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05 RX-8 heater blows cold

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Old 01-04-2013, 06:53 AM
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Originally Posted by GARCIAC951
Is their a video or a better explanation on how to drain the heater core? I don't even know what hoses to pull off and drain. If anyone could help it would be awesome because the temperature outside is slowly getting colder and colder and I have to heat on my drivers side and i'm freezing!! Thanks!
+1. Taking a roadtrip next week and would really appreciate a DIY on how to fix this. Thanks
Old 01-04-2013, 07:10 AM
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its pretty straight foward. remove the winshield washer tank for better access. you will see two hoses going to the firewall iirc one is a little higher ( the one closer to the driver side) and that one is just a small hose bent 90deg upwards. the one next to is goes towards the tstat area i think. if you pull both of those hoses off the firewall the two exposed nipples are the heater core.

flush it back and forth with a hose until its clear.
Old 01-05-2013, 01:49 PM
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@200.mph I've already done it. I drained it with my high pressure water hose and I still don't get hot air what so ever on my drivers side any ideas?
Old 02-09-2014, 12:59 PM
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I'll try here first, but i did the soldering trick to the circuit board and magickly I starting having heat again,but only for like 2 minutes or until my first major stop at a traffic light. would the heater core be the problem or could it be something else
Old 02-09-2014, 01:06 PM
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I had the same problem. replaced by heater core last year. problem solved! Good luck@
Old 02-10-2014, 07:15 AM
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Originally Posted by Darkshizuma
I'll try here first, but i did the soldering trick to the circuit board and magickly I starting having heat again,but only for like 2 minutes or until my first major stop at a traffic light. would the heater core be the problem or could it be something else
Before you jump onto that, perform the A/C Temp. test:

1. Insert your key and turn it to AC.
2. Turn ON your radio, the radio have to be ON for this test to work.
3. Simultaneously press and hold the POWER and SCAN UP buttons for at least three seconds.
4. Turn the control **** clockwise, the digital display should show all numbers from "0" through "16" one by one as you adjust the ****.



A good indication that the control **** is broken will show in the test that the numbers intermittently jumps back to "0" or skips a number. The three prongs in the picture below are the ones that needs to be reinforced for the control to properly work.


Last edited by Grace_Excel; 11-25-2014 at 10:42 AM. Reason: Updated pictures.
Old 02-10-2014, 10:56 AM
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I'll try and flush the heater core, hopefully that does the trick. Replacing heater cores are my least favorite thing ever.
Old 10-21-2014, 03:18 PM
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Darkshizuma did you get your heater to work? I've done the flush twice and still does not work. Help anyone? what should I do because winter is coming up again!?
Old 10-21-2014, 03:24 PM
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The heater core being clogged would cause this.

Also if you havent done the repair that Grace Excel shows in his pictures two posts up, do that as well.

Travs
Old 10-21-2014, 03:32 PM
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I have already done the **** and it works fine. It just blows cold air in the drivers side and luke warm air into the passenger side when I set it to blow hot. I've already flushed the heater core twice and still nothing is working properly
Old 10-21-2014, 04:13 PM
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Do you really have to post in 18 dead threads?

Your heater core isn't flushed well enough, try again until you do it right. If it's flowing air that's only slightly heated that means the core itself isn't getting to coolant temperature.
Old 11-03-2014, 08:30 PM
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did you get it to work? Actually the radiator flush only cleared it out for about 1 winter. We sent back and used CLR and it worked great!!! However, the warning label for CLR says not to use it on aluminum. so we put a drop on the outside aluminum tube (stood ready with a water hose, but no reaction, so we used it.) we only let the CLR sit in the heater core for about 6-8 minutes and flushed it with a water hose so pressure would push all of the CLR out. I would NOT recommend running CLR with the hoses hooked up to the engine. we isolated it only to the heater core and flushed with water afterward for a long time. the heater worked for 3 years until he sold the car.
Old 11-11-2014, 09:29 PM
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I got to get mine flushed out also, I did it a few times and it still isn't hot, gonna have to take extreme measures I suppose.
Originally Posted by shadetreephil
did you get it to work? Actually the radiator flush only cleared it out for about 1 winter. We sent back and used CLR and it worked great!!! However, the warning label for CLR says not to use it on aluminum. so we put a drop on the outside aluminum tube (stood ready with a water hose, but no reaction, so we used it.) we only let the CLR sit in the heater core for about 6-8 minutes and flushed it with a water hose so pressure would push all of the CLR out. I would NOT recommend running CLR with the hoses hooked up to the engine. we isolated it only to the heater core and flushed with water afterward for a long time. the heater worked for 3 years until he sold the car.
Old 11-16-2014, 02:40 PM
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I have the same problem. Climate here is dropping to 30's and i can't handle the cold air in my car.. I need some heat... I'm searching to see where the problem comes from.
Old 11-16-2014, 03:20 PM
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It's probably a clogged heater core... You already found the thread...... and posted on it.........
Old 11-20-2014, 08:50 AM
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Hoses Won't come off.

