2002 Liberty Heater only blows hot but ac is fully charged

[DavidV]

Hello everybody. I'm new here. I'm trying to see if anyone has any ideas about this odd problem we're having with my daughter's 2002 Liberty Limited. When you turn the heater controls to cold, the heat doesn't turn off and continually overpowers the air conditioning. You can feel the ac chill at the vent when the engine is cold, but as soon as it warms up, it's just hot air. I have verified that the ac system is not low on freon. I tried intalling a cutoff valve into the coolant line going into the heater core, but still it blows hot air. I had thought I had read somewhere that the problem is with the mixer box buried in the dash, and it's like $5k to fix because of all the labor involved. Looking again today, I can't find that information anymore, so I have no idea if it was actually addressing what is happening or if it was a google mismatch. Has anyone else run into this problem? The AI answer I received in my search today suggested that the mixer box would be more likely to cause there to be no heat rather than only heat. That it still gets hot when I prevent coolant from entering the core is baffling to me. I'm not totally new to working on cars, but this is the only Jeep I've ever worked on, and I don't usually work on stuff newer than the 90s. Any help would be greatly appreciated. She's getting baked alive in this summer heat!

 

[NewKJMudder]

Hello everybody. I'm new here. I'm trying to see if anyone has any ideas about this odd problem we're having with my daughter's 2002 Liberty Limited. When you turn the heater controls to cold, the heat doesn't turn off and continually overpowers the air conditioning. You can feel the ac chill at the vent when the engine is cold, but as soon as it warms up, it's just hot air. I have verified that the ac system is not low on freon. I tried intalling a cutoff valve into the coolant line going into the heater core, but still it blows hot air. I had thought I had read somewhere that the problem is with the mixer box buried in the dash, and it's like $5k to fix because of all the labor involved. Looking again today, I can't find that information anymore, so I have no idea if it was actually addressing what is happening or if it was a google mismatch. Has anyone else run into this problem? The AI answer I received in my search today suggested that the mixer box would be more likely to cause there to be no heat rather than only heat. That it still gets hot when I prevent coolant from entering the core is baffling to me. I'm not totally new to working on cars, but this is the only Jeep I've ever worked on, and I don't usually work on stuff newer than the 90s. Any help would be greatly appreciated. She's getting baked alive in this summer heat!

 

[NewKJMudder]

Mine is the opposite. The A/C blows ice cold but only in the full blast position. The Heater doesn't work at all. It just keeps blowing cool air.

 

[DadOSix]

Hello everybody. I'm new here. I'm trying to see if anyone has any ideas about this odd problem we're having with my daughter's 2002 Liberty Limited. When you turn the heater controls to cold, the heat doesn't turn off and continually overpowers the air conditioning. You can feel the ac chill at the vent when the engine is cold, but as soon as it warms up, it's just hot air. I have verified that the ac system is not low on freon. I tried intalling a cutoff valve into the coolant line going into the heater core, but still it blows hot air. I had thought I had read somewhere that the problem is with the mixer box buried in the dash, and it's like $5k to fix because of all the labor involved. Looking again today, I can't find that information anymore, so I have no idea if it was actually addressing what is happening or if it was a google mismatch. Has anyone else run into this problem? The AI answer I received in my search today suggested that the mixer box would be more likely to cause there to be no heat rather than only heat. That it still gets hot when I prevent coolant from entering the core is baffling to me. I'm not totally new to working on cars, but this is the only Jeep I've ever worked on, and I don't usually work on stuff newer than the 90s. Any help would be greatly appreciated. She's getting baked alive in this summer heat!

There is a lot to read here, but i wonder - you say you have cold air at startup at the vent and the freon is not low. Have you confirmed that the compressor is actually pulling in?

When the system pressures are correct, the switches allow the 12v to feed to the a/c compressor clutch. Easy to tell - with the a/c off, the middle of the compressor pulley - looking at it from front, will be stationary. If the clutch is engaged, the whole thing spins - center and the pulley. If your center is not spinning with a/c on, there is an issue with the clutch / compressor.

 

[mercdudecbr600]

The AC compressor has a loud click when engaged. Most likely, it's a bad clutch and the compressor is not engaged, but also check your hi and lo pressure switches. I had one go bad and Firestone exploded my compressor line. After that, I just replaced everything in the system - not expensive or hard to do. Probably cheaper to do that than to give it to a "tech" at a shop. YMMV.

 

[JeepLibertyKK]

Are the HVAC blend door actuators working properly? On the KK-series Liberty like mine, there are three. Two on the drivers’ side, one on the passenger side, all under the dash. Not sure how many on your KJ-series.

