My ac sucks

[flcruising]

Negative DKaz. The wife said she noticed that the car became cooler much faster and stayed cool even in traffic (that has always been my biggest gripe...air warms when idling). Basically, the AUTO climate still modulated the blower motor, it just reached the preset temperature quicker.

 

[flcruising]

I finally had a chance to 'experience' the improvement this past weekend, and I must say that it wasn't that noticeable. I think I'll swap out the 50k resistor for a pot so I can adjust this to the threshold of evap freezeup. 37k, like billm used, may be better.

Why couldn't Mazda have just stuck with pressure switches?? My Mