2012 Jeep Liberty w/ Very Little HVAC Heat

JeepLibertyKK · Aug 24, 2024

Hello;

I have a 2012 Jeep Liberty Sport that has very little heat from the HVAC system. After a long warm-up period and then driving about three miles, I get temperatures of 58.5° on the drivers-side defroster and temperatures of 65.3° on the passenger-side defroster. That was barely above the ambient air temperatures. The Liberty used to high heat temperature readings within just a few minutes. It would blast you out in a short period of time. Photo shows Liberty at normal operating temperature.

I recently changed out the coolant and installed a new OEM thermostat.

What would be the next steps on diagnosing the issue? Winter is coming!
Thank-you!

lfhoward · Aug 24, 2024

Next I would check the blend door is operating right. In the drivers footwell, inboard side, you’ll see two actuator motors on the side of the air distribution box. (You might have to remove the cardboard kick cover first.) One actuator is the mode door that does the position (face, feet, defrost) and the other is the blend door that does heat and cold. I think the blend door actuator is the one closest to the drivers seat and the mode door is higher up under the dash. Either way, run your climate knobs through the positions and make sure you can hear/see the actuators moving. (FYI a third actuator lives behind the glove box on the passengers side and does the recirculate vs outside air function). If your blend door actuator doesn’t move, or if you hear clicking like broken plastic gears, those would be one option.

Another option is that your heater core is plugged the old fashioned way with sludge from the radiator. If your coolant in the overflow under the hood is green instead of reddish or orange, someone put the wrong coolant in at some point. Mixing the proper HOAT coolant with anything else can cause goo to form which clogs engine passages, radiators, and heater cores. If you see green coolant I would take it to the dealer to get a complete coolant flush. Or you can do it yourself but be sure to use HOAT when you fill it back up. Zerex G05 is a HOAT option that works and it is orange in color. Mopar’s is more reddish.

Regardless of coolant, you can also do a heater core flush, hoping to clear it out. That can work sometimes. If the goo is too much, a heater core replacement would be a last resort.

lfhoward · Aug 24, 2024

I needed to replace the air distribution box at one point for broken plastic gears on the mode door. This thread will give you an idea of where the actuators are and what they look like. Also a dash disassemble is in there in case the air distribution box or heater core needs to be replaced.

LOST JEEPS • View topic - HOW TO: Fix stuck HVAC mode door\actuator

JeepLibertyKK · Aug 25, 2024

lfhoward said:
Next I would check the blend door is operating right. In the drivers footwell, inboard side, you’ll see two actuator motors on the side of the air distribution box. (You might have to remove the cardboard kick cover first.) One actuator is the mode door that does the position (face, feet, defrost) and the other is the blend door that does heat and cold. I think the blend door actuator is the one closest to the drivers seat and the mode door is higher up under the dash. Either way, run your climate knobs through the positions and make sure you can hear/see the actuators moving. (FYI a third actuator lives behind the glove box on the passengers side and does the recirculate vs outside air function). If your blend door actuator doesn’t move, or if you hear clicking like broken plastic gears, those would be one option.

Another option is that your heater core is plugged the old fashioned way with sludge from the radiator. If your coolant in the overflow under the hood is green instead of reddish or orange, someone put the wrong coolant in at some point. Mixing the proper HOAT coolant with anything else can cause goo to form which clogs engine passages, radiators, and heater cores. If you see green coolant I would take it to the dealer to get a complete coolant flush. Or you can do it yourself but be sure to use HOAT when you fill it back up. Zerex G05 is a HOAT option that works and it is orange in color. Mopar’s is more reddish.

Regardless of coolant, you can also do a heater core flush, hoping to clear it out. That can work sometimes. If the goo is too much, a heater core replacement would be a last resort.

Thank you for both your extensive replies. It has had one previous coolant flush and has always had the proper HOAT.

Dirtyrat · Aug 26, 2024

JeepLibertyKK said:
Hello;

I have a 2012 Jeep Liberty Sport that has very little heat from the HVAC system. After a long warm-up period and then driving about three miles, I get temperatures of 58.5° on the drivers-side defroster and temperatures of 65.3° on the passenger-side defroster. That was barely above the ambient air temperatures. The Liberty used to high heat temperature readings within just a few minutes. It would blast you out in a short period of time. Photo shows Liberty at normal operating temperature.

I recently changed out the coolant and installed a new OEM thermostat.

What would be the next steps on diagnosing the issue? Winter is coming!
Thank-you!

Hello,
You can try burping your system. There is an Allen wrench plug on your thermostat housing. Loosen it. Not take it all the way out. That will release any air in the system. If that doesn’t work, didn’t work for me, try back flushing the heater core. More than likely plugged and needs replacing.

jeepman1946 · Sep 1, 2024

JeepLibertyKK said:
Hello;

I have a 2012 Jeep Liberty Sport that has very little heat from the HVAC system. After a long warm-up period and then driving about three miles, I get temperatures of 58.5° on the drivers-side defroster and temperatures of 65.3° on the passenger-side defroster. That was barely above the ambient air temperatures. The Liberty used to high heat temperature readings within just a few minutes. It would blast you out in a short period of time. Photo shows Liberty at normal operating temperature.

I recently changed out the coolant and installed a new OEM thermostat.

What would be the next steps on diagnosing the issue? Winter is coming!
Thank-you!

I had mine at the dealer for A/C not staying cold. The diagnostic test did NOT find the problem. Not sure how they pinned it down. They decided it needs the module with the control knobs. He warned me it would have issues with heat in winter. There is a door that controls the temperature and if it doesn't stay in place you have A/C blowing steadily warmer air and in winter the air will not stay hot. I hope yours is not the problem with the module, they gave me a price of $450 installed. But if it solves the problem go for it. A freezing car in winter is not fun.

2012 Jeep Liberty w/ Very Little HVAC Heat

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