jzadovsky

Hello

I have a 2004 RX8 (obvious) 6 speed with 57K miles.

So let me start, my AC works and does not and now let meexplain.

If I start my AC with the engine dead cold, as I understandboth fans should

Turn on. In this case they do not. Also the compressor willcycle in and out

And also the pressure relief will blow if I rev the engineat high RPM.

Know if I’m driving on the freeway the AC will blow coldair, because there

Is air flow across the coils (so it does work).

I swapped the relays around and this did not work.

I topped the system with R-134, so this good.

I went through a short procedure holding 2 buttons andturning the ignition key, no help.

Now there are moments that it seems the fans turn on (in neutral)with the AC on and the car
Will run very roughly, definitely not a smooth idle.

The fans do work if the engine gets hot.

Any real help would be appreciated.

logalinipoo

It sounds to me like a control **** bad solder issue or maybe the system is overpressurized.

Do the check to make sure you get 0-16 on the control ****.

What pressure relief??

jzadovsky

Hello
Thanks for the feedback.
I am not sure what you mean on the following: :0-16 on the control ****"?
The over pressure is do to the fact there is no air flow and I assume the system is heating up.
Again, what is happening is that the cooling fans are not coming on.
The question is why
Thank you
Juan

logalinipoo

The cooling fans are not coming on because they have a logic controler that does not turn them on unless they are needed. If the ac is switching on and off due to a bad control **** then when it switches off the fans will turn off.

You mentioned a pressure relief. Do I really need to quote your exact sentence?


What are you talking about. There are no pressure reliefs on the car that I am aware you can see functioning except for the radiator cap.



https://www.rx8club.com/series-i-do-...ontrol-158200/

jzadovsky

Hello
Here is what happened 3 times, let me see if I can explain correctly.
This escape of built up pressure is happening on the drivers side on the underside
around the radiator. You can hear it and see it, so it is definitely not my imagination.

So if I understand what you are saying, you suspect my problem is in the control *****.
Can I repair it or do I need to purchase a new unit?

Thank you for the help
Juan

Colon Terminus

1st. post in this thread:
https://www.rx8club.com/series-i-do-...ontrol-158200/



I, too, am curious about this "pressure relief" valve.

kevinande

There is no "pressure relief". The fans are supposed to engage when the A/C is switched on to facilitate air flow over the condenser. It does not matter if the car is dead cold or not. Air flow over the condenser is a must to have cool air in the cabin. You are correct the reason the air works going down the highway is because you have the necessary air flow to facilitate cooling. I would start with making sure the fan(s) actually work, in particular the one on the passenger side. You can apply power directly to them without messing up anything just to see if they come on, and then trouble shoot things like relays and what not if they will not power up. If you can switch between heat and cool, the solder points on the control **** are fine. Start with the fans!

jzadovsky

Let me take a closer look at the fans, see if something is wrong there or not.
Need the weekend to look at it.

I have a question: In the RX8 HVAC system, if the pressure builds up so high that potential
of damage occurring. Is there not some sort of mechanism to prevent an explosion or damage.
I know for a fact that there are cars out there that do have a pressure relief valve.

Juan

logalinipoo

No car ac system i have ever seen has a pressure relief valve.they are sealed for environmental protection. They have pressure switches that shut it down when it gets overpresures.

Ours is right on the side of the radiator fill tank.

FinsteRX8

Almost all AC systems I've seen have some sort of relief valve, usually on the compressor.

FinsteRX8

There are usually 2 pressure switcheson the high pressure side of the AC system. One will send a signal as the high side pressure increases to turn the fans on and there should be one that shuts the compressor off when the high side pressure gets too high (before the safety valve blows)
I'm not sure on the rx8 but the high side switches are often combined into one. I can try and check the wiring diagrams on identifix.

logalinipoo

I guess i stand corrected, but ill still stick with i've never seen them.

Even if it is that poping off. Then you are loosing fluid and may be low kind of quickly. You are also looking at multiple failures. If the fans arent working then the high pressure switch should shut it down before the pop off blows.

Diagnosing a problem like this is much easier with a proper set if gauges. That way you can see if it's overpresured.