Noise from cooling system

[Black69]

When using the air or just the fan to put some cool air into the truck, (2004 Suburban) I have a noise coming from under the dash and the cooling system. It is mostly heard at idle but is present most of the time. (have you ever tried to spell a noise sound) It is like a puurrt, puurrt, puurrt. If anyone has any ideas, it is driving my wife nuts. Thanks in advance.

[gmtech4]

get a video or audio clip posted or we cant help,,except guess

 

my crystal ball has been over worked and broke dam it !! lol

[Black69]

Here is a very poor video of the noise. With the volume up you can hear it. At this time the noise was not very loud but at times does increase, mostly when idling or slowing.

http://s18.photobucket.com/albums/b132/Black69/?action=view&current=Noise.mp4

 

Thanks for any help. Also this noise is not constant or predictable, just when it feels like it I guess.

Thanks for your help.

[txab]

Are you talking about the "humping on a squeaky bed sound"?

[Black69]

Yup that would be it. My daughter was making some of the other noises. Some times the noise sounds like purt, purt, purt.

[gmtech4]

is the fan on low?

[Black69]

Usually on 1 or 2. If it goes faster you don't notice the noise as the fan speed is louder. Also more prevalent when you are stopped as to moving.

[gmtech4]

does the noise go away on higher speeds ?

 

is it there when fan is off?

[Black69]

The sound is not there when the fan is off and also when the key is off. If you turn the key to on, after running the vehicle for a while, with the engine off, the sound returns.

[Wolfmanjohn]

Momentary/sudden change in refrigerant flow through the evaporator, perhaps? At lower fan speeds, that could be a normal thing.

[gmtech4]

what i m asking is ,

 

is the noise related to fan speed changes ?,if yes ,its the fan motor going for a crap

[Black69]

The speed of the fan does not make a difference. It's just easier to hear with the fan speed on 1 0r 2. Any higher than that you hear the air rushing and not the noise, even though the noise is still there. It's not consistant enough to pin down. I don't notice it when using the heater, only the ac or cold air, so it must be related to the cooling and not the heating side.

[gmtech4]

idk,use a stethascope and put against heater box is all i got ,good luck

[Black69]

The noise seems to be coming from the heater box area. If the fan is on 0, the noise is still there, if I turn the levers up for the heat the sound goes away and if I push the levers down for cool air the sound returns.

[GMCustomerService]

Has your concern been resolved? Please feel free to contact me as weill with the last eight of your VIN for more assistance. Thank you in advance.

 

Tricia, GM Customer Service.