Forgive the stupid question, but you did make sure that all the duct work is connected/ not broken or cracked right?

 

Yes, all ductwork is in place and working as it should.

 

Be advised that the 2.4l engine has TWO thermostats--either one could be sticking and causing weird problems. Flushing the heater core--and if you feel there was satisfactory flow, it should be OK. Also, the older ductwork can come loose, especially if someone has done modifications and additions to the wiring. Good luck with your search and be sure to post your fix and findings on this forum. Many of us have over your mileage without any major problems of any kind, so hang in there.

 

FYI: The factory service manual states that when idling at normal engine operating temperature, with temp control/blower control on high, the air output at the floor should be between 130F and 136F (ambient 60F to 90F). No readings given for ambient below 60F.

Check my private message to you (Gweigel).

 

My first thought was that you've got air in your system, i.e., your coolant level is low. That however would likely find your engine running very hot -- meter well past center or even to the top of the gauge. Figuring you know how to drain and refill, I like Jack's idea.

I don't know where you live but if its seriously cold (below zero F) your engine may be putting out all the heat it can. I notice when its really cold, if I run the heater on high it actually will lower my engine temperature. These are small engines with a pretty big interior to heat up. Due to pollution regulations, the engine is programed to give its own temperature priority.

I see you're new on here. Welcome! Please drop by the newbie threads and introduce yourself to the others.

 

I would be curious as to what the coolant temp is doing at idle, ie, is the temp dropping through the whole cooling system. If it does drop it could be a thermostat issue. But if temp is good then I'd suspect the water pump impeller is worn and not providing enough flow at idle.
And why do we still call them water pumps anyways? Should be coolant pump, or circulating pump. WTF people!

 

And why do we still call them water pumps anyways? Should be coolant pump, or circulating pump. WTF people!

Its the same reason we drive on parkways and park in driveways . . . :wink2:

 

Jeep Mechanic Input Wanted

Do we have any Jeep Mechanics that could weigh in on this topic? I was curious about what issue they see more often - water pump or heater core. When I mentioned it to the service writer at the dealership, he said, "Yeah, we see a lot of those," but had no input on the fix. It sounds like a common problem, but I'm not seeing a whole lot on the web about it. I did read one thread about replacing the core by cutting the aluminum tubes, removing core and reinstalling with heater hose. Thus saving the labor of removing the entire dash and evacuating the AC system. Thoughts on that option?

 

Do we have any Jeep Mechanics that could weigh in on this topic? I was curious about what issue they see more often - water pump or heater core. When I mentioned it to the service writer at the dealership, he said, "Yeah, we see a lot of those," but had no input on the fix. It sounds like a common problem, but I'm not seeing a whole lot on the web about it. I did read one thread about replacing the core by cutting the aluminum tubes, removing core and reinstalling with heater hose. Thus saving the labor of removing the entire dash and evacuating the AC system. Thoughts on that option?

Not a "jeep mechanic", but I am an aircraft mechanic that got my start working in auto garages. Water pump replacement is far more common than heater core replacement.
That said most water pumps are changed due to leaking seals or bad pulleys/bearings.
It is less common to change one due to the pump not moving enough fluid. And, in those cases it is usually because the pump was "cavitated" or run without fluid in the system. And if that is the case, then the pump is usually not the only thing your changing....

 

To date I have done the following: Flushed the cooling system; replaced coolant with Zerex HOAT; replaced water pump; replaced v-belt; replaced v-belt tensioner and idlers; verified that all actuators are working properly - blend, vent selector, and recirc; replaced heater hoses and reversed flow on the heater core; did a 24-hour static vinegar fill on heater core; did a pond-pump citric acid flush for 24 hours too. I STILL have issues with heat. Both heater hoses are hot to the touch and flow seems good through core. Outbound hose is slightly cooler - as expected. Heat is better with recirculation on (w/o AC) and equal on both driver and passenger sides, just not very hot out the vents. I'm at my wits end with this issue and REALLY don't want to replace the heater core - even with the "cheat" method on this site. I am afraid of leaks using rubber hoses on smooth tubing (no swage). I'm thinking of strategically drilling small inspection holes in the vent system and using my video scope to see if there is some sort of physical blockage on the core face or in the vent system itself. Although, the air flow does not seem to change unless I put the system on recirc - so this seems unlikely to me. The factory service manual puts core replacement WAY on the bottom of likely culprits for heat loss. Thoughts or suggestions?

 

If both hoses are hot, you are getting flow through the core. At that point, the most likely causes would be a blockage in the ducts, or the fan speed not being correct.
Does the fan steadily increase in speed at each setting? In my Patriot with the fan on high you would have a hard time having a conversation in the front seats... Does the issue change at different fan speeds?
I would lean more to a blockage or leak in the ducts. Does it get better if you remove the cabin air filter?

