A/C only blows hot air...
 

Looks like it's time to take the 8 to the dealer to look at and work on the A/C. Any thing I should look for and/or ask the service manager? I don't have the best experiences at the dealers. I have an 05, warranty should apply.

It only blows hot air even on the coldest setting?

If there's like 12 different settings for the air conditioner it's kinda like this for me
1-2: cold
3-4: slightly cool.
5-8: warm
9-12: hot

I took mine in a long time ago for some fix and it helped a little, but the air conditioner still sucks unless it's on the coldest setting. But whatever, as long as it works. :)

you can always try the following instructions. i won't promise that it will help, but it might. and its free and easy to try. made a noticable difference in my car.

a/c reprogramming instructions.
it only works if the build date is after 9/03, but it may work if the a/c compressor was replaced under the tsb. also, some of the 05 models already exhibit this behavior, so this procedure won't likely help. but it won't hurt either, so i say to try anyways.

1. Make sure the car is off AND the HVAC fan is off AND the A/C on/off button is off.
2. Press and hold the front defroster (on the left) AND air source (recirc/fresh air) buttons
3. Continue pressing the buttons in step 2 and turn the key to ACC for 3 seconds
4. Continue pressing the buttons in step 2 and further turn the key to ON (NOT START) for 3 more seconds.
5. Verify the programming update by observing the REAR defroster LED blink 3 times.
6. Release the two buttons from step 2 and start the car.

When you turn on the A/C with the MODE button set to FACE and turn the thermostat to full COLD (max counter-clockwise setting) the RECIRC should automatically engage. In addition, the amplifier should put out colder air (~ 5-10 degrees F colder and not just from the RECIRC setting) and the compressor will not cycle nearly as often (which some of us found annoying).

Note: This programming change is not persistent. If the battery is fully discharged or disconnected the procedure needs to be repeated to re-enable the settings.

another thing to check (this is for the dealer unless you know what you're doing), is check the freon level. some people that have complained to their dealers about poor a/c performce were actually low on freon when the dealer checked.

Yes, even in the coldest setting. I've never had any problems w/my A/C blowing cold air before. It just stopped two days ago for no reason. I looked under the hood and found no damage that I could tell (cosidering I don't know much).

If the above doesn't work you will probably want to see the dealer. I had to have the line that across the motor close to the firewall replaced because it had a small leak in it and the compressor was constantly cycling and blowing hot air.

look in the nose of the car, the 'radiator' in there.......is it oily or does it look wet/greasy?

Look for any damage to the fins.......could have picked up a rock or something, check to see if you can find any damage or holes in the unit......that is NOT covered by the warranty.

If you cant see anything, I would guess its an electrical problem as long as the A/C system is charged.

When you have the ac running in the car, even though it is blowing hot.....does the compressor turn on/off? can you tell if its working (the extra fans should come on/off and you should be able to hear whent he compressor kicks on/off)

Thanks everyone, however now I'm a little concern. I'll do and check all the above first before taking it to the dealer. Keep your advises coming...

I am going to guess it is a blown fuse since it happened so suddenly. Let us know what the dealer finds.

I have about the same issue that you are talking about. Mine will if I have the AC on blowing cold air it will for no reason start to blow straight hot air. This will also happen if I have the heat on full it will for no reason switch and blow nothing but cold air.

I have to move the knob from 1 extreme to the other and back again to get the temp to change back to what it was set at.

The dealer is now talking with Mazda :Freak_ani
So will see how that turns out.....

Programing instructions worked like a champ. AC now works sooo much better. I was completely infurated at always having to switch back the recirculate function on. Thanks for the tip.

I just got mine back from the dealer for that same reason. I hadnt had to use the A/C yet and the day it was hot out I turn it on and just hot air came out. Took it to the dealer and the A/C control module was bad. They had to order another and they ended up having the car for a week, and I got a Ford Fusion as the rental that they gave me.

glad i could help :wiggle:

A couple months ago I experienced the same issue as well. The a/c turned hot and stayed constantly hot no matter what setting it was on. I took it to the dealer, and like 2Xrotary, they replaced my a/c control module. Since then it has turned hot a couple random times, lasting about 10-15 seconds, but otherwise its been fine. Hopefully it doesn't screw up again...

my worst fear..
 

I tried the reprograming and it didn't work, so I finally took it to the dealer. The problem.. damage to the a/c condenser from a rock :mad: . When I did my first inspection of the condenser, I did see a small indentation, but never thought it could have punctured the condenser.

