A/C whistle

[azscotty77]

Hi
When I shut off my 2003 Astro 4.3 v-6 after running A/C, I get a high pitched whistle.What could cause this?
Also rear a/c blows, but blows warm.Does rear have it's own blower motor,drier etc.? Last time a/c was worked on was about 2 years ago for recharge/ leak fixed.Still blows ice cold.High speed on fan inoperative also-possibly relay or resistor?Thanks in advance for any help offered.

[HeresPaco]

Scotty, Sometimes you will hear a quiet slight hissing sound when first turning off the a/c as the system equalizes itself, your refridgerator does that too. But your whistle may be just a vacuum leak in a vacuum hose, connection or in one of the vacuum actuators for the a/c and heating under the dash. That may even have something to do with why you are not getting the rear a/c to work. The rear a/c does have it's own evaporator, control valves and electrical switches but I'm not sure it has a system refridgerant dryer like the main dryer under your hood. A dealer tech probably has seen these two problems many times and may be able to tell you exactly where to look for the culprit. I've heard that both of these complaints are a rather frequent problem to happen with the '95-'05 Astro & Safari.