I have a 2008 Jeep Liberty that I took into my local dealer in Dec. 2013 because it was blowing cool air on the driver
side and hot air on the passenger side. They said they replaced the heater core, which cost $1400 and all seemed fine until this year.
Now we have the same problem again. They flushed the system and said it was fixed. Two weeks later the problem has
returned. They now say the heater core is bad again and needs to be replaced and it is not covered under any warranty.
If I have it replaced at an independent repair shop would they be able to tell if the heater core was replaced two
years ago? I find it hard to believe that it would be the same problem as before and I am wondering if they really did
replace it back then.

We had the evaporator replaced in our 2008 Liberty in 2015, it was leaking freon. They replaced the heater core as well while they were in there b/c they didn't want to go back anytime soon. Real PIA job, I stopped by during the repair and they had everything from the front seats forward to the firewall/cowl out.

While the evaporator looked dirty with dust, lint and maybe some plant material on it the heater core that they took out looked clean and could very nearly pass for new. There were just a few small blemishes on the aluminum surface. Now I'm in TX and the heater didn't get used all that much.

If you are getting hot air on one side and not the other it sounds more like an air distribution problem instead of a core issue. JMO. Good luck, oh, and your cost to repair was comparable to mine.

hot air, even if it's only one one side, indicates the core is ok. look at a blend door being broken or a blend door motor not working. very good possibility that was the original issue if you had heat in one position and not others.

This is correct. Libertys are known for blend door issues. I believe specifically its that the door hinges on plastic pegs that just don't last but I am not positive on that.

Google the kj jeep forum and they discuss it at length.

Pretty sure its not the blend door. Like I said back in 2013 I had the same problem and the dealer claims they replaced the heater core which seemed to fix the problem until this year. Now the same problem. I took it in two weeks ago and they said they flushed the heater core which again appeared to of fixed the problem but this time only for a week or so. Now they claim the heater core needs to be replaced again for another $1400! My question is do you think an independent shop would be able to tell if the original core was ever replaced? I found a shop that will replace it for $650 but I want to know if the one he takes out is the original core or a replacement. If he says its original then the stealership is going to owe me $1400 from two years ago!

It will pretty difficult to tell you if the heater core was replaced after being in there for 2 years.
I would find a shop and have the heater core flushed before spending all that money. I have done hundreds of heater core flushing with success, I use a garden hose and some air pressure, go back n forth through the tubes.(also add small piece of heater hoses into an empty bottle, so I can see what is coming out). always clear up, (just limit the air pressure so you don't blow the heater core apart).
The heater core can be partially plugged, that is why you have heat on 1 side but not the other, just because you had this problem before,doesn't mean that it is the same problem. blend air doors and actuators do go bad. listen carefully, when you switch from cold to heat, you will hear an airflow change.if not the door isn't moving.
FLUSH it first, before spending the money.
Go to an independent shop and have it done.dealer is not the best place to go for a flush.

If you are plugging up heater cores this fast, you must have some nasty coolant, you have way more problems coming.

once a cooling system gets in a condition where contaminates build up, such as this case, it'a nearly impossible to recover. I have several customers that about every other year we're flushing their heater cores to regain full heat. I've did my 01 pickup a few years back and it's had impeccable service. Heater core is just a convenient place for "gunk" to accumulate. Just beware that flushing using high psi or "bursts" of air can damage a heater core and you might be pulling the dash again.