temperatures are approaching triple digits.
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Old 07-11-2013, 09:58 PM   #10 (permalink)
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Quote:
Originally Posted by polara View Post
I also have a 2009 Outback with "compressor cycling" going on. I am orig owner and have owned car since Aug 2008, so this is the 6th Summer for the A/C system. Car has 60k and the A/C system has worked flawlessly every year but has just recently started compressor cycling. System has never been serviced in any way.

Cabin filter was just changed and there is always a nice puddle of water under the car after use of A/C. No one has mentioned this so I'll ask: Can I just get a can of refrigerant from Pep Boys and top off the charge myself? Used to do this on my old cars. Is this possible on 09 Outback and is there any reason why this would be a bad idea?
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Originally Posted by ths258 View Post
Have an 09 that cycled the AC. The dealer found the freon level low and adjusted the level. So far, the system no longer cycles.

However, I cannot say that I am satisfied with the ability of the AC to cool the car when the outside temperatures are approaching triple digits.
If the refrigerant is low, there is a leak. If the leak is not found and repaired, the level will drop again. How fast it drops depends on the leak.

Places that just "adjust the level" are only taking your money and not repairing the problem. Then when it starts doing it again they want to sell you an AC system.

Find the leak.
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