mattjet

its an 04, manual, with little over 38k on it.

deputydog

Its covered under theoriginal 5 year 50k bumper to bumper. It is the heater control module, behind the radio.

There si also a service bullitin for the AC amplifier which is located under the steering column that is essentially a recall. When this thing goes bad your ac/heat temp will vary up and down.

What year is your car and how many miles? I would find a Mazda dealer as noone else seems to know jack about these cars.

mattjet

thats exackly how i feel. this car is a delicate beast, and it requires special attention. I'm so afraid that when i go to the dealer they're going to charge me some nice cash, and i don't have $600 to spend on a new unit. Are you sure the warranty covers it??

deputydog

Its an electrical item and not the harness. Warranty covers HVAC controls and devices so yea. Its covering mine. They just replaced my Heater control module, ac amplifier and are now replacing the whole radio/display section under warranty. I figure its almost 2 grand is parts.

If the dealer you are at wont do it find a Mazda dealer. You even get free loaner car with the warranty so no reason not too. I got to sport a Mazda Tribute most of this week. Maybe next week Ill be in a Mazda 5, woo.

mattjet

you have lifted my spirits. I feel a little better now. I'll see what this dealer will tell me today but i doubt it will be anything i want to hear. I have a feeling that he'll try to make me pay for the repair so i'm not going to deal with that now. thanx a million dude. going to pick up my baby today and see what the mazda dealer will tell me tomorrow.

thanx again, feel so much better now.

bigireland

dangit.. i now have the same problem.. checked my radiator fluid, was fine.. no more warranty either.. i want to complain way more but even with no heat, i love the crap out of my car.. now where did i put that $600?

zoomalot

Are these HVAC problems showing up in the later model years such as 2007 and 2008? Most reports seem to be for 2004 cars. We would hope that running improvements of some kind have been made. This is all very annoying, to say the least, to find in any modern car. I think the HVAC system in the 8 is generally weak and should be improved (maybe it has been). Customers shouldn't be stuck with bills to pay for known system design flaws. Have owners with automatic climate control (ACC) seen the same problems?

Wingnut

(2004 MT) I had the always 100% cold problem which I could only get it to provide heat if I held the **** down. Last winter I could leave it in a particular position and it would go to heat but this fall I have to hold it for a burst of 100% heat.

This led me to believe that is was a loose connection/solder joint in the control **** potentiometer. Of course you have to replace the whole heat/ac control unit to replace the **** potentiometer. I pulled it apart today and verified the loose connection with a multi-meter and re-soldered the three connections from the **** potentiometer to the circuit board, put it back together and all is well.

Front of Heater Control Circuit Board

Front of Temperaturer Control **** (3 connections noted)

Back of Heater Control Circuit Board

Back of Heater Control ****

3 Bad Solder Joints (Note cracks) Prior to Re-soldering

I did the power-button/up scan combination to get the head unit to display the dial position and it now travels even increments from 0 to 16, instead of jumping from 0 to 16 when pushed like before. I did take some pictures of where I soldered just in case it actually worked and somebody wanted to try it instead of spending $250 on the new part. As far as soldering goes, it is about as easy as it gets, there are only three signal connection to the circuit board which are easy to get to. If you were going to replace the part yourself, what do you have to lose since you will already be doing almost all the same work to get the old one out? Maybe four more little screws and a few plastic clips.

This is a repeat of a post I made at this thread, https://www.rx8club.com/rx-8-discussion-3/c-only-blows-hot-air-88075/ but I wanteed to get the word out that it is repairable.

nichelle

Just got my RX8 and I do not have heat. Where is the heat I am taking my 04 RX8 to the dealer on Monday. Does anyone have any suggestions? Please let me know something its getting cold in NC. in the morning.

Wingnut

It is most likey the heater control unit. This is the part which has the AC/heat control buttons and *****. The easiest way to verify this is to turn on the radio, press and hold the power on/off button and press and hold the scan-up button for a second (full second). The word AC should appear on the left of the display and a number from 0 to 16 on the right. I suspect yours will have the number 0 displayed no matter where you turn the temperature control ****. If this is the case you could turn the temp. **** to full heat and see if it goes to 16 after pushing down or to the right on the ****. If the number moves evenly from 0 to 16 as you turn the temp. **** then you have another problem. The replacement heater control unit retails for $350 from Mazda and I would presume at least an hour of labor (most likely more). For the DIYer the part is less than$250 from some of the dealers who sell parts and advertise on this site. I was able to take mine out and solder the loose connections to fix it.

syntheticdarkness

iTrader: (7)

I've had the same problem except that mine no matter what way you turn it it is always cold then after so long it will blow heat for a few minutes and right back to cold. I will try to use that pic to fix it, but how do you get it out without breaking anything. Sorry if it might have been on the thread, but I could only read so much . thanks for all the info.

gaximus

I had the same problem. I did the "power" + "scan up" button test. I was only getting zero unless I pushed on the **** real hard or wiggled it. I took the controls out and re-soldered it in accordance with Wingnut's post. I works perfect now. All you need is some basic soldering skills and some patients(getting out the bolt under the steering wheel ) Thanks Wingnut

Wingnut

I'm glad I was able to help at least one owner avoid a frosty and bitter winter. In case anyone else wants a slightly more coherent idea of what is involved in the repair I put together a hasty DIY at:
https://www.rx8club.com/showthread.p...31#post2675231

Good luck.

syntheticdarkness

iTrader: (7)

THANK YOU, I've got everything done and the heater works great now, and it saved us tons of money also. It was real easy to take out of the dash and put back again. THANKS AGAIN.

stickyRice

Wingnut: Many, many thanks from Lynchburg. Three drops of solder... I don't even know how to solder, lol. Saved me $hundreds. Excellent DIY.

MX6_2_RX8

Put me on the list of people with bad heater *****. Verified through the radio technique. Still under an extended warranty so I'll have them fix it, otherwise, I'd be taking it apart. Thanks Wingnut!

MAZDA: Are you listening? This should be a TSB! I told the F$#%n dealer exactly what I did to diagnose it and they still had to see the car to order the right part. I guess I'll need to go in twice.

zoomalot

DIY is fine, but this is a widespread problem that Mazda should address through a TSB or some other means to correct the problem for their customers. It appears to be a manufacturing defect.