Wierd sound inside dash. Hissing/Slurping. Anyone experience this?

[Tango71]

So I notice this occasionally, with the engine running I'll be at the drive through or just idling at a light and will hear this sound. I don't know if its A/C components or inside my heater core. Nothing is leaking and it makes no difference if I have the A/C on or off, the noise comes and goes as it pleases and it will do it momentarily then go away. RPM does usually go up a bit when this happens. Should I be concerned?

 

[papapoopski]

Hissing & Slurping? There's most likely a hooker in your glove box. Lure it out with dollar bills. Once it hits the street it will be in its natural habitat and will instinctually calm down and start showing some skin. Keep feeding it dollar bills and see what happens.

Sorry bud, couldn't resist. I only have dumb sarcastic comments for you. At least I'm keeping it at the top of the forum page.

Good luck with it.

 

[3rd gen king]

So I notice this occasionally, with the engine running I'll be at the drive through or just idling at a light and will hear this sound. I don't know if its A/C components or inside my heater core. Nothing is leaking and it makes no difference if I have the A/C on or off, the noise comes and goes as it pleases and it will do it momentarily then go away. RPM does usually go up a bit when this happens. Should I be concerned?

Truck runs good?

Then: pump up the volume and don't worry

 

[Tango71]

Truck runs good?

Then: pump up the volume and don't worry

Yeah the truck runs great which is why I don't get what it is. Aside from hookers hiding in my glove box (I swear I thought I only had a flashlight and Service manual in there) I don't know what it could be.
Like I said I come to a stop, idle is fine then idle jumps up a bit, hissing sound is heard, after several moments it goes away and idle returns to normal.

 

[Sawgunner]

Is the windshield defrost on, because that will run the ac I think?

 

[3rd gen king]

Yeah the truck runs great which is why I don't get what it is. Aside from hookers hiding in my glove box (I swear I thought I only had a flashlight and Service manual in there) I don't know what it could be.
Like I said I come to a stop, idle is fine then idle jumps up a bit, hissing sound is heard, after several moments it goes away and idle returns to normal.

Try popping the hood and locating it

 

[Drcoffee]

When it happens turn everything off other than the engine and rule out the stereo & HVAC. If its still there, with the HVAC off, twist the heater temp control from cold to hot or visa versa. If no change, move the shifter to neutral and reverse.

A change in sound with engine speed makes me think it may be electrical coming through as radio interference.

 

[freshley]

me too

I've had this noise too. Make sure your heater (front and back) controls are set to cold and see if it goes away. From what I've been told, this is common and is just fluid running through the lines into the heater core. I never noticed this when mine was new but for some reason in the past year or so I have noticed it. Doesn't seem to hurt anything, so I've left it alone.

 

[Socco]

So I notice this occasionally, with the engine running I'll be at the drive through or just idling at a light and will hear this sound. I don't know if its A/C components or inside my heater core. Nothing is leaking and it makes no difference if I have the A/C on or off, the noise comes and goes as it pleases and it will do it momentarily then go away. RPM does usually go up a bit when this happens. Should I be concerned?

Nope. This sounds normal to me. Every few minutes the A/C compressor mag clutch energizes, engaging the drive belt. This causes the RPM to drop slightly.

Refrigerant starts to flow through the evaporator coil behind the glove box. Since you probably have the blower turned off or on low, you will hear like slight hissing/bubbling sound of the gas, this noise is always there when the compressor starts up.

The clutch is then released and the RPMs pick up again. IIRC the compressor is "exercised" to keep the shaft seal lubricated to prevent refrigerant loss.

 

[Blanco]

Nope. This sounds normal to me. Every few minutes the A/C compressor mag clutch energizes, engaging the drive belt. This causes the RPM to drop slightly.

Refrigerant starts to flow through the evaporator coil behind the glove box. Since you probably have the blower turned off or on low, you will hear like slight hissing/bubbling sound of the gas, this noise is always there when the compressor starts up.

The clutch is then released and the RPMs pick up again. IIRC the compressor is "exercised" to keep the shaft seal lubricated to prevent refrigerant loss.

Thanks. I've also been wondering what that sound is since I bought my Runner over a year ago. It's like a weird 'suction' sound emanating from behind the HVAC controls. I actually thought it was a leaf or something caught in there : )

 

[Tango71]

When it happens turn everything off other than the engine and rule out the stereo & HVAC. If its still there, with the HVAC off, twist the heater temp control from cold to hot or visa versa. If no change, move the shifter to neutral and reverse.

A change in sound with engine speed makes me think it may be electrical coming through as radio interference.

Cant be. Radio was off. Heat/blower and such were all off. Only thing running was the engine. Windows were up and it was in a quiet area anyway.

EDIT: Thanks. That makes a lot of sense now guys. And since a couple of you are experiencing this then I'm not so worried now.