My car is making a high pitch noise from the glove box area, usually when you first start it on a hot day. It doesn’t change if you put the heater fan on ,but it does get louder if you step on the gas .Also you can’t hear it from under the hood ,only in the cab .Any ideas what it could be ? Thanks!
The vent system utilizes both electric and vacuum motors for various functions of the vent system. If one of these vacuum motor diaphrams developes a leak, it can cause a high pitched sound of vacuum passing thru the leak.
A quick check for this is, locate the vacuum supply hose for the vent system under the hood. Pinch off this hose with a pair of pliers. Now start the engine. If the noise is gone, one of the vacuum motors for the vent system has a diaphram leak.
how can you tell which vacuum line is the one?