David, A hissing AC mode switch needs to be repaired or replaced. The loud ticking sound could be your AC compressor clutch rapidly engaging and disengaging. "We're here to help you" DMC Help / De Lorean Services / <dmchelp@xxxx> Web Site: <www.deloreanservices.com> ----- Original Message ----- From: <Delorean17@xxxx> To: <dmcnews@xxxxxxxxxxx> Sent: Saturday, November 25, 2000 12:24 PM Subject: [DML] mode switch question > Hello, > When I purchased my car all of the vacuum lines were disconnected behind > the mode switch. I hooked them up like they are supposed to be and none of > the vent doors open except the floor vents. (I have the interior out of the > car now so I can see them all) I also here a constant hissing sound from the > switch. would this indicate a bad switch or is there something else I should > try first? all hose connections are good. > also, when I drive with the A/C pump on I get a loud tick from the engine > compartment at around 3500 RPMS but when i turn the AC off it goes away. > any ideas on that? > > Thank You > David