A/C problem - JeepForum.com
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post #1 of 4 Old 09-29-2013, 10:45 PM Thread Starter
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1997 TJ Wrangler 
Join Date: Aug 2013
Location: Miami
Posts: 50
A/C problem

So I have noticed when I turn on my AC after having it off for a day or two because of me riding with no top, the AC makes a whistling noise and it doesn't blow from the normal vents, it blows from the defrost vents (when put on normal AC/snowflake symbol). So I would switch the power of the AC to full or switch over to the defrost and then back to normal AC, and then the whistle would go away and it will blow normally. But now, it is stuck in blowing on defrost, no matter which setting I put it to, (i.e I have it on normal AC and it is blowing from the defrost vents not normal vents) but it can hear each function turning on when I switch it, it just keeps blowing out of the defrost vents, not normal vents. This is very annoying and doesn't keep the jeep cool at all. Please help, thanks

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post #2 of 4 Old 09-29-2013, 11:08 PM
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2000 TJ Wrangler 
Join Date: Aug 2005
Location: Colorado
Posts: 21,538
Your HVAC system has a vacuum leak between the intake manifold and the HVAC panel mode select switch, or the switch its self is damaged...
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post #3 of 4 Old 09-29-2013, 11:41 PM
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2008 JK Wrangler 
Join Date: Aug 2013
Location: near Montreal
Posts: 881
Yup.knucklehead is on the right track.. that's a vacuum leak.... in my 20+ years of repairs never seen a bad hvac head (vacuum related) problem but hey? everything is possible! check under your battery... there is a vacuum reserve canister... and check all vacuum lines. they go from manifold ...across firewall...enter firewall in between heater hoses. most problems are near reserve in canister under battery from battery acid leak_ (some split to go to cruise to the drivers side). some split at intake to firewall (TORQUE TWIST).unrepaired eventually you may get dtc and a p0171 set. if you hear a whizzing sound inside you may have a partially unplugged hvac vacuum plug or line (look under glovebox and follow sound) .
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post #4 of 4 Old 09-30-2013, 03:39 PM Thread Starter
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1997 TJ Wrangler 
Join Date: Aug 2013
Location: Miami
Posts: 50
Thanks guys, my vacuum line was just disconnected...I was looking too deep to notice something right in front of me lol
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