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I. Silva
I. Silva, ASE Certified Technician
Category: Subaru
Satisfied Customers: 1603
Experience:  auto mechanic
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My 2002 sub forester makes a gh pitched sucking/ guppy sound

Customer Question

my 2002 sub forester makes a high pitched sucking/ guppy sound when the AC or defroster is turned on? Any thoughts on what it could be? There is some green discharge/ colorant on the (what I think is) the receiver/ dryer. Is that supposed to be there or is that a sign of a leak?
Also pulling a PO442 small evap leak code? Could the two be connected?
I had a smoke test done at the dealer and they could not find any leaks.
Submitted: 1 year ago.
Category: Subaru
Expert:  I. Silva replied 1 year ago.

Hello...welcome and thank you for using Justanswer.

The greenish color you see is from an ac system leak ,his is Freon most likely with dye that we usually use to check for leaks with special light (uv light)

I would check the AC system performance ,make sure the pressures are good (low pressure around 35/45 and the high pressure close to 200 psi,depending on the temperature where you are)

The code P0442 it is for a small evap leak detected , I don't know what did they smoke on the system ,beside the fuel tank ,canister and the hoses/lines ,there are also the purge and vent valves that need to be tested for proper operation ,they need to open and closed when commanded by the engine computer when running the test on the evap.

One of the most common small leaks is the fuel tank cap ,you can just buy it and have the code erased then drive the vehicle to see if the problem is solved.

Other possible causes are the hoses at the fuel tank neck ,evap canister or the hoses to it ,fuel pump gasket or a rusty fuel tank but to check this you will need the smoke machine.

Good luck.

Let me know.

Thank you.

Customer: replied 1 year ago.
it sounds like I need to take the car in and have the AC system checked - am I right?
As for the PO442 - I replaced the fuel cap - as the dealer suggested after the smoke test and it was not the issue.
Customer: replied 1 year ago.
would the two issues be related? would the AC leak cause the PO442 code?
Expert:  I. Silva replied 1 year ago.

Yes ,correct I would have the system checked for proper pressures and performance of the AC compressor to find out if the noise and the leak are affecting the system.

About the code P442 ,you may have to go back to the shop and have them checking for leaks with the smoke machine and also to check the purge and vent valves ,I usually check the leaks not just with the smoke machine but also using a bottle of water and soap on the most common places and check for bubbles once the smoke machine pressurizes the system.

Good luck.

Let me know and please rate my answer if I have helped.

Thank you very much.

Expert:  I. Silva replied 1 year ago.

No ,the two problems are not related.