Ryan13b, thanks for the advice, but my insurance will pay for the replacement of a new condenser, minus my deductable ofcourse. I'll just have to eat the cost for the deductable. Plus, I live here in SoCal, next door to NA Mazda HQ. I'm not sure if I'm up to battling big brother.

Looks like this happens all the time in Houston: https://www.rx8club.com/series-i-tech-garage-22/local-dealer-we-replace-about-one-c-condenser-week-90542/

Anyhow, I'm ordering the RB screens and putting them on as soon as they arrive.

Thanks everyone.

AC Control Unit
 

I have the same problem with my 04 8. The dealer diagnosed it as a bad AC Control Unit and the part is on order. In the meantime I discovered that I can make the AC operational by cranking the temperature knob hard to the cold side and holding it there for 10-15 seconds. This works about 75% of the time and the cold air usually comes out for an hour or so before I have to repeat the process.

This looks like a common problem with this car. My part has been on order for 3 week now and it's not in yet.

Got a part on order for mine too. Just started having probs in the last 2 weeks. My dealer said they've had several 8's back in with the same problem and it needs a new part. They're getting stuck. Told me to flip it back and forth several times to get it working. I'm been stuck on cold air only, then on hot air only,.... can't wait to get it fixed!!! I'm getting new brakes too so hopefully, no more squealing at the stop lights!!

PS 04 model

EXACTLY! Glad to see others having the same issue. My dealer said they were ordering a new knob/unit thingy.

Though mine doesn't exactly get stuck, it switches from hot to cold or cold to hot automatically. Have it set to cold and minute later it blows straight heat. Have to do the back and forth motion to get it back to cold.

And on a hot day with cold AC blowing, it is rather annoying to have it interupted by hot arse rotary heat. Pretty much have to flip back and forth every few minutes. :mad:

got the 'straight heat' treatment last night, and it sucked too, being that it's usually 100 deg even at night! Did the AC reset trick, and it seemed to fix it today.... had been pluggin and unpluggin my HU for work on my carPC, must have jacked it up...
thanks!

-C

You need to do a search...........

Go to DIY section.......... make sure to use fire resistance hose for it to work properly.

I'll take a look Razz- good thing too, because the damn thing still has the problem I found out tonight.... it seems to be the 'need to turn the temp control back and forth fix' thing that people were talking about....

BUT, while I am here, I still think there is heat being produced even without the car running, since I have been spending alot of time in the car lately configuring my new CarPC, I can turn the fan on, and the input air still seems hotter than ambient....it has kinda cooled off here in Tucson (89 at nite) but I am just never feeling this 'cool' air at any time, driving sitting or whatever...it always seems just a little warmer than it should.... CAN I JUST PULL THE HEATER FUSE IN THE ENGINE COMPARTMENT WITHOUT ANY CAUSE FOR CONCERN? it's not like I am going to need any heating for at least another 2-3 months... THANKS

Repaired the circuit board
 

(2004 MT) I had the always 100% cold problem which I could only get it to provide heat if I held the knob 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 knob :knob: potentiometer. Of course you have to replace the whole heat/ac control unit to replace the knob potentiometer. I pulled it apart today and verified the loose connection with a multi-meter and re-soldered the three connections from the knob potentiometer to the circuit board, put it back together and all is well. :git:
http://i483.photobucket.com/albums/r...r/IMG_5235.jpg
Front of Heater Control Circuit Board
http://i483.photobucket.com/albums/r...r/IMG_5236.jpg
Front of Temperaturer Control Knob (3 connections noted)
http://i483.photobucket.com/albums/r...r/IMG_5237.jpg
Back of Heater Control Circuit Board
http://i483.photobucket.com/albums/r...r/IMG_5242.jpg
Back of Heater Control Knob
http://i483.photobucket.com/albums/r...r/IMG_5241.jpg
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/series-i-trouble-shooting-95/whats-up-heater-78457/#post2673979 but I wanted to get the word out that it is repairable.

I lost my 'cool' and took the Blue 8 to the shop, thinking I was out of coolent, turned out it was a little rubber band-like drive belt on the compressor - cost me about $85 to replace it...


The heater now seems to be acting odd - I followed the manuals' suggestion that I only start the heater with the mode showing the arrow pointing to the feet, and I got a little heat out - but I bet it is circuit board or something in the electronics! The dealer said it might cost $500 to repair the heater, so I am putting if off until it gets cold enough to really warrent the expense... this is a good thread!

I had that problem onvce and it was actually the control knob. Waranty coverd it

I have the same problem occaisionally. For me I found a retarded solution that always works.

