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05 Impreza AC cycles on and goes PSSST #4390748
04/27/17 08:43 PM
04/27/17 08:43 PM
Joined: Apr 2012
Posts: 88
MD, USA
jeffie7 Offline OP
jeffie7  Offline OP
Joined: Apr 2012
Posts: 88
MD, USA
2005 Subaru Impreza with about 95K miles on it. When the AC is on, it cycles on and off every 30 seconds or so, when it cycles on it sounds almost like a blow off valve PPSSST

AC works fine, blows very cold. What would cause the compressor to make a PSSST sound?

Other than the pssst sound, the car's AC feels great.

Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4390760
04/27/17 08:54 PM
04/27/17 08:54 PM
Joined: Dec 2006
Posts: 70
saginaw michigan
saginawmale50 Offline
saginawmale50  Offline
Joined: Dec 2006
Posts: 70
saginaw michigan
It sounds like the compressor clutch is cycling off and on. Most likely your compressor is near end of life.

Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4390897
04/28/17 12:16 AM
04/28/17 12:16 AM
Joined: Aug 2010
Posts: 12,903
Northern Kentucky
901Memphis Offline
901Memphis  Offline
Joined: Aug 2010
Posts: 12,903
Northern Kentucky
AC issues usually require a mechanic, no not usually DIY unless you have the equipment if you want it done right.


2012 Chevy Cruze LT 1.4T - 50k
2002 Buick Century 130k - Built 4T65e(Maxlife) - Edge 0w40 + Fram XG3980
Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4390935
04/28/17 03:50 AM
04/28/17 03:50 AM
Joined: Nov 2006
Posts: 19,900
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 19,900
MA, Mittelfranken.de
On Subaru Vehicles compressor cycling is normal operation, as long as its cold and not cycling every 5 seconds there is no problem. Cycling times will vary with ambient air temp.

Edit: I don't know if this normal on the latest models as I have little experience with them.

Last edited by Trav; 04/28/17 03:52 AM.

ASE L1, Master. Deutsch Meisterbrief.
Re: 05 Impreza AC cycles on and goes PSSST [Re: 901Memphis] #4390982
04/28/17 06:17 AM
04/28/17 06:17 AM
Joined: Apr 2012
Posts: 88
MD, USA
jeffie7 Offline OP
jeffie7  Offline OP
Joined: Apr 2012
Posts: 88
MD, USA
Everything works fine. The question at hand is if this is a sign of something. I've only had the car for about 10k miles and the AC rarely used. Now that my wife is driving it and the kids can finally go in it, the ac is always on, which is why I noticed it. Might be nothing. As AC systems tend to cycle often to keep from freezing. It's just weird to me that it goes psst.

Not planning on taking it in to a shop unless there's reason to believe something could be wrong. Just trying to get some opinions from anyone they might know AC systems.

Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4390990
04/28/17 06:23 AM
04/28/17 06:23 AM
Joined: Nov 2006
Posts: 19,900
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 19,900
MA, Mittelfranken.de
If its cold I wouldn't worry about it, these Subaru's have all sort of little quirks and engine noises that on another engine would mean impending certain doom but on these its normal e.g what sounds like a rod knock at idle (it isn't).
Do watch out for head gasket issues, very easy job on these but a common failure point.


ASE L1, Master. Deutsch Meisterbrief.
Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4391034
04/28/17 07:28 AM
04/28/17 07:28 AM
Joined: Mar 2010
Posts: 5,356
Iowa
The_Eric Offline
The_Eric  Offline
Joined: Mar 2010
Posts: 5,356
Iowa
Cycling is normal as mentioned, but maybe the clutch plate is dragging for a few moments once the clutch cycles off? That would account for the noise you had mentioned. If so, it's likely a sign that the A/C clutch springs are getting weak and the will start dragging all of the time when the A/C compressor is not engaged.


2005 Lincoln Aviator 4.6 DOHC
2000 Honda Accord 2.3
2001 Hyundai Elantra 2.0
1979 Ford F-150 351M
Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4391046
04/28/17 07:38 AM
04/28/17 07:38 AM
Joined: Feb 2009
Posts: 3,653
down in the park
Jetronic Offline
Jetronic  Offline
Joined: Feb 2009
Posts: 3,653
down in the park
Originally Posted By: jeffie7
2005 Subaru Impreza with about 95K miles on it. When the AC is on, it cycles on and off every 30 seconds or so, when it cycles on it sounds almost like a blow off valve PPSSST

AC works fine, blows very cold. What would cause the compressor to make a PSSST sound?

Other than the pssst sound, the car's AC feels great.



