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Jay
Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 14220
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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2002 Nissan Altima: Cylinder..thermastat..water valve, and coolant

Customer Question

2002 Nissan Altima 4 Cylinder. No heat at idle. Stayed up late last night to replace thermastat, water valve, and coolant. Bled coolant system to remove potential air pockets with front bumper 22" off finished floor. Result: No heat at idle. Warm heat under motion above 1500 RPM. What do I do next? Tired in North Olmsted
Submitted: 3 years ago.
Category: Nissan
Expert:  Tim West replied 3 years ago.

Tim West :

Thanks for visiting Just Answer

Tim West :

This could be a problem with the heater core clogging up.

Tim West :

Here are a few things to try, feel the heater hoses and feel if there is a difference in temperatures.

Tim West :

If one hose is hot and the other is cold, try removing the heater hoses and flushing out the heater core using either compressed air or a water hose and see if you can clean out any obstructions.

Tim West :

If the heat gets better but not perfect, you may need to replace the heater core.

Tim West :

If both the heater hoses are cold, I would suggest bypassing the heater core and install a clear hose between the heater hoses.

Tim West :

Watch the coolant as it flows through the system.

Tim West :

If there is little or no coolant flow, there could be an issue with a water pump. If there are air bubbles in the system the system might not of been bled properly although you did the right bleed procedure with raising the front of the vehicle.

Tim West :

Can you check this first? And does this make sense?

Customer :

OK, so the possible next step is a heater core blockage? Where will I locate both heater hoses? Are they in the engine compartment on the firewall closer to the passenger side? The water pump was replaced with the timing belt not so long ago so I do not suspect this.

Customer :

If I remove the heater hoses, will I need to bleed the coolant system again?

Tim West :

Yes, the heater hoses are going to the firewall passenger side. And yes, once you remove the heater hoses you will lose some coolant, so bleeding the system again should be done.

Customer :

How much success have you seen in removing heater core blockage with a water hose / air blast? If heater core blockage is confirmed and I am unable to remove blockage, what then?

Tim West :

Then you will need to replace the heater core itself.

Tim West :

The heater core is pretty common to cause this problem.

Customer :

Is this an end user friendly operation or a dealer recommended activity?

Tim West :

It's actually a pretty big job to replace the heater core, that is why I would recommend cleaning it out. Backflushing is pretty easy but in order to replace the heater core you have to evac the freon, remove some of the dash. It's a 5 hour job.

Customer :

Given what we've discussed so far, do I understand you correctly in that the most likely possible fix to my problem is to either clear a blockage in or to replace my blocked heater core?

Expert:  Jay replied 3 years ago.
Hello and thank you for using JustAnswer.com

Did you check the air mix door gear by the gas pedal? There was issues with this on 2002 models. See image for location of gear.graphic

Let me know, thanks Jay!
Customer: replied 3 years ago.
I did not know about the air mix door. I drove my wifes car to work today and have pulled in my shop so that it is warm when I leave. I'll go look at this right now and get back to you. My gut instinct is telling me that I have a blocked heater core. I'll try the water hose treatment on that tomorrow for sure. Thanks for your suggestions to this point. I'll get back to you soon. Best Regards, Frank
Customer: replied 3 years ago.
Just went down and crawled under the steering wheel where I observed the air mix door gear to be intact.

Tomorrow I'll attempt evacuating the blockage in the heater core and get back to you to either seek more wisdom or to accept your answer.

Thanks again. Frank
Expert:  Jay replied 3 years ago.
Heater cores are extremely rare. I have never seen one get clogged. That air mix door, and air in the coolant system are the most common for no heat concerns.

Thanks Jay!
Customer: replied 3 years ago.
Dear Just Answer,
I spent the weekend flushing the heater core, topping off the coolant with a 50/50 solution, jacking the front end of the car to 24" off the floor to remove any air pockets or bubbles, and then test driving the vehicle. I still have a problem getting heat at idle. As nothing you've suggested has seemed to work so far I am unable to accept your answer. I am taking the vehicle to my local Nissan Dealer to address the issue effectively negating any productivity from your intercession. I wish it had worked out better. Best Regards, Frank
Expert:  Jay replied 3 years ago.
Sorry none of the information helped Frank. The only thing I can think of that is keeping you from getting heat at idle at this point, is either there is still air in the coolant system, or there is a restriction in the radiator. Like I said to you before, heater cores are extremely rare.

Let me know how you make out. Thanks Jay!
Customer: replied 3 years ago.
Dear Jay, You have been greatly responsive and I appreciate. I'll be happy to drop you a line at the conclusion of these reparations and let you know what I've learned. Thank you. Kindest Regards, Frank
Expert:  Jay replied 3 years ago.
Thanks Frank. I am always curious on what the out comes are.

Thanks Jay!

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