When it's blowing hot and I have the AC on, I will move the temp to hot a couple times back and forth and then once I go back to all the way cold it will start blowing cold.

When it's blowing cold and I have the heater on I do the reverse. Works everytime. I have no idea why. Probably a faulty control.

that was exactly what hapened to mine. It was the control knob and waranty covered it

OP, I have the exact opposite problem. Since you're in Anaheim and I'm in Colorado, let's just trade cars.

mine has this problem first it started w only the passenger side blowing kinda cool air and hot air on the driver side they fixed it they said it was a faulty o ring.4 months later same thing they fixed it again they said i needed a new ac compressor so they ordered it they still havent called me but then again it's only been 3 days

If the symptom is that there is no heat and only cooling I would suggest checking out this hasty DIY I put together after successfully repairing the heater control unit. It may apply to the "only heating and no cooling" as well. The easy way to check is turn radio on, press and hold the power botton then press and hold for 1 full second the up-scan button. The display should read "AC" on the left and a number from 0 to 16 on the right. The number should change evenly from 0 to 16 in increments of 1 as you move the temperature knob from cold to hot. If it does not (most commonly stays at 0 despite knob position) then your temperature control knob has bad solder joints. See DIY below:
https://www.rx8club.com/showthread.p...31#post2675231

Good luck.

Awesome tip. ^

A few days ago I found that my temp knob was acting for the normal temp range for all settings until it got to max heat, then it switches over to max cold, and i have to cycle the button a few times back and forth before it does anything but cold air. 1 tick away from max heat keeps it fine atm.

Edit:
I did this on the way into work. going from 0 to 1, it blips to 1, but then back to 0, and doesn't move for any of them. Thanks for the tip for quick diagnosis.

going to check this out today, my ac blows hot in driver side area and cooler in passenger side.

In these cars that is a good sign you are low on refridgerant.

My a/c blows hot air when the knob is all the way to the left (max cold), and i was playing with the knob and when i put it in the middle, it was cold...weird :dunno:

With over 8,000 posts we would figure you'd know that it's not "weird" and it is the control unit's solder joints...

I'm not good with electrical issues...sorry

CHECK YOUR COOLANT LEVEL! If the level is very low, it will not allow the thermostat to open up from the initial restricted mode during startup. Eventually this will give you a check engine light. but until then, it will simply not give you any heat.

But that is a completely different system and doesn't concern the A/C.

So Idk if anyone else has had this problem but my A/C blows hot air regardless if the A/C is on or not. Cold can be maxed out and still the same issue. Even when the fan is on the OFF position it still continues to blow hot air. I want to take the unit out and check the wiring but other than that I have no other ideas of what it could be. Any ideas?

so did you even read this and do the test. What is the lowest and highest numbers you get?

Did you check to see if the compressor is actually running? There is an actual mechanical component that goes along with the little light that indicates the A/C is functioning. If it's running have your refridgerant levels checked. There is also a diagnostic test to determine if the blend door is functioning.

I actually got it to work yesterday by turning the knob way harder than you should need to the cold side. Still having the issue of my A/C blowing air when it is in the off position. I'm thinking I may take the unit out and check wiring and such.

Mine has started this after changing the radiator and one of the fans. No more overheating but now blowing hot air. Now the clutch clicks for a second then turns off. Now while parked I Rev the car to 2000 rpm and freon steamed out from the compressor a lot.

rob, you still didn't figure that out huh. You should probably get a set of gauges on it. it might have a blockage and not be flowing freon through the system so it overpressures.

Could be the heater control. From time to time, mine is on the coldest setting and blows hot air for a few seconds... until I tap it a bit and it gets cold again. Started recently. Happened 2 or 3 times for brief moments. I'll probably source a new one from the junk yard... or open it up and solder it.

Anyone found a solution for the rx8 a/c problem? Mine is not working also. Just bought a new compressor and had it changed but when I switch the a/c on it doesn't come on unless I manually go to the front bonnet where the fuses are and open fuse box, open black smal cover of the a/c relay and press relay infront with an iron (fuse tester) of side of the relay. The it clicks and forces the a/c part of the compressor to spin. I tried switchim other relays to that particular a/c relay but its still the same. Some one pls help

Have you checked the heater control know is functining. It is very common failure if 3 solder joints that are extremely easy to solder. It takes about a hour. From start to finish.

There's a simple function test for it also.

Repair video
 

I made a video on youtube on how to fix this issue by resoldering the three connection points on the ac control motherboard.
https://youtu.be/CtXJUZPz-DI

Hope this helps :)