A/C works off and on?

[01Mazda]

When I first turn on my 2005 Mazda 3, the air conditioner blasts cold air and continues for about 30-60 minutes. Then it will blow hot air. To get it going again I have to turn the car off and leave it for a few hours.

I've taken it to my mechanic a few times and of course, it works fine for him! He says that he can't figure out until the air conditioner is totally not working. What could be the problem? I appreciate your thoughts.

[shift8]

Heh same thing happens in my 2008.5. Not site problem yet though... probably condenser overheating or something... (Aka I have no idea)

[McGuyver_3]

Sounds to me like your temp sensor for the evaporator, Junction box or A/C compressor is not doing its job.
The evap temp sensor tells the computer to shut off the compressor when it drops to I think it is either 5C or 3C to prevent freezing over the evap.
I would recommend you have it scanned by a mazda dealer. That will probably have the best results
leifmadsen the condenser actually sits in front of the rad and has constant cooling

[01Mazda]

Sounds to me like your temp sensor for the evaporator, Junction box or A/C compressor is not doing its job.
The evap temp sensor tells the computer to shut off the compressor when it drops to I think it is either 5C or 3C to prevent freezing over the evap.
I would recommend you have it scanned by a mazda dealer. That will probably have the best results
leifmadsen the condenser actually sits in front of the rad and has constant cooling

Thanks for the replies & advice! I'd go to a dealer but can't afford their pricing...

[McGuyver_3]

aftermarket scanners can only go so far. im not sure how advanced mazda scanners are but I know the manufacturer I work for is rather advanced in that department.
Here is a cheap easy temporary fix. Will probably be more of a nuisance but will give you more consistant cool air. Basically manually switch on and off the ac button. You will probably have to play around with timing on your own to see what works for you. If you can, try and use another mazda 3 for best results. Start the car listen to the ac engage. Time roughly how long it engages for. The engagement is a very noticeable click and you will see the rpms raise and fall on engage and disengage. Tricky part is while driving as you more than likely won't notice it.

[jaimie08mazda3]

Check and see how the compressor runs. It's right at the bottom of the left side of the engine. It could be engaging and disengaging. From a faulty wire movin. Around. Or you could be running out of freon.

[aris]

Sounds like the condenser is freezing up..... Mine does this if its a really hot humid day and if it's been on for a while.... What I do is turn the a/c and run the blower on full and after a few minutes ice starts coming out the vents... Then I turn it back on and it works

[McGuyver_3]

Check and see how the compressor runs. It's right at the bottom of the left side of the engine. It could be engaging and disengaging. From a faulty wire movin. Around. Or you could be running out of freon.

with a loose wire, this problem would not be as consistent as it is.
low refrigerant would be a consistent no cool or half the vents being cool and the other half hot


Sounds like the condenser is freezing up..... Mine does this if its a really hot humid day and if it's been on for a while.... What I do is turn the a/c and run the blower on full and after a few minutes ice starts coming out the vents... Then I turn it back on and it works

Evaporator, condenser cannot freeze over as it sits in front of the rad

[aris]

Evaporator, condenser cannot freeze over as it sits in front of the rad

I'm pretty sure I know my car.... Even my sister in laws Mazda does the same thing

[McGuyver_3]

I'm pretty sure I know my car.... Even my sister in laws Mazda does the same thing

evaporator sits inside the heater box which is inside the car. Hence the ice coming through the vents is coming off of the evap. This is why I believe the evap temp sensor is not working properly, or the signal to the junction box is no good. Your condenser sits in front of the rad and if that was actually freezing up it would be noticeable from the front of the car and ice would never make it inside the cabin.

[aris]

evaporator sits inside the heater box which is inside the car. Hence the ice coming through the vents is coming off of the evap. This is why I believe the evap temp sensor is not working properly, or the signal to the junction box is no good. Your condenser sits in front of the rad and if that was actually freezing up it would be noticeable from the front of the car and ice would never make it inside the cabin.
Lol

car has been checked by a mechanic who also happens to be my brother who's been in the trade for 17 years

(and yes when I turn off the a/c and run the vent on full after a few mins ice does come out of the vents )