Heater Core Question Updated

[2010VibeIN]

I am having some heat problem in my 2010 Vibe 2.4L engine. I get heat out of the vent on the drivers side front vent but cold in the other vents.Every once in awhile I will get heat out of all 4 vents. The heat is good out of the 1 vent when I use the heat. I also hear a sloshing noise coming from the dash where the heater core is located.I had the heater core flushed and had perfect heat for about 3 days but it went back to where it was before I done it.
The mechanic who done the work said the heater core needs replaced but a different mechanic says that the Blend door is probably bad.
I can't do the work myself so I have to pay a mechanic to do the work.If it is the heater core I plan to have them flush the entire system,but will that be enough to keep the new heater core from stopping up. Also I don't have any antifreeze on the floorboards,the windows don't fog up and I don't loose any antifreeze. It's confusing me on what to do as far as fixing it and can't afford to fix the wrong thing. Also the car doesn't overheat.The temp gauge stays in the normal place.
Any ideas?

[sideshowalan]

Since flushing the system fixed it for a few days, the problem is likely not the blend door.
Have they tried bleeding the coolant or a drain/flush/fill cycle? Air in the system would cause that kind problem.

[vibrologist]

I agree with sideshowalan.

There is air in the heater core. I would ask the shop to bleed the system again. It is not unusual for it to take a few bleeds to get all the air out.

[2010VibeIN]

Ok Thanks for replying I will talk to them Monday when it goes in.

[vibrologist]

forgot to mention this: your Vibe looks great!!

[ctgottapee]

As long as the initial fix was just in your head, that would be a good start

Make sure the heater core has no trapped air.
My guess would be if the heater core did have trapped air, you would get lukewarm air out of all the vents as they all lead from the same source

Does anyone know, can you see the blend door in action if you remove the glove compartment and air filter and peek in there??

[2010VibeIN]

Strangest thing tonight while working. I had heat as I would normally have it out of all the vents. It was as hot as it should be. This car has really caused me a lot of confusion on what the problem could be. I never lost heat at all and it got to 35 degrees which the night before I had no heat except for 1 vent. I still heard the antifreeze swishing around in the dash though.

[2010VibeIN]

Heater core was plugged up but wasn't changed. They said that it will just plug back up again and to bring it back when it plugs up again and they will continue doing that until it no longer works and we will go from there.They didn't want to change it and take my money when they know it will only plug up again. They charged me $50 to do it and said they will do it and not charge me every time they do it since they know what to do and it won't take long.
Hopefully it won't take long to flush it all out.I plan to go every 2 weeks to have them flush it to hurry and get it out. I don't have much of a choice but to do it this way and can't afford another car. My car has 153,000 miles on it and it makes me very upset because I bought the car hoping it would last me for a few years and I have had it less then a year. Last year I didn't have a problem with the heat so it can't be extremely bad.I'll just have to keep an eye on the color of the coolant as well.