Overheating due to A/c
 

Hello everyone, i own a mazda rx8 2004, manual version, for some reason when i turn on the a/c to it's full power turn the knob to 4 the engine starts to overheat, i get cold air but it overheats, i checked the coolant level which is okay but i can't figure out what the problem might be... can anyone help me??

How do you know you are overheating?

Is your coolant temp guage moving past where is normally reads or are you getting a warning light?

check for fans see if both are spinning.

What is telling you you're car is overheating? OEM guage, aftermarket gauge, Scanning device?

I always thought my car was overheating until I got a dashhawk, only to realize my car barely ever goes over 200 degrees (water temp).... So what's telling you this information?

my dash OEM guage, it goes above the middle point, could it be the water pump?

when was the last time you did a coolant flush ?

also, is your fan fully working ?

Is your thermostat working ?

I did a coolant flush like couple of days ago, the fans are running just fine no problem there, and how would i know that my thermostat is running fine? i think it is because the car stays below the mid line in the heating dash guage, till i start running the a/c to full power the car starts overheating rapidly shown by the guage in the dash!

Does it overheat while driving down the road or just if the car is standing still?

https://www.rx8club.com/showthread.p...mostat+working

Check this thread, I only read the first page but there's some information on how to test the thermostat, this member had issues similar to you.

Theres quite a few overheating threads from the past, search 'thermostat' 'working thermostat', stuff like that and a bunch of threads will pop up; that's what I did.

No the car overheats when am am driving it, whenever i turn the AC knob to the full limit, the guauge starts showing that the car is overheating it leans towards two points after the middle point, how can i know if the thermostat is the problem, or the water pump? or could be anything else, cuz pretty much the car only overheats when the AC is on full power....
Guys i really need your help, i don't want to lose another engine.....

really sounds like one of the fan isnt spinning.

its easy to know if thermostat is working.

ask a friend or relative to help.

when the car is cold, open the hood, and locate the upper coolant hose, the big one.

tell the friend/relative to start the car and warm it up, rev it to 2K rpm and keep it like that. grab the big upper coolant hose and hold it (keep ur hand/ties/whatever outa the belts, you can get urself kill/seriously hurt)

if you don't feel any warm coolant at all, thermostat is stuck closed (bad)

or you feel coolant flow in the first place and its getting warmer slowly (in the first place), the thermostat is still bad (stuck open, but rarely happens)

if none of the above, and the warm coolant feeling comes "instantly" after the coolant meter on the dash has reach 1/2 way. then its working fine.

stuck close = overheats very quickly
stuck open = take ages to warm up

Yea as said first check coolant level cold, quality of coolant ( is it good? lol), fans operation? Latest Flash or Cobb? If need thermostat order Mazmart Re-medy version.

Check radiator
 

If your car is overheating, the radiator is most likely at fault. Kindly check it.

This is the part that puzzles me. He indicates that the temp gauge moves. The temp gauge moves when coolant temps reach 232 degrees F.
But the A/C compressor gets shut off by the PCM when this temp is reached (232 F).
So what I am getting from this is that the A/C does not shut off and the temp of the A/C stays cool after the temp gauge starts moving.

Dun Dun Duuuun,, (Dramatic reverb)

The fans may be running, but I'm wondering if they are running correctly. He implied that the engine has already been replaced once, so I'm wondering of the fans were hooked up incorrectly during reassembly. I've had that happen to one of my cars before...

My 08 overheats with the AC on during a extremely heat day when I'm still. If I'm driving at high speed with the AC on on a extremely hot day then it will not overheat. It might be the themo or fans, I've changed the relays maybe they need to be changed again i don't know...

I used to have this issue, in Florida summer gets hot, the road itself may be 150 degrees.

First, make sure you have the engine under-tray installed, a missing plastic tray made mine overheat when the AC was on.

Second, I gave up and replaced the radiator, (mine leaked too) I used a 30% larger Mishimoto unit to replace the stock radiator, my new radiator fit very easy, with only small mods.

what does the engine under-tray look like, from what I see is the large plastic from the bumper to the oil tray. There is no leak from my radiator.