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AC Hissing

michael.williams1

michael.williams1

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I've noticed the the AC in my 987.2 produces a slight hiss in the cabin (sounds like it's coming through the face vents) when the blower motor is on quite low and the temperature is set to maximum cold. When I turn the blower up the hiss diminishes. The AC seems to cool the cabin quite well. Is a hiss a characteristic of the Porsche system or does it indicate that something is starting to fail somewhere(?).
 
Personally I don’t recognise that phenomenon on my 987.3 CS Michael, but then I just leave my cabin temperature set to about 20 degC and let the climate control sort it out. Maybe the sound of the blower motor is drowning-out the hiss? It’s very noisy when on full blast!

If you can hear the hiss when outside the car there could be a leak in the system.

Jeff
 
Motorhead said:
Personally I don’t recognise that phenomenon on my 987.3 CS Michael, but then I just leave my cabin temperature set to about 20 degC and let the climate control sort it out. Maybe the sound of the blower motor is drowning-out the hiss? It’s very noisy when on full blast!

If you can hear the hiss when outside the car there could be a leak in the system.

Jeff
Click to expand...
Thanks Jeff. No I can't hear any hiss when I'm outside the car so I don't think it's a leak, it definitely puts out ice cold air and there's condensation water dripping under the car after a run, so everything seems to be working ... Google AI tells me "a slight hissing sound can be normal as the expansion valve regulates the refrigerant flow". Maybe that's what I can hear(?). Anyhow, the AC will likely get a good test on my road trip through Spain and France in a few weeks, so I'll see how it does!
 
Ian’s suggestion certainly is a possibility. You should be able to access the fan by removing the cabin filter [I’ve done this on a friend’s 981, but it should be similar for the 987]. If it is the fan you’ll hear it better, as well as being able to make sure that it’s spinning freely.

Enjoy your Euro trip, and I hope that the Cayman behaves itself.

Jeff
 
Motorhead said:
Ian’s suggestion certainly is a possibility. You should be able to access the fan by removing the cabin filter [I’ve done this on a friend’s 981, but it should be similar for the 987]. If it is the fan you’ll hear it better, as well as being able to make sure that it’s spinning freely.

Enjoy your Euro trip, and I hope that the Cayman behaves itself.

Jeff
Click to expand...
Different on 987. Glove box has to be removed to drop the fan down into the footwell.
 
Mine did exactly the same.
Then packed in.
Quick Google search told me I was likely low on gas.
After investigation, found both condensers were leaking.
Had them both replaced.
Sorted.
If it's any help, Groupon are doing a regas at ATS for £47.
They do a leak test first.
If they find your system is leaking, they refund you your £47.
Just had this done on my old Mondeo.
Hope this helps.
 
If the air-con is blowing ice cold, it's not a leak. Re-gassing equipment carries out a limited leak test before gassing. However this is not definitive.
When my AC stopped working, I suspected a condenser leak. A large chain (not ATS) were offering free AC checks. I was assured that the machine would not re-gas if the test failed. Test passed, AC re-gassed and was fine for a few days. They re-gassed again FOC, same result. I then took the car to a local garage which does AC repairs. They used a fluorescent dye in the fluid which allowed them to detect the leak, condenser as suspected. They were horrified that the chain did not add dye when re-gassing.
 
ianthow said:
If the air-con is blowing ice cold, it's not a leak. Re-gassing equipment carries out a limited leak test before gassing. However this is not definitive.
When my AC stopped working, I suspected a condenser leak. A large chain (not ATS) were offering free AC checks. I was assured that the machine would not re-gas if the test failed. Test passed, AC re-gassed and was fine for a few days. They re-gassed again FOC, same result. I then took the car to a local garage which does AC repairs. They used a fluorescent dye in the fluid which allowed them to detect the leak, condenser as suspected. They were horrified that the chain did not add dye when re-gassing.
Click to expand...
Sometimes it's difficult to know what to do for the best. When mine was serviced at a reputable indie, they told me the gas was low. Checked it for leaks. Said it was fine and topped it up with 500g of refrigerant. Holds 850g apparently. £90.
9 months later the hissing started. Month after that, the AC packed up.
The indie I use now found it straight away. Both condensers rotten.
Repaired. Still going strong a year later. 👍😊
 
Thanks all, that's very helpful, certainly gives me a few places to start looking. It will probably have to wait until after the holidays as I'm a bit reluctant to start pulling the car apart a week before we go. Hopefully the AC will see us through the holiday and I can investigate further when I'm not going to be so reliant on it as the weather cools. (y)
 
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