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-   -   01 jeep grand cherokee laredo heater issue (http://www.jeepgarage.org/f203/01-jeep-grand-cherokee-laredo-heater-issue-51892.html)

Mobbin 12-21-2012 02:04 PM

01 jeep grand cherokee laredo heater issue
 
I've been having some issues with my heater not working right, my heater does not get very hot anymore and this all started right after I changed my thermostat because my jeep was overheating. I ended up taking it to a mechanic that was able to increase the heat by a little but with this cold weather it doesn't work very well. The heater core hoses are very hot when running at normal temp and i have full coolant. The heat only gets warm when I have it set to circulating too. I have the basic temp control and not the more fancy version on the other models. My car does not over heat at all anymore but this only started right after I changed the thermostat, any suggestions?

Gus9890 12-21-2012 06:48 PM

Re: 01 jeep grand cherokee laredo heater issue
 
Your blend doors may be shot

Frango100 12-21-2012 06:56 PM

Re: 01 jeep grand cherokee laredo heater issue
 
Quote:

Originally Posted by Gus9890 (Post 727655)
Your blend doors may be shot

Being the manual temp control system, there is only one blend door. Could be broken, but would be strange that it broke right after the thermostat change. It could be that an air pocket is preventing a good liquid flow through the heater core. The engine coolant temperature is reading normal?

Mobbin 12-22-2012 05:32 PM

Re: 01 jeep grand cherokee laredo heater issue
 
Yeah my car temp is fine no problems with that. Could it be possible the thermostat is a fail safe and be stuck open explaining why my car doesn't over heat anymore and my heater not getting hot?

Frango100 12-22-2012 06:13 PM

Re: 01 jeep grand cherokee laredo heater issue
 
Probably not. When the thermostat will stay open, the engine coolant temperature will go down, so you should see that on the coolant temperature indicator. Since you say that the car temp is fine, the problem should not be the thermostat.

Mobbin 12-22-2012 07:39 PM

Re: 01 jeep grand cherokee laredo heater issue
 
Okay so it sounds like its the blend door then. If I'm correct to change the blend door it requires taking my dash apart? And where would be the best place to buy a new blend door for my jeep?

Frango100 12-22-2012 09:46 PM

Re: 01 jeep grand cherokee laredo heater issue
 
Since the problem could still be an air pocket in the heater core, i would start with this: put the jeep on a slope nose up and with the engine cold and radiator cap removed. Now start the engine and let it warm up. During the warmup the coolant expands and can/will overflow from the radiator, but check if you see any bubbles coming out. Air wants to go to the highest point and maybe with the nose a bit up the air pocket can move away from where it was stuck. Be carefull NOT to remove the radiator cap with the engine hot, because the system will be under pressure, and hot liquid will come out and cause burns.
If that seems to be ok, you could have a look at the blend door actuator. It is hidden behind the glove box door. Remove the door and you will see the blend door actuator. While moving the temperature selector, watch if you can see the actuator moving. If that seems to be ok, remove the actuator and actuate the door by hand. You could also see then if hot air will come out of the vents.
Eventhough blend doors are VERY common on the automatic zone control system, on the manual system they are not. Maybe a bigger change that the actuator is the problem, but still strange that the system was working ok before the thermostat change.

Mobbin 12-24-2012 01:18 AM

Re: 01 jeep grand cherokee laredo heater issue
 
Alright I will try that ASAP and see if that works and let you know and thanks for the advice it really helps.

kennzz05 12-24-2012 01:23 AM

Re: 01 jeep grand cherokee laredo heater issue
 
might want to consider backflushing the heatercore as well
how to backflush a heatercore 01 grand cherokee - Bing

Mobbin 12-24-2012 11:32 AM

Re: 01 jeep grand cherokee laredo heater issue
 
Yeah I've already back flushed the heater core, I did it with just a hose and I didn't notice anything stuck or blocking the hoses so it didn't help at all.

JeepTechGA 12-24-2012 11:58 AM

Re: 01 jeep grand cherokee laredo heater issue
 
Are both heater core lines the same temp?

Mobbin 12-24-2012 12:41 PM

Re: 01 jeep grand cherokee laredo heater issue
 
Yes when the car is fully warmed up both lines are very warm, I can only touch them for a few seconds until it gets too hot.


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