Hi So I've been reading this forum for help with the Heater blowing cold on the driver side. Yesterday I tried to get the hoses off so I could flush it but the hoses have been on my 04 probably since it was built and do not want to come off. The only think I can think is to cut them off but I don't know what replacement hoses to get and I don't trust the part store to get me the right things. Can anyone help me out with the in and out hoses for the heater core?

Thank you!
Old 11-20-2014, 08:53 AM
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Take channel lock pliers, grip the hose near the end, the metal pipe should be in the middle where you grab. Twist it slowly back and forth. Make sure to grip it tightly. Becareful not to rip the hose, but if you do, you can probably cut it down and still have enough length.
Old 11-20-2014, 08:59 AM
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Thanks Hessel I'll try that not sure if it will work because it is really stuck on there but I'll give it a shot.
Old 11-22-2014, 02:08 PM
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temporary solved the cold air

I played with the temperature control **** after I had turn on the radio and pressed scan button up. It read 0 before messing with the temperature control ****, I noticed when I slightly pulled it while turning to the warmer temperature the numbers moved until I got it to 16. I had to play with it until I got to stay there, then heat started blowing. I think there's like some kind of bad connection or shortage problem. I'm going to monitor it, and hopefully on my spare time, pull then entire control unit.
Attached Thumbnails 05 RX-8 heater blows cold-028.jpg  
Old 11-25-2014, 10:53 AM
  #45  
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Originally Posted by luvbug82
I think there's like some kind of bad connection or shortage problem. I'm going to monitor it, and hopefully on my spare time, pull then entire control unit.
It's been discussed in the past, you will see in my previous post above what those "connections" look like. That trick you did will work for a few up until you go over a bump and it looses connectivity. If this is your particular issue, a quick search should yield you to this DIY: No Heat? Repair Heater Control Another issue if the control ***** work as tested, is a clogged heater core, which is also discussed in other threads related to this problem.
Old 12-30-2017, 12:12 PM
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I know this is an old thread, but hoping someone can help. My sons car is experiencing the same issue where the heater is blowing cold air. I can help him try to flush the system to see if that helps, but something else caught my eye in the thread.

It sounds like you can use the radio to do some diagnostics on the system. A few months ago, my son swapped out the factory radio for an after market version. Would we still be able to use the radio to perform the diagnostics test? Any chance that swapping the radio could be the cause of the issues with the heater?
Old 01-14-2018, 03:52 PM
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The radio is most likely not your problem. The heater core is poorly designed by having the inlet and outlet tube on the same side of the heater core. So, if the veins on the heater core clog up, the water simply comes in and goes right back out without passing through the veins. Flushing it with CLR works but you want to be careful to flush with water thoroughly after letting the CLR sit in the heater core for a few minutes.
Old 01-15-2018, 08:55 AM
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For what is worth. I noticed a problem with my heat yesterday

If you cranked the temp control too quickly from cold to hot, nothing would happen. Turn it at a normal speed and it worked fine

Also turning it all the way hot would cause it to go completely cold, even if the last click before it was nice and hot... not sure if it is the dial under the **** wearing out... but check to see if this is the case with yours... it may help you find the problem...
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