A/C issues

    2012 Grand Cherokee


    AC hasnt been up to snuff over past month or so.


    1) If sitting in driveway or parking lot on hot day, will take very long to cool down- just blows barely cool air until I get on the road and moving


    2) Several times recently during the heat wave (over 90 degrees) when I was on the turnpike, it would just go out. The blower dial would be on max setting, but would be barely blowing out as if were on the minimum setting. Then when I got of turn pike and onto lower speed roads, would kick back in again. Or in some cases, it would kick back in the next time I started it up.


    3) Cruising around on local streets it seems to work fine- blows well, and air is cold


    Its just out of warranty, so trying to gauge how big the problem is going to be and cost.


    Sound like needs freon recharge? Temp sensor? Or was it just being overworked on the 95 degree days combined with turnpike speeds?

    I would start with the simple fix and try recharging the system. Could be a compressor, evaporator or what its called where the liquid expands to create the cold air.



    Larger system but a similar issue was at my friends house. AC was always running to keep house cool. Burned up something in it (minor) and still running all the time. Next time it went out they checked the system and it was low. Recharged his house system or whatever and it runs so much less keeping his house cool.



    Thats where I would start.

    Is the cooling fan running when the a/c is on? We had damn near the exact same behavior in the WJ and it was due to the electric fan...wasn't kicking on with the a/c, only to cool the motor.


    --Ian

    I guess, I mean its blowing air, just not cold (when parked or driving slow in rush hour).


    High speeds its the opposite problem. Blows cold air, but you have to put hand up to vent to feel it. Thats probably a fan problem.


    The highway problem was random, not every day. It happened specifically on days when it was over 90 degrees combined with me driving over 75mph.


    This weekend was cooler out and I was driving 65 mph, and it worked fine.


    Is it possible that the high speeds/hot day is causing the engine to get very hot and hijacking the fan? I dont know if thats even possible, but fan problem seems to correlate with extra hot engine days


    I'm referring to the fan under the hood....not the hvac fan. For the a/c to function the condenser needs to be cooled. At a stop or low speed if the engine cooling fan is not engaged it will heat soak and cause the output in the cabin to be warm. Once you reach a certain speed the lack of a fan is negated and it'll blow cool. The freeway issue is interesting, though, my only explanation for that would be aerodynamics maybe? Over a certain speed and airflow through the condenser/rad could actually decrease? Either way when the a/c is engaged the underhood cooling fan should be on all the time instead of only turning on when the engine temps dictate....check that first.


    --Ian

    To add a little to what Ian is saying... You will hear the click of the compressor and then a very easily heard fan noise immediately following the compressor start up.



    If you can hear the compressor engaging and the fan as Ian mentioned I would top off the charge. Make sure to not use the "fix a leak" kind as that makes it a lot more expensive if/when you have to have it professionally repaired.

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