heat/air system going into defrost mode

[terryjh6]

just yesterday my a/c is working good and then my a/c duct system goes into defalt defrost mode, i know that that system is vacuum operated. is there a good place to start to look for a leak? thanks for the help,,Terry

 

[terryjh6]

help????

 

[garyk1970]

look for two hard vacumm lines coming out of pass fender by blower,one is heater control,the other is supply vaccum to switch control over radio.also possible control switch mentioned above went south.start car and see if you can hear vaccum hiss at switch,if so its leaking.

 

[jamier]

something to check

had a similar problem one day the ac fine the next no cold air , turned out to be the slider under the dash that opens the air bypass for the ac, I was able to access mine through the glove box. it should be just to the left you'll see the slider cable attached to it. Mine was cracked off from years of use, something worth checking...