Heater / Block heater issues

[96Cherokee]

I have a 2013 Rubicon Unlimited, and I've been having major heater issues.  I've been getting cold air on the left side of the Jeep, and lukewarm air on the right.  After a bunch of research, I've heard of either flushing the coolant (which I had done at an oil change shop), or going all out and replacing the heater core.  Perhaps a better flush, a reverse flush, is in order.  Has anyone had any luck with this, or does it only work for a short time, and then you're back to the drawing board?

The other question is about the block heater: I've never used it until now and the Jeep starts fine without it, but every other vehicle I've owned the heater made a quiet hissing sound.  I can't hear anything with the Rubicon (yes I had power to it for sure), which makes me think it's not working.  Any insight on that?

Why is it that my new Jeep has all the problems and the '96 and '94 Cherokees are fine? 

[MattMan]

Just finished going through all this myself.

• Very likely heater core is partially plugged (mileage?)
• Back flushing is a temporary fix and likely won’t be much improvement for very long if you only have lukewarm air on the passenger side
• Unfortunately the only real solution is to replace the heater core (you have my sympathy)
• I’ve been told that the Block heater is under the intake manifold; but I’ve also seen technical drawings that show it located along upper rear passenger side of the block but either way, no it doesn’t hiss like a traditional block-style. Mine works great and I’ve never heard a thing.

Got nuthin’ for you on your last question... 

[96Cherokee]

Thanks, MattMan!
Yeah, I feel like if I pay for the back-flush it may temporarily help, but then I'll probably end up paying for the whole core later anyway.  Grumble.  I have about 90,000km or so.  Good to know about the block heater.  It's been hard to tell because the jeep starts just fine with or without it, which is a good thing.

Thanks for the info!  Anyone else wanna chime in?

[Immortal]

Grab a digital multimeter ($20 PA one will work fine), ohm out the plug-in on the block heater. OL means no bueno. Any sort of resistance means it's still good.

[96Cherokee]

Heater issue solved by the good folks at Broken Axle.  Thanks guys!  New heater core installed.

[MattMan]

Heater issue solved by the good folks at Broken Axle.  Thanks guys!  New heater core installed.

Good to hear!
Just in time for the warm weather.