I have very low heat from my 2001 Grand Cherokee.

vacuum leak. prolly same vacuum that goes.to.cruise control

I've got the same problem with my 02, I have checked all of the mode and blend doors and they all work, what has helped is turning on the recirc door after the engine is fully warmed up, if it starts to fog up inside I switch it to defrost, the A/C light turns on the windows defog, then I switch it back to recirc. From what I can see the heater core looks a little too small for the rig. I was toying with putting in an aux heater in the cargo area but decided not to as those really cold days are few and far between out here, so I got one of those little 12 volt heaters off of EBay And it seems to do what I need.

maybe its got the wrong thermostat...or no thermostat. i.suggest checking vacuum, thermostat, and flush the hell out of it. also very important-get the air out of cooling system! either burp it the ole fashioned way or use a bleeder valve.if it jas one.

Have you ran a system check on the HVAC system? You will have the typical blend doors codes, but if you get more than those it is possible the fresh air intake door is stuck full open so your pulling 100% outside air. Might be worth a look, if you have modded the heater then you know where the servo is and you can see it function when you turn on and off the recirc button. I think you can rule out the thermostat and air in the system, as these rigs have the backwards cooling system and any air or thermostat problems are noticed very quickly. Hope this helped.

Hello i have a jeep grand cherokee wj I checked the blend doors, I have clean the heater radiator but my jeep does not heat inside the cabin the radiator is very hot. Anyone can help me?

So if the engin is at operational temp, and the heater core has good flow both in and out but you still don't have any heat inside then the only thing it can be is the blend door that changes from Heat to A/C, do a search on You Tube and watch those that show up, I did the kit on my Grand Cherokee that did away with the dual controls so I could just use the drivers side as the main control?

Can y send me the link of this video plz

https://www.youtube.com/watch?v=kIWnuZ8vkEE There are a lot more there also.