I have a 2005 RX-8 with 65k on the odometer. Not to make anyone jealous, but I live in San Diego and it was hot the other day so I turned on the A/C. Worked fine for a bit, but then just started blowing hot air even though the thermostat was all the way to the left on blue (cool). Turned the A/C off and then back on and it worked fine. However, now I notice that even though the thermostat is all the way on cool I get hot air all the time, regardless of the A/C being on or not. I've tried rotating the thermostat back and forth from cold to hot and back, but doesn't seem to have any effect. Full hot all the time.

I'm not sure if the the RX-8 uses a vacuum switch or electro-mechanical switch to allow coolant into the heater core, but was hoping that someone could give me some insight on how to troubleshoot and more importantly fix the problem. I'd really appreciate it.

I'm sweating in there!

Thanks.

 

have you tried resetting the a/c?

 

could be your **** is stripped. could be the control needs fixed.

https://www.rx8club.com/series-i-do-yourself-forum-73/diy-no-heat-repair-heater-control-158200/

 

The **** is definitely not stripped. Took it off and it looks fine.

RX8Soldier - what do you mean by 'resetting the a/c'?

 

then its the control. did you read the link?

he meant Re-program your AC Amplifier. like the link

right down there

 

haha
OP, just in case you didn't get that, click this link ===> A/C Amplifier Reset

 

Ahh, you mean I was supposed to read the whole thing.? With my ADD I'm lucky to get to the second sentence!

Gave the reset a try and no joy. Full HOT all the time, with or without A/C.

I started actually reading the thread and it looks like it could be the heater control unit. I'll do some more reading and try some of the suggestions there.

Thanks again.

 

hahhaha! your're welcome.

 

Not sure if you've figured this out or not but you may want to make sure all the connections are solid on the back of your head unit. This happened to me when i took a violent trip off the track. I thought my head unit was toast but as it turned out one of the connections which controls ac/heat etc had come loose. IIRC my fans still worked but the heater and A/C controls did not.

Hopefully that helps.

 

Jantzsen - where are the connections you are referring to? I'll try anything I can before having to take apart the console.

Thanks.

 

Check the heater temp control **** operation. Make sure it is switching from hot (red) to cold (blue).

Turn ignition to ON position. Turn on radio. Press and hold the radio ON/OFF button down and then depress SCAN up button. Radio display should change and display the word TEMP and a number between 0-16. 0 being cold and 16 being hot.

Rotate the temp control **** from cold to hot and the number value in the display should change.

If the number does not change during this procedure then the problem is in the temp control ****.
Try lifting upwards on the **** as you turn it. Just a little pressure upwards. See if it works then.
__________________

 

welcome to 8 posts ago E i linked him to that in post 3

 

New results - I did the 0-16 test and here's what happened:
1) Although the **** was all the way to the blue, display showed 13.
2) Turned **** all the way red and it read 16 and then decremented normally down to 0 when going to the blue.
3) Turning the **** again, it went straight to 13 (seems to be my new default).
4) Jiggling the **** I could get it to go back to 0, but a small touch would put it back to 13.
5) No amount of jiggling seemed to get it back on track to increment and decrement as I would have hoped.

I haven't driven it yet to see if jiggling the **** while running results in 'correct' behavior, but will do so this evening.

So, oh great gurus, what's the next step?

 

UPDATE:
So driving home I did find that I could get to the A/C TEMP display while driving and could watch it magically change from 0 to 13 when going over bumps. Jiggling the dial allowed me to get it back to 0 when full cold, but then stayed at 0, for a bit, even though I turned it all the way to hot.

Bottomline is that it appears to be the reostat (presuming that's the technology in there), so does that mean I need to replace the entire assembly?

 

I have that exact problem for almost a year. I didn't fix anything internally, what fixed it is a piece of leather in between the **** and the base (like a door stop, if you don't mind seeing something odd out of place)

 

 

Thanks for the tip Grace. While not pretty, it looks like a pretty cost effective solution.

 

Have you solved this problem yet?

My problem is eerily similar. San Diego RX8, late 2004 (but purchased in 2005!) and the heat won't turn off. **** is definitely not stripped.

This is the first I have looked into it so I haven't tried anything yet. I'll try it tonight when my wife gets home with it. My wife got the car for my birthday in 2005, and drives it to work every day. I'm still confused exactly how that worked out!

 

Try the A/C diagnostic; insert and turn your key to ON, press and hold the radio's ON and the scan up buttons at once. Your display window should show the A/C Level. Turn your thermostat and see if the level move from 0 to 16. Jiggle and turn, that worked for me with the leather in between to keep the contact plates inside to touch.

 

@ zweige

In your thread starter comment, you said this... "Not to make anyone jealous, but I live in San Diego and it was hot the other day so I turned on the A/C."

^ I'm not jealous, i live in Las Vegas. Today, i turned on my A/C too because it was warm and nice