Hvac
#1
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This past week I have been having issues with the hvac controls, when ever I accelerate or speed up the heat will blow out the 4 vents on the dash. If I change the control to a different location it will change it, I looked in the engine bay and did not see any loose vacuum lines. It is a non- automatic hvac 4x4 98 blazer. Any suggestions would be greatly appreciated.
#2
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Your symptom indicates a vacuum leak. If the vacuum lines are OK as you mentioned, the vacuum check valve is not holding vacuum when you accelerate. This link shows where it is: http://i561.photobucket.com/albums/s...acuumlines.jpg Most auto parts stores stock them, cost is ~ $5. If that doesn't repair the problem, there is a vacuum leak
The link shows where all the vacuum lines go.
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#3
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Thanks, I did a lot of searching, but everything seemed to be opposite of what my problem was, I appreciate it.
#4
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Find the vacuum line under the hood that goes through the firewall; this is for the HVAC control. Remove the hose from the T and cap-off the T. Then go for a drive and see if the problem is gone.
Also the vacuum lines rot-out, especially the ones in the upper left area of the engine bay. Suggest just buying 10 feet of vacuum lines and replacing them all. Also check the check-valve for a leak.
Also the vacuum lines rot-out, especially the ones in the upper left area of the engine bay. Suggest just buying 10 feet of vacuum lines and replacing them all. Also check the check-valve for a leak.
#5
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I tried to pull the vac line from there and was not successful. I did not want to break the line, how easy is it to hookup the vacuum line that goes through fire wall back up? I might just replace it if it isn't too hard to do.
#6
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The HVAC line, (hard black plastic) goes from the back of the mode switch, through the firewall, and connects to a rubber line next to the ABS unit.
![](http://i561.photobucket.com/albums/ss58/cwhook/Vacuumlines.jpg)
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