AC Hissing

[michael.williams1]

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(?).

 

[911hillclimber]

Have to say my 987.2 2.9 2009/ 85K mile Boxster does not to this, but we do not use the A/C much tbh.

 

[Motorhead]

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

 

[michael.williams1]

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

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!

 

[ianthow]

Could the noise actually be from the fan, either something rubbing or the fan bearing?

 

[Motorhead]

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

 

[ianthow]

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

Different on 987. Glove box has to be removed to drop the fan down into the footwell.

 

[Steo68]

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.

 

[ianthow]

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.