 

[Krf]

Hello everybody. I'm new here. I'm trying to see if anyone has any ideas about this odd problem we're having with my daughter's 2002 Liberty Limited. When you turn the heater controls to cold, the heat doesn't turn off and continually overpowers the air conditioning. You can feel the ac chill at the vent when the engine is cold, but as soon as it warms up, it's just hot air. I have verified that the ac system is not low on freon. I tried intalling a cutoff valve into the coolant line going into the heater core, but still it blows hot air. I had thought I had read somewhere that the problem is with the mixer box buried in the dash, and it's like $5k to fix because of all the labor involved. Looking again today, I can't find that information anymore, so I have no idea if it was actually addressing what is happening or if it was a google mismatch. Has anyone else run into this problem? The AI answer I received in my search today suggested that the mixer box would be more likely to cause there to be no heat rather than only heat. That it still gets hot when I prevent coolant from entering the core is baffling to me. I'm not totally new to working on cars, but this is the only Jeep I've ever worked on, and I don't usually work on stuff newer than the 90s. Any help would be greatly appreciated. She's getting baked alive in this summer heat!

Most likely a problem with a blend door. I had the same problem with my Dodge Durango, and it was caused by a blend door stuck in the hot position. It can be caused by either a bad actuator or a broken door shaft (my problem). If it's the door, you will have to take the affected blower assembly apart to replace it. Not an easy job.

 

[eldredg]

Hello everybody. I'm new here. I'm trying to see if anyone has any ideas about this odd problem we're having with my daughter's 2002 Liberty Limited. When you turn the heater controls to cold, the heat doesn't turn off and continually overpowers the air conditioning. You can feel the ac chill at the vent when the engine is cold, but as soon as it warms up, it's just hot air. I have verified that the ac system is not low on freon. I tried intalling a cutoff valve into the coolant line going into the heater core, but still it blows hot air. I had thought I had read somewhere that the problem is with the mixer box buried in the dash, and it's like $5k to fix because of all the labor involved. Looking again today, I can't find that information anymore, so I have no idea if it was actually addressing what is happening or if it was a google mismatch. Has anyone else run into this problem? The AI answer I received in my search today suggested that the mixer box would be more likely to cause there to be no heat rather than only heat. That it still gets hot when I prevent coolant from entering the core is baffling to me. I'm not totally new to working on cars, but this is the only Jeep I've ever worked on, and I don't usually work on stuff newer than the 90s. Any help would be greatly appreciated. She's getting baked alive in this summer heat!

Hello everybody. I'm new here. I'm trying to see if anyone has any ideas about this odd problem we're having with my daughter's 2002 Liberty Limited. When you turn the heater controls to cold, the heat doesn't turn off and continually overpowers the air conditioning. You can feel the ac chill at the vent when the engine is cold, but as soon as it warms up, it's just hot air. I have verified that the ac system is not low on freon. I tried intalling a cutoff valve into the coolant line going into the heater core, but still it blows hot air. I had thought I had read somewhere that the problem is with the mixer box buried in the dash, and it's like $5k to fix because of all the labor involved. Looking again today, I can't find that information anymore, so I have no idea if it was actually addressing what is happening or if it was a google mismatch. Has anyone else run into this problem? The AI answer I received in my search today suggested that the mixer box would be more likely to cause there to be no heat rather than only heat. That it still gets hot when I prevent coolant from entering the core is baffling to me. I'm not totally new to working on cars, but this is the only Jeep I've ever worked on, and I don't usually work on stuff newer than the 90s. Any help would be greatly appreciated. She's getting baked alive in this summer heat!

1) Blend door actuator is vacuum operated, so a vacuum line leak will make it inoperable. Stuck door or actuator failure is often cause of this. Check for vacuum leaks in old rubber hoses. 2) I've read that some folks have found the bump on the duct bottom under the actuator shaft, below / behind glove box(?), drilled a hole through it to the shaft bottom and used a screwdriver to move blend door when actuator failed. Apparently the door shaft has a slot in the bottom? 3) My 2003 KJ had a stuck actuator door with worst issue, jammed in duct so duct was replaced with duct from salvage yard. Didn't cost $5K, but wasn't cheap.

 

[mateorosi]

Had almost the same issue on my old Liberty. Ended up being the blend door actuator stuck halfway, so even when I turned it to cold, it still pushed hot air. Pulling the dash is bad, but some folks cut an access panel instead of paying thousands. I remember digging through random guides and even Sunpentown manuals just to cross-check airflow diagrams, lol. Might be worth checking the actuator first.