Hello! Been lurking here for a while now and posting for the first time. When I was in college I had a 99 and loved it. Last week I went and found one just like it and bought a second 99! It's been great and has its minor issues but all stuff I've been working through. One strange issue I'm having is with the HVAC. Its an auto system with AC. I'm pretty sure I need to replace the blend door actuator because its either all heat or all cold, nothing regulated in between. Beyond that though, the directional flow (from defrost to dash to floor) works sporadically. Example: I'll turn the heat on and it starts at the dash vents. I move the air flow to the floor and maybe three minutes later the system finally decides to move to the floor. Then I'll switch it to defrost and maybe 2 minutes later it bumps up to defrost. Ocasionally I can hear a vacuum his under the dash as if there's a leak. I looked under and saw a piece with red and blue vacuum lines coming out of . Thats where the hiss is coming from. I pulled the two lines off and re seated them but it didnt help. What is that device? There's a rod that comes out of the top of it so I'm assuming it's what moves the air flow around. I looked briefly at the lines under the hood. From the distributor area I have a line that goes to what I think is the 4x4 actuator and another line comes out of that to a check valve then to a vacuum T. My real question is, why would it work sporadically? What should I look for? Thanks!

 

Anyone?

 

Ok I got the temperature adjusting correctly last night. All I have left to figure out is why my air flow adjusts when it wants to. Driving to work this morning I put it on floor. It moved to the floor eventually and about 5 minutes later I started hearing the hissing from under the drivers side dash. I moved the **** to defrost and the hissing stopped right away. I moved it back to floor and it returned again. About 10 minutes after that the selector was on floor and the flow decided to change to dash vents by itself! Any ideas? Where is the hissing coming from?

 

Leaking vac line