I only have air moving through the defrost vents....I've replaced the Vacuum line and the Blend Door actuator...where should i go from here?
HVAC only works on defrost
- Thread starter Shelly1367
- Start date
You most likely have a vacuum leak which has put the HVAC in safety mode (defrost only). Most leaks occur under the hood. There's a plastic vacuum line that runs under the hood from the intake manifold, along the big wire bundle on the firewall and through the firewall near the battery. That line also has a 'T' on it. Check that line and the 'T' really good.
OP
Yeah I've replaced that line...the 'T' seemed to be fine (but I'll inspect it again). Then I replaced the actuator door (under the dash on the passenger side) Now I'm just wondering where to look next? Maybe the actuator motor?
is your engine otherwise healthy? I don't know how bad it would have to be to get to that point, but it's theoretically possible for the engine to not be producing enough vacuum to drive the actuator.
Mine had a crack in the line and would work at idle but not on the highway when vacuum was lower.
Mine had a crack in the line and would work at idle but not on the highway when vacuum was lower.
It's time to do a smoke test. Believe me when I say that it's almost certainly a vacuum leak.
The exact same thing happened to mine recently and it was a vacuum leak. The issue is that often times these vacuum leaks are impossible to see with your naked eye, and you need a smoke machine in order to actually find out where they are.
The exact same thing happened to mine recently and it was a vacuum leak. The issue is that often times these vacuum leaks are impossible to see with your naked eye, and you need a smoke machine in order to actually find out where they are.
OP
Engines great...purrs like a kitten. and I don't notice any difference in the defrost speed when hubby accelerates
OP
I would get my hands on every vacuum fitting and hose from the intake manifold under the throttle body to each of the terminations, the hard plastic lines can harden and split/crack over time and the rubber fittings may look visually solid but will perish with heat and time. Had one of the rubber fittings on my son's TJ that looked solid crumble in my hand and that was in 2010 on an 01' Jeep.
Sitting at idle will the vents operate properly ?
Sitting at idle will the vents operate properly ?
Sorry to be dense...but how do you do a smoke test?
Here is one of many YouTube videos on the subject:
OP
Remove your glove box and inspect all the vacuum lines, especially the harness that plugs into the back of the control panel. Also inspect the vacuum lines near the upper right of the accelerator pedal. Also, you stated you checked the vacuum lines in the engine compartment. Take a look at this diagram and make sure you didn’t overlook an area, such as the reservoir under the battery tray. The vacuum line assembly under the hood is available for less than $20 shipped. Part number is 55037637AB
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OP
Mine had that issue and a little vent tube above the driver foot well (in the center section) can come loose. It’s quick and easy to check (under the blue/black wire is a brown hose or two connected to the black cylinder):
OP
i believe the door that the stem breaks off of , and keeps the defrost open is the one on the DRIVERS side under the dash ... the actuator for it should have blue and yellow tubes to it ... what year ???? If you remove the knee panel its easier to see in there ...
OP
it is a 2006
I put on a new door actuator on with no luck and the brown vac line (Like the photo above) under the driver side was attached and no visible cracks
I’ll remove the knee panel and check out the drivers side again
Check post #11 and locate the vac line from where it enters the cab and try and find #9 reservoir and trace the line to confirm it's still connected.
That's what mine did originally but now it only blows defrost. That makes me more confident that it's a vacuum leak.