1996 jeep grand cherokee blower works but no heat. I flushed heater core with hot water, replaced thermostat, and water pump is circulating. Vacuum line?

There are several possible reasons why you may be experiencing cool or no heat in your 2002 Jeep Grand Cherokee Laredo after replacing the thermostat and bleeding the air out of the lines. Some possible causes could include:

1. A malfunctioning blend door or actuator: The blend door controls the mix of hot and cold air that is directed through the heating system. If the blend door or actuator is not functioning properly, it may cause a lack of heat.
2. A clogged heater core: The heater core is responsible for transferring heat from the engine to the cabin of the vehicle. If the heater core is clogged, it may not be able to transfer heat effectively, resulting in cool or no heat.
3. A faulty thermostat: If the thermostat was not properly installed or is not functioning correctly, it may cause the heating system to not work properly.
4. A problem with the water pump: The water pump is responsible for circulating coolant through the engine and heating system. If the water pump is not functioning properly, it may cause a lack of heat.

i posted as comment
we now still dont know if its ATC opted jeeps
we now know
both hoses are hot to core. 144f min.
so the damper is stuck!
only why remains.

answer the questions and we go to to
ATC
or
manual hvac pages, in the free book.

this is just a simple water to air heat exchanger
it only 2 things (Air and H20)
water hot, and flows.
the core gets hot.
then air must flow, bingo, id don't.

probly need a new heater core--get a haynes manual or library sec629 has pro mechanics series--if u get new one test evaporator and blower motor also to save labor

soun ds like heater core is plugged. did you try back flushing the system?

Get jeep up to operating temp
Turn on heater to max heat
Hood feel 2 heater core hoses goint into upper passenger side of engine compartment firewall.
They should feel too hot to hold
If it's not hot, could be 6 things
1. heater control valve is bad
2. Vacuum to heater control valve is bad
3. clogged heater core.
4. Bad thermostat
5. Bad waterpump
6. Needs more coolant (check when system is cold)

Do these things:

1. Disconnect vacuum line from control valve and feel under valve to manually move valve to open position. This should let hot water flow through core. If you now have heat inside, replace the heater control valve. Or you can disconnect the plunger on the heater control that is hooked on to the silver bar on the bottom of it. With it disconnected you can manually move it to the open position. It will always remain on.

2. When system is cold, disconnect both heater hoses going to heater core. hook up a water hose to one side of heater core and flush out any gunk. When you get done, the water should run clear. If you see lots of gunk come out, that was probably the problem. Replacement is like $20-30

3. When system is hot and engine running, squeeze the upper radiator hose (using gloves) when you release it you should feel a surge of water. Proves your water pump is working. If no surge, check thermostat. If thermostat checks good, look at the weep holes at the bottom of the water pump for traces of antifreeze. If you see a trace or stream of coolant, indicates bad pump.

4. As far as testing the thermostat, watch as your engine heats up on the gauge. when it gets to a certain point you will see the temperature rise, then lower, then rise again. This means your thermostat opened properly, cooling the system temporarily, then heated it back up. Replacement is around $5

Try these and see how it goes.

now there are several thing you need to check( since you know the blower and vents are working) start the jeep. let it warm up, sorry to do this to you, but turn on the heater. under the hood are two hoses going to the heater core, by the blower. after the jeep has warmed up, and heater running for about 2 minutes, check to see if either hose got warm or hot. If yes, bad heater core. if no, then the control valve that allows hot coolant to the heater core is bad. you can trace it if you follow the line to the engine, it is connected to a valve, and valve needs to be replaced( you can get it at the auto parts store). hope this helps you

flush the heater core its more in likely clogged. Google heater core flush.

unless you got visable signs of leakage its not heater core, but it could be pluged with sediment. take off both heater hoses and flush it both ways until it runs clear. you can also mix a little baking soda and water and pour in core and let set for a while and then flush.

Verify that the hot water is being circulated thru the heater core by letting the car warm up to operating temp and carefully touching both heater hoses at the firewall where they enter the core.  If you are sure that the water is flowing, the the blend door inside the ventilation housing is either not working, stuck, or not getting vacuum.  This door directs the air to or away from the heater core depending on the temp control knob position.  The system is activated by vacuum pressure, check all vacuum hoses from the engine to the firewall and also underneath the dash on the passenger side behind the ash tray.

Sounds like a circulation problem could be the thermostat or a water pump issue, Ive had a similar problem on my Ford Taruas a couple of years ago. I replaced the thermostat and the problem was still there,so I replaced my water pump later. During my inspection of the old pump after removal I had noticed a few of the fins on the internal part of the pump were missing. This probably didnt allow the pump to circulate the coolant fast enough through the system. After replacing the pump and thermostat my problem went away, I hope this helps.

George.