If you hear that inside the car, you're low on charge. The compressed and condensed coolant is already vaporizing before it reaches the evaporator.

If you hear it under the hood, I don't know what you're hearing exactly, but I suppose the low charge could be heard there aswell.


AR Giulietta 2.0 JTDM-2 -- Total Quartz 9000 Energy 0w30
Hankook Ventus Prime 2 215/50R17 (front)
Pirelli P7 Cinturato 225/45R17 (rear)
Re: 05 Impreza AC cycles on and goes PSSST [Re: Jetronic] #4391278
04/28/17 11:27 AM
04/28/17 11:27 AM
Joined: Apr 2013
Posts: 2,326
The Northeast
mclasser Offline
mclasser  Offline
Joined: Apr 2013
Posts: 2,326
The Northeast
Originally Posted By: Jetronic
If you hear that inside the car, you're low on charge. The compressed and condensed coolant is already vaporizing before it reaches the evaporator.

I'm no A/C expert but my Accord made a psssst noise from the A/C as well. It was inside the cabin and seemed to coincide with the compressor cycling. After I topped off the system (was a little low), the noise almost disappeared; only hear it now on the hottest days when idling.


2018 Hyundai Elantra VE -- 4K
2013 Honda Pilot EX-L 4WD -- 56K
2002 Honda Accord EX-L -- 211K

Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4391327
04/28/17 12:34 PM
04/28/17 12:34 PM
Joined: Aug 2010
Posts: 12,903
Northern Kentucky
901Memphis Offline
901Memphis  Offline
Joined: Aug 2010
Posts: 12,903
Northern Kentucky
Eric the car guy has a nice AC condenser cleaning video which shows how much internal pressure changes when you clean the condenser even if the interior temps aren't affected much. It will cycle less with a fully cleaned system


2012 Chevy Cruze LT 1.4T - 50k
2002 Buick Century 130k - Built 4T65e(Maxlife) - Edge 0w40 + Fram XG3980
Re: 05 Impreza AC cycles on and goes PSSST [Re: 901Memphis] #4396149
05/04/17 10:57 AM
05/04/17 10:57 AM
Joined: Apr 2012
Posts: 88
MD, USA
jeffie7 Offline OP
jeffie7  Offline OP
Joined: Apr 2012
Posts: 88
MD, USA
Originally Posted By: 901Memphis
Eric the car guy has a nice AC condenser cleaning video which shows how much internal pressure changes when you clean the condenser even if the interior temps aren't affected much. It will cycle less with a fully cleaned system


Watched his video and ended up using this.

Simple Green Foaming Coil Cleaner.


[img]https://scontent-lga3-1.xx.fbcdn.net/v/t...amp;oe=59BE9D69[/img]

[img]https://scontent-lga3-1.xx.fbcdn.net/v/t...amp;oe=597FE901[/img]

[img]https://scontent-lga3-1.xx.fbcdn.net/v/t...amp;oe=59BE33A7[/img]


It still makes the Psssst noise but it's much much less noticeable and less frequent. When I get a chance I'm going to run up to the local AC shop and have the system checked to see if its over/under charged.

Regardless, clearly the cleaning helped.

Last edited by jeffie7; 05/04/17 11:01 AM.
Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4396552
05/04/17 08:36 PM
05/04/17 08:36 PM
Joined: May 2004
Posts: 2,489
Northeast
sxg6 Offline
sxg6  Offline
Joined: May 2004
Posts: 2,489
Northeast
I have a subaru too, a legacy, and from what I've heard they are super picky about how much refrigerant is in the system. If you take it to a shop, make sure they know subaru's and put the correct amount of refrigerant in.

I didn't have anyone touch the AC system in my '09 legacy until I hit around 200k and it seemed like my AC wasn't as cool as it should be. Had the dealer do an AC system service, and it was the same after. I think it was just the heatwave we had last summer, car just couldn't get the air as cold as I thought and would have liked.

Re: 05 Impreza AC cycles on and goes PSSST [Re: jeffie7] #4439989
06/23/17 11:33 PM
06/23/17 11:33 PM
Joined: Apr 2012
Posts: 88
MD, USA
jeffie7 Offline OP
jeffie7  Offline OP
Joined: Apr 2012
Posts: 88
MD, USA
Just wanted to give an update, I finally had a chance to take the car into the shop to have the AC system inspected. The system was low on refrigerant. After having the system recharged and dye added they ran the car for awhile and could not find any signs of a leak, I was asked to bring it back after a few weeks to recheck for the leak.

No more Psssst sound.


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