AC vents acting up on extended trips...how serious?

MicroBruin · **Posted:** Fri May 09, 2014 3:22 pm

Well, after about an hour or two of driving in 80-90 degree temps, using recirculation, my vents seem to close up. I start hearing a whooshing sound behind the dash, but the air isn't coming out. If I fiddle with the vent selector, it sometimes helps. If I let the AC rest for a few minutes, it helps. I've read about issues on the Liberty with the vacuum operated blend door actuator...sometimes resulting in removal of the entire dash and lots of HVAC stuff. I really hope it's not that serious. I know the labor cost of fixing can get ridiculous, so I would probably have to tackle it myself. Anyone have any experience with this? I guess my first step will be to take a look behind the glove box, and see if there's access to the vacuum lines and connection/actuator. I'll check for dirt, dust, etc. Hopefully, this won't be a nightmare! It just seems odd that this only occurs after an hour or two of driving with AC. Thanks in advance to anyone who has ideas....

dkenny · **Posted:** Fri May 09, 2014 8:38 pm

rough guess..the A/C is slightly low on freon..
next you have this problem turn off the ac for a little while and see if the air flow improves and comes out cold
normally it turn tha ac off the air out of the vent with warm up quickly..unless the evaporator is frozen..

-dkenny

MicroBruin · **Posted:** Sat May 10, 2014 9:25 pm

Seems odd that low refrigerant affects the blend air actuator, but I've seen a couple other things mentioned online about it, too. Maybe it's causing it to freeze up after a while and then the sensor detects something wierd and starts playing with the blend door...I dunno. Will go get the temp and pressure checked and see if it needs to be topped off or recharged. Thanks.

flash7210 · **Posted:** Sat May 10, 2014 11:11 pm

Ive experienced this a few times before.
It's the AC evaporator freezing up. Kinda hard for air to flow through a block of ice.
When it happens I turn the AC off and switch it to outside air.
Once the ice melts normal air flow resumes.

DOC4444 · **Posted:** Sun May 11, 2014 9:57 am

Perhaps your AC drain is plugged. If the evaporator is freezing up, there is moisture there that should not be. If you are running the AC full blast in really hot weather, you will see a puddle quickly form under the Jeep if you park and leave it running for a couple minutes. If there is no puddle, the drain is plugged. You can usually clear it temporarily by just blowing compressed air in the outlet from the bottom. Depending on what plugged it, that easy fix may last months or barely a few days.

DOC

MicroBruin · **Posted:** Mon May 12, 2014 1:18 pm

DOC4444 wrote:

Perhaps your AC drain is plugged. If the evaporator is freezing up, there is moisture there that should not be. If you are running the AC full blast in really hot weather, you will see a puddle quickly form under the Jeep if you park and leave it running for a couple minutes. If there is no puddle, the drain is plugged. You can usually clear it temporarily by just blowing compressed air in the outlet from the bottom. Depending on what plugged it, that easy fix may last months or barely a few days.

DOC

Thanks, Doc....drain is good, though. There's always a good sized puddle under the truck after I park. I'm going to get the system checked, but I don't think it's a completely faulty actuator or blend door. The AC works too good for that....I'm betting on the refrigerant being low....we'll see....

MicroBruin · **Posted:** Sun May 18, 2014 11:32 pm

Ok...looks like the system was freezing up once in a while after a couple hours driving. I took it to my trusted AC place while in Miami, and it took about 2 minutes for them to tell me the pressure switch was bad. Freon level was fine...no leaks, just a bad pressure switch. Hopefully, that will be the end of the problem (fingers crossed).

AC vents acting up on extended trips...how serious?

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