haeater core

[greyghost]

My heater core is bad do I need a heater core w/AC if I have AC in my 90 Maxima

[theTony]

Hey Grey,

First of all, OUCH! A bad heater core sucks, not only for you breathing in antifreeze, but because to replace one is a royal pain in the arse, and it's expensive. I have never heard of a heater core with AC. I have always just known it to be a heater core, period. The only thing that I have ever read or heard about with replacing the heater core on a 3rd gen Max that has to do with the AC is the discharging of the AC in order to have enough room to pull the bad core out, after you take apart the dash. I was going to mention that you would also need to remove the airbag controller since the core is behind the glove box, but you said your Maxima is a '90 so you do not have any airbags. One less thing to have to worry about.

Is this something you are tackling yourself? If so, my hats off to you. This is from what I have heard a 12 hour job, but if you know what you are doing, and are confident you can replace the core correctly, you can save a bundle in labor costs. I have heard of mechanics charging as much as $1,000 to to replace these things. A new core by itself cost around $300 I think.

I'll leave this post here for a couple or few days and see if it gets any kind of response and if not, I will move it to the Nissan On-line Mechanic section and see if anyone there can help!

[Mayhem_J30]

I'm with tony, a heater core is unnecessary for AC. Although, I am concerned that the cold AC air blows directly over the heater core coils and could potentially freeze the lines. (someone step in if i'm completely wrong) but I'm pretty sure that's how the whole system is setup for the fan to be used with the HVAC.

[Queamore]

I dont belive that the ac core goes over the heater core they are usually divided be some flaps and vents. I've worked on all kinds of cars and have about 15 years of experience and the heater core is not something that I would tackle bymyself. be careful on what you pull off. One thing at a time and make sure you keep track of were everything goes. It's important to put everything back the way it was or there will be no heat.

[Mayhem_J30]

I dont belive that the ac core goes over the heater core they are usually divided be some flaps and vents. I've worked on all kinds of cars and have about 15 years of experience and the heater core is not something that I would tackle bymyself. be careful on what you pull off. One thing at a time and make sure you keep track of were everything goes. It's important to put everything back the way it was or there will be no heat.

Thanks! I'm still trying to think of where people were having problems with freezing coolant lines when running low ratios of anti-freeze in their coolant. Maybe it was the condensor and the radiator...hmmm. I'll have to go dig that one up.

[Mayhem_J30]

Quemore,Here's a post recently wrote by Q45Tech a Infiniti Master Tech/Engineer here at NICO. Maybe this only applies to Q45's though, and this is most likely where I originally heard about the freezing core problem.

"As you see by their graphs [Redline WW] more than half the system improvement comes from using the highest percentage of PURE water......that will not allow the heater core to freeze from AC cooling blowing on it or corrosion to start because the deionized water strips the aluminum oxide film away."