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AC NOT COOL (AFTER 9/11/03 PRODUCTION)
Applicable Models
Model Starting S/N Ending S/N
2004 RX8 40118171 ********
Some customers may complain of lack of AC cooling from the vents. This may be caused by the intake air selector (recirculate / fresh) in the "FRESH" mode. Cooling the interior of the vehicle may take longer if the air intake selector is in the "FRESH" mode. Maximum cooling is achieved when the intake air selector mode is in the "RECIRC" position. The AC amplifier can be programmed to automatically default to "RECIRC" mode when the following conditions are met:
1. Ambient air temperature is 68 deg. F or higher.
2. HVAC control mode is in "FACE" mode.
3. HVAC temperature is in maximum cool setting. Customers with this concern should have their vehicle repaired using the repair procedure. NOTE: Vehicles produced before 9/11/2003 are not programmable and should have the AC amp replaced per Service Bulletin # 07-002/04
1. Verify concern.
2. Verify ignition switch is in OFF position.
3. Press and hold the front defrost and air intake selector buttons simultaneously.
4. Turn the ignition key to the "ACC" position for 3 seconds. (Continue to hold the buttons down from step #3.)
5. Turn the ignition key to the "ON" position for 3 seconds. (Continue to hold the buttons down from step #4.)
6. Successful programming will be confirmed by the rear defrost indicator light flashing 3 times. NOTE: If vehicle's battery dies or cables are removed, the programming will not be retained and must be performed again.
Thank you for the rest process. I will post tomorrow after I get home from work.
It is supposed to be record highs tomorrow. What better way to test the rest then in 108 to 110° heat.
1. Grab a factory service manual around here. The S2 one has a section where you can check if your A/C is working correctly by waiting until the A/C cycles on/off, then holding the throttle at a constant RPM and checking the temperature coming out of the vent. All you need is a meat probe to test it out.
2. The compressor in our cars is admittedly a bit underpowered. With the 4-port engine and the autotragic, this probably becomes an even bigger problem. The AT like to hold the RPM way too low for its own good. You probably want to shift into M and use the paddles to make sure the RPM stays at 3k RPM when cruising.
Thank you for the rest process. I will post tomorrow after I get home from work.
It is supposed to be record highs tomorrow. What better way to test the rest then in 108 to 110° heat.
I'm in Phoenix with not sunshade at work or home. Trust me, I feel ya.
I h ave a fully functioning a/c system in my 04 and i will say when the temps are in the 90's the a/c isn't terribly effective. Its cool but not cold. I recently serviced the a/c system and did a full evac and recharge, vacuum, added oil etc. When the temps are in the 80's the a/c seems ok. I remember when I bough an 05 new that the a/c wasn't great when it was really hot out either, but it never blew warm. It was always just adequate but not enough to freeze me out.
I would get the car back on an a/c machine and check line pressures. A high low side pressure can indicate a blockage. You want to see somewhere between 30-55psi here.
A clogged condenser can also cause poor a/c performance. Visually looking may not be adequate. You may have to remove the lower tray and check to see if there is anything trapped between the condenser and the radiator. It would also be a good thing to wash the condenser with clean water to remove any sand or dirt that's built up in the fins.
I would then do an evac and a good 15-20 minute vacuum on the system and then recharge. I believe that the RX-8 take near a pound of R-134 and an ounce of oil should do the trick.
They also sell a special cleaning agents for AC condensers (its technically for residential AC units, so use at your own risk on a car's condenser), I've used it on other cars with no issues - ideally you want to rinse it out from the back side so the dirt doesn't get pushed in deeper.
So this one is a bit controversial but it's quick, cheap, and doesn't hurt anything. Use self-adhesive pipe insulation and maybe thermal wrap to wrap the low-pressure(?) A/C line near the top of the firewall in the engine bay. Some folks say it helps by a few degrees, others say it doesn't. Either way it's like $6 and 15min of your time to do it. Might help. Here is a link:
EDIT: Pic shamelessly stolen from the thread, not my 8.
EDIT 2: If you haven't checked already, there is also a DIY on cleaning/replacing your cabin air filter. Assuming you are recirculating the air, this may be contributing to the problem.
So this one is a bit controversial but it's quick, cheap, and doesn't hurt anything. Use self-adhesive pipe insulation and maybe thermal wrap to wrap the low-pressure(?) A/C line near the top of the firewall in the engine bay. Some folks say it helps by a few degrees, others say it doesn't. Either way it's like $6 and 15min of your time to do it. Might help. Here is a link:
EDIT: Pic shamelessly stolen from the thread, not my 8.
EDIT 2: If you haven't checked already, there is also a DIY on cleaning/replacing your cabin air filter. Assuming you are recirculating the air, this may be contributing to the problem.
There is nothing controversial about this procedure if you know how air conditioning works. This procedure is just plain useless and may actually do more harm than good. Saying it does not hurt anything may not be necessarily true, here is why. The suction pipe "the fat one" is supposed to be a gas on it's way back to the compressor. The "cooling" has already taken place inside your car over the evaporator. It then moves down that exposed pipe to the compressor. That exposed pipe aids in the transfer of heat "turning your liquid into a gas" so the compressor only compresses gas and does not attempt to compress non compressible liquid. When you insulate the pipe you effectively limit heat transfer and make it possible for liquid to enter the compressor....not a good thing. The problem with the RX in particular is that the condenser is undersized and R134 is not a very effective refrigerant with that size condenser coil. Its just a reality with the limited space in the engine bay. So those few extra feet of exposed pipe are your friend. The best you can do is keep the condenser clean and clear of debris and make sure your under tray is in place to direct air flow over the condenser when at speed. So to the OP Don't do this.
I don't want to hijack the thread so I'll just reiterate, the above process is controversial. Cleaning/replacing the cabin air filter is just good practice.
I'd think if you were to wrap insulation around anything it would be from the condenser to expansion valve and expansion valve to evaporator (I.e. the small high pressure lines) that is the point where the R134a has been compressed and cooled and you'd want to reduce adding any heat to it so it has the maximum cooling effect when it expands and drop pressure and temp before hitting the evaporator.
Cooling the return line to the compressor is akin to cooling the intake pipe to the turbo, no real effect, the pipe you'd want to insulate would be between the IC and TB (condenser and evaporator in AC terms). Pointless to try and insulate anything before it enter a compressor and increases in heat.
I don't want to hijack the thread so I'll just reiterate, the above process is controversial. Cleaning/replacing the cabin air filter is just good practice.
Allow me to reiterate as well. The only reason its "controversial" is because people who don't understand how air conditioning works are making recommendations on how to modify it. Encouraging others to do something you dont fully understand is irresponsible at best. Learn how tbe process works and then recommend modifications.
07-16-2018, 10:07 PM
