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Pete, Technician
Category: Jeep
Satisfied Customers: 27205
Experience:  Over 17 years diagnosing and repairing automobiles various makes and models with some training and certifications.
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Poor heat when cold out, no new water pump thermostat

Customer Question

poor heat when cold out
JA: Have you checked the coolant level? Has there been any leaking from the hoses?
Customer: no new water pump thermostat coolent radiator heater core flushed 3 times and still blows warm in cold wesather
JA: What is the model/year of your Jeep?
Customer: 20002 liberty 3.7
JA: What year is your Liberty?
Customer: 2002
JA: Are you fixing your Liberty yourself? What have you tried so far?
Customer: yes i am doing the work myself. i replaced radiator thermostat water pump and coolent flushed heater core. i get heat on low blower and cold weather
JA: Anything else you want the mechanic to know before I connect you?
Customer: rough start condition and head gasket tested and passed
Submitted: 6 months ago.
Category: Jeep
Expert:  Pete replied 6 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

If you feel the heater hoses leading to the heater core with the engine hot and heater on is one hot and the other allot cooler to the touch at all?Or are they both hot or both cold/cool or mildly warm?

Let me know so we can continue,thanks Pete.

Customer: replied 6 months ago.
both hot one has less pressure then the other
Expert:  Pete replied 6 months ago.

When you flushed out the heater core did you flush on one end then the other flushing back and forth/back flushing and did you have good flow then at all coming out of the heater core?

Customer: replied 6 months ago.
i did it 3 times now back and forth both directions i have good flow both directions. i burped all the air out of the system. when blower is on mode 1 , 2 i get ok heat but 3 and 4 blow cool i checked blend door and seem to being working
Customer: replied 6 months ago.
heat also goes away when below 2000 rpms new symptom
Expert:  Pete replied 6 months ago.

Did you flush out the engine block mainly focusing on the coolant heater hose outlets and inlets to the engine or cooling components that the hoses lead to from the heater core.I have seen several issues with plugged coolant ports that the hoses connect to that will cause this issue here needing flushed through to resolve this issue.This is what it sounds like from here with a restriction since you have o.k. heat on low settings but poor heat on higher settings.This usually indicates a coolant restriction.It may very well still be the heater core as well.I have back flushed some of these before and re connected and still had issues with flow through the heater core even though the flow seemed o.k. and had to replace the heater core.

These are the most common causes for this issue here.These need to be checked into to locate which is the cause here and from there corrected but it is either a restriction in the engine block or components the heater core hoses run and connect to or restriction with the heater core still with it needing replaced even though it had good flow.The flow from the engine isnt as hard as the flow from a garden hose.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete