A few years ago I had the same problem and I search this forum. I checked the vacuum lines between the battery and the firewall and found one broken. I fixed it with a piece of vacuum line and all worked well. It was the bottom of the t-fitting and went towards the back of the engine & firewall along the passenger side of the valve cover.
Last weekend I replaced my timing chains, guides, tensioners, cam phasers, solenoids, lower timing chain sprocket, and upgraded the oil pump. I had to disconnect the A/C lines that run over the passenger valve cover so I replaced all of the o-rings in the A/C lines under the hood area. After starting the car everything ran smoothly. I turned on the fan to have some airflow in the car and the air defaulted out of the defrost vents again, regardless of which setting I picked.
Looking under the hood I discovered that the vacuum line between the battery and the firewall had broken again during all of the work removing the powertrain module for my timing component replacements. I removed the broken vacuum line from the bottom of the t-fitting to where it enters a convoluted plastic covering along with another vacuum line and replaced it with rubber vacuum line. I thought my problem would be fixed.
I fixed the vacuum leaking sound but the vents are still only blowing out of the defrost. I've inspected all the lines and they all seem to be good. The only questionable fitting is where the hard plastic line leaves the t-fitting and goes behind the battery box and connects to the vacuum reservoir. The rubber connection at that point seems a little soft, so I will pick up some vacuum line this week and replace it from the t-fitting to the vacuum reservoir behind the battery box. If that isn't it, I'm not sure where to go. The vacuum line that comes out of the bottom of the t-fitting is the one that has broken twice. It runs along the passenger valve cover and disappears behind the engine and firewall so tracing it all the way back wouldn't be easy.
Does anyone have any suggestions?
Last weekend I replaced my timing chains, guides, tensioners, cam phasers, solenoids, lower timing chain sprocket, and upgraded the oil pump. I had to disconnect the A/C lines that run over the passenger valve cover so I replaced all of the o-rings in the A/C lines under the hood area. After starting the car everything ran smoothly. I turned on the fan to have some airflow in the car and the air defaulted out of the defrost vents again, regardless of which setting I picked.
Looking under the hood I discovered that the vacuum line between the battery and the firewall had broken again during all of the work removing the powertrain module for my timing component replacements. I removed the broken vacuum line from the bottom of the t-fitting to where it enters a convoluted plastic covering along with another vacuum line and replaced it with rubber vacuum line. I thought my problem would be fixed.
I fixed the vacuum leaking sound but the vents are still only blowing out of the defrost. I've inspected all the lines and they all seem to be good. The only questionable fitting is where the hard plastic line leaves the t-fitting and goes behind the battery box and connects to the vacuum reservoir. The rubber connection at that point seems a little soft, so I will pick up some vacuum line this week and replace it from the t-fitting to the vacuum reservoir behind the battery box. If that isn't it, I'm not sure where to go. The vacuum line that comes out of the bottom of the t-fitting is the one that has broken twice. It runs along the passenger valve cover and disappears behind the engine and firewall so tracing it all the way back wouldn't be easy.
Does anyone have any suggestions?
