intermittent AC problem

[bgambino]

so my 2006 forster non turbo occasionally will stop blowing cold air....for say 2-4 minutes....whether driving or idling--does not matter

Smells humid when it does this...perhaps that's normal

 

I have noticed that the compressor is not spinning (when this happens at idle)

 

It blows plenty cold when it's running correctly so it cannot need freon

What else could it be? I'm afraid to ask...LOL

 

If guessing...I think this has been happening on the hottest days

 

Any help would be appreciated

thanks

 

[golucky66]

Could be a switch. Maybe the A/C switch is sticking or just wearing out to the point where it will occasionally tell the computer that you don't want A/C.

Could be a failing relay for the A/C clutch. 

 

Two things off the top of my head. 

Only real way to find the issue is when the A/C stops working, get out and search for an electrical issue. (sounds like an electrical issue not a mechanical one)

[Fairtax4me]

The evaporator core is freezing up and the thermo-sensor on the core is turning the compressor off. Then it takes those couple 30-45 seconds for the core to defrost. Once defrosted the compressor is allowed to turn back on and it starts the freeze cycle over again. 

 

Probably could use a small amount of refrigerant added to it. 

The newer systems only hold about 18oz, so its probably 3-4 oz low. 

[somick]

Depending on engine load the ECU will cut off the AC use.  At least that what my 2010 Forester owner manual say.

 

Good luck,

Sam

[ferret]

Probably a worn A/C clutch. You can check and adjust the gap, but here's a post I made a few years back: reply #11

 

http://www.ultimatesubaru.org/forum/topic/98733-2003-legacy-h6-intermittent-ac-issue/?p=832091

[Rooster2]

The evaporator core is freezing up and the thermo-sensor on the core is turning the compressor off. Then it takes those couple 30-45 seconds for the core to defrost. Once defrosted the compressor is allowed to turn back on and it starts the freeze cycle over again. 

 

Probably could use a small amount of refrigerant added to it. 

The newer systems only hold about 18oz, so its probably 3-4 oz low. 

+1 on what is written above. I have had that happen, and remember how the A/C would work, then evap core would freeze up. Like said, pretty certain that adding some refrigerant will fix this problem.

[1 Lucky Texan]

wouldn't hurt to check the cabin air filter - reduced air flow will exacerbate any freezing problem.

[bgambino]

wouldn't hurt to check the cabin air filter - reduced air flow will exacerbate any freezing problem.

Great thought LT

I did when I first had the issue...the filter was pretty nasty.....I forgot there even was a cabin filter

I thought the issue went away but has returned

Filter was just replaced 5-6 weeks ago so it can't be that now

 

I guess putting a shot of freon is doable....its just that it seems plenty cold

 

The thing about the condensor freezing might bi it....I wonder if that is visible at all to the naked eye

[1 Lucky Texan]

TOO cold is the problem - often can happen if low on refrig. (in homes too), there's a faster/stronger phase-change because - uh - the low-side pressure is too low (I guess?) and the coil will be cold enough to freeze moisture from the air passing thru it.

[idosubaru]

It blows plenty cold when it's running correctly so it cannot need freon

What else could it be? I'm afraid to ask...LOL

 

it can need freon, that's a classic low refrigerant symptom.  the system requires specific fluid properties at various points of the system - sensors turn it off if the fluid gets out of a range .

 

or a warn clutch - but the predictable nature of it points heavily towards freon. 

 

if it's low this also means it's slowly leaking - often from the orings at the compressor or schrader valves or hoses at the compressor.  all easy and cheap to replace. 

it's possible for it get worse or stay the same for the next 6 years and just need randomly topped off.