2004 screw Lariat 5.4

I've just had the truck a couple of days and so I can describe exactly when this noise occurs, but when driving at speed (say 40 to 60) sometimes I hear a short toooosshhh noise lasting about a half second. It sounds like some type of presure release noise. It happens 3 or 4 times in say a 10 to 20 minute period. Like I said, hasn't happened enough to correlate to any driving manueuver I'm making. It is hard to tell where it is coming from. It sounds like it is from underneath the cab, but could be the engine compartment.

Does anyone know what this noise could be?

Thanks,
Jess

 

I think the noise comes from the air conditioner compressor. Mine does it when the heat is on. I don't think it is anything to worry about.
Truck on!

 

Unless you have air brakes.... it is probably the A/C.
mk

 

Mine makes this sound all the time also...even when I am parked.

 

Yeah, I agree with the comment that it is the compressor. The compressor is used in both air condition and windshield defrost mode so you should notice the same type of noise in either mode. Try placing the setting to floor only with the air conditioner off. If you do not hear the noise, there's your answer.

 

Is this going to get moved to the "pressure release sound forum"

 

Just dont say anything annoying