mario32

2001 Cherokee with the 4.0l, heater blows but just doesn't get hot, I had the system check (pressure check and no leaks) first thought it might be the core but now I don't know, new antifreeze, because I had to replace the radiator and water pump when I bought it so I'm really not sure if it worked before or not temp gage shows correct temp constantly at 195/200 degrees, so any ideas would be helpful,

EZEARL

Could be this (per CCKen):

For those of you with a 1999 thru 2001 XJ, here's a diagram of the Blend-Air Door circuit. Up to and including 1998 XJ the Blend-Air Door was cable actuated.

Connector C209 can be accessed by rolling the glove box down.

Ground G107 is to the right of the glove box on the dashboard structure.

The Blend-Air Door motor is an electronic bridge circuit. I have no method of checking it.

The integrity of the ground circuit to G107 can be checked with an Ohmmeter from C209 pin 1, Blend-Air Door motor connector pin 7, and/or A/C Heater Control connector C2, pin 2.

If fuse F25 in the JB was blown, the HVAC blower would not work. Power to the Blend-Air Door motor, A/C Heater Control, and/or connector C209, can be checked using a Voltmeter at the connector pins shown, with the ignition switch in the RUN position.

djb383

Do both heater hoses get really hot? If everything under the dash works (the blend door etc.), the heater core could be plugged/crudded up.

mario32

if its the blender then the ac shouldn't work either right, cause I just had that charged and haven't used it yet, ill check on that tomorrow. how would you flush out the heater core, It did sit for months and that old antifreeze was pretty nasty

Wojtas

Back flush the heater core. Determine which is your intake hose and outtake hose. Intake will usually be hotter if your heat does not work and outtake will most likely be cold. go pick up some CLR from walmart, pour it into your outtake and into your heater core. use an air compressor in the outtake to get all the nasty gunk out and bam, heat works again (hopefully)

If i was not clear enough, here is a video of a backflush on a grand cherry with the same HVAC setup as any old cherry.

djb383

CLR specifically states on their web site "do not use in an automotive cooling system" . Must be a valid reason for them to say that.

mario32

back flushing seem to do the trick, thanks for all the tips.