Have problem with air conditioning

[ron2368]

I have a 06 Legacy sedan that has very cold AC when it works. Yesterday when I first turned it on it was nice cold air but after a while it gets warm, if I turn the AC off then wait a bit when I hit ON I can hear a click every 10- 15 seconds which I assume is the compressor . Occasionally after turning it off the AC will come on like normal and be nice and cold but eventually the compressor must be turning off. I was looking to charge it a month ago but when I hooked up the recharge can it showed the pressure was normal and not to add to the system. Is there any way to diagnose this with my limited AC knowledge? Thank you.

[1 Lucky Texan]

there's likely 3-4 problems that might lead to this behavior - and I am certainly no expert.

 

when you say it seems to work after being off "for a bit" - would that be long enough for ice to melt if the coil were frozen-over?

 

has the cabin air filter been serviced?

 

any correlation with the problem showing-up when stopped or in extremely slow traffic?

 

any large amounts of red dust near the compressor?

 

if you have lost 'some' refrigerant, the pressure switch that is supposed to protect the system may be right at the edge of triggering - such that it is intermittent.

 

a pro can check things out with some gauges, vacuum the system and otherwise check for leaks and a proper charge. Some people have done well attacking a/c problems on their own so, you might read here; http://www.subaruoutback.org/forums/99-do-yourself-illustrated-guides/43428-diy-c-air-conditioning-leak-refrigerant-repair-5-less-15-minutes-less.html

[ron2368]

The cabin air filter has been changed but its been a while so I will check it.

 

Thank you thats a good start of things to check.

[Rooster2]

The gauge on a do-it-yourself can with a hose, and small gauge is often very inaccurate. I have often see the gauge show that pressure is in the blue zone on the gauge, but still find the system is low on refrigerant. If system turns on the compressor more like every 5-10 seconds, then that is an indication of low refrigerant in the system. If you sense something like that, then add just half a can of refrigerant. Then see how that makes the system work.

 

I have also seen where the A/C works well when first turned on, as you are now finding, but then not putting out cool air once the system is on for a while. That too, is an indication of low refrigerant level in the system. Another reason to add a half a can to see if that improves the cold air output over extended time.

[Fairtax4me]

The charge level could be a little low.

 

The low pressure side only tells half the story. To get an accurate idea of charge level you also need to see the high pressure side of the system.

You can tell much more about the charge level by only looking at the high pressure side, than you can by only looking at the low side.

 

The expansion valve will alter the valve opening based on temperature. Even if the charge is fairly low, the expansion valve will usually be able to regulate the low side pressure to hang around 25 psi, and the high side pressure may be as low as 150 psi, which is far too low.

When properly charged, high side pressure will be in the 200-225 range with outside temp around 85-90°F. Low side pressure will be around 25-30 psi, or a bit more if it's very hot out. This is with engine speed around 1500 rpm and held for a minute or so.

 

The low side may only be off 5 psi, and on the cheapo can guage you probably won't even be able to tell.

But a 75 psi difference on the high side makes it very obvious that the system is undercharged.

 

You can get a real r134a manifold set on amazon for under $40.

[Cougar]

You stated that the A/C seems to start up good and work well. If the clicking you are hearing is the circuit breaker for the clutch circuit of the compressor then I tend to think you have nothing wrong with the A/C refrigerant but there is a problem possibly with the windings for the clutch.