 

Yes, the fan operates at different speeds as it should. In fact, the higher the speed, the cooler the air from the heater. I have changed the filter and tried to inspect the housing with a mirror. I did not notice any blockages at that time, but had limited visibility. I will do again with my scope. I have not run the system with the filter out. I will have to try that too.

I was also wondering about the likelihood of the core only moving SOME of the coolant through - like the back half (opposite of the coolant lines) were clogged or restricted in some way. If that were true, the core would appear to flow freely during a flush, but the vinegar and citric acid would have a tough time getting where it was needed to clean. Right?

 

Your post indicates you have the factory service manual? To my knowledge, Patriots don't seem to have a history of heater core plugging or failure, but you can never assume anything.

You state that both the inlet and outlet heater core hoses are hot -DangerAaron thinks you are getting flow through the core, but you are still pursuing a plugged heater core. Could you splice a piece of clear hose into the heater core outlet hose with barbed connectors and visually verify proper flow.

The FSM list these things to check for 1.)obstructed coolant flow: Low coolant level ,Inoperative water pump ,Inoperative thermostat, misc. hose problems, and plugged heater core.

If coolant flow is verified, the FSM recommends checking 2.) mechanical issues: Obstructed cowl air intake , obstructed heater system outlets, inoperative engine thermostat, inoperative blower motor system,, inoperative A/C-heater control , inoperative blend door actuator, inoperative, obstructed or improperly installed blend-air door (Actuators work but blend door is broken, stuck, etc.)

Maybe my bold items have slipped past your diagnosis?

Barring no mechanical issues, the FSM suggests checking 3.)temperature control: inoperative A/C-heater control, inoperative blend door actuator, inoperative, obstructed or improperly installed blend-air door, improper engine coolant temperature (thermostat(s)???

Diagnostics is one of my worst skills. I tend to get a mindset about what the problem is, put on "blinders" to all other possibilities, then start changing the wrong parts. I would follow the path of the FSM and verify each possibility down the list before replacing parts. For instance, the FSM has diagnostic procedures to verify the water pump is circulating fluid o.k., maybe saving you that time and expense.

 

Thanks Treegrower. I do have a shop manual and have been through the troubleshooting measures a few times. Some I have glossed over thinking they are not likely culprits. Maybe my mistake to make assumptions. I do like your suggestion of splicing a piece of clear tubing - I didn't think of that. I have since checked the ductwork and found no obvious issues. Air flow is equal with AC or heat and with or without the filter in place.

I have verified that the blend door actuator is working while parked in my driveway. I think I will remove it and check for any obvious damage to the gears, etc. Maybe it is weak and partially closing when the fan is increased. No other ideas really.

As far as me revisiting the heater core, I was merely trying to come up with a scenario where coolant would appear to flow normally yet NOT heat the interior. It would seem that the design of the core would allow for it to plug more easily at the far end where flow is reduced. As the core plugs from that end toward the inlet/outlet the heat output would be reduced due to loss of surface area while both hoses remain hot.

 

Question for you all. I noticed that often when driving the Pat the temperature gauge climbs quickly (1 mile or so @ 72F) to about the 1/4 mark and then kind of hangs there for 4-5 miles or so before climbing the last 1/4 to the 1/2 mark. I have yet to drive it in MN winters so have no reference for cold weather yet. Driving at higher RPMs makes the final 1/4 of the temp gauge go a bit faster, but not like my other vehicles. I know this thing has dual thermostats. I am wondering if the secondary is malfunctioning. Does this rate of warm-up time seem normal to you? To me, it seems slow.

 

Engine temp gauges are usually kinda dead in the middle, it keeps people from freaking out when it runs a little warmer than normal. I don't watch my gauge like a hawk but that doesn't sound very unusual to me.

 

When you get to the winter weather you may notice that running the heater keeps your engine from ever getting even to the middle of the gauge. I've noticed that on cold winter mornings when the engine has appreciable heat (say 1/4 way up the dial) and I start the heater, the gauge drops and never gets to the middle unless I lower the fan speed. Too much sub-zero air is more than a small engine can compensate for. If I let it get thoroughly warm it will maintain its heat if I keep the fan on the middle speeds.

 

Have you ever tried a cold-front or the old cardboard-front in the winter?

 

I hate reading threads in the forums that don't have a resolution. So, here it is. With winter coming and my daughter driving the car, I decided to replace the heater core. Last Saturday I gutted the interior and replaced it. Heat works wonderfully and almost instantly upon startup. I dissected the core trying to find a "smoking gun" to no avail. There was debris in the cooling tubes that was causing the obstruction(s), but I was unable to determine the cause. Car apart and back together in 6 hours.

 

Newbie here,same problem,tried everything,in all these posts to no avail,must be heater core restriction,but at the same time my heat Guage never goes above 1/4, replaced thermostats,flushed everything,actuators,still poor heat,I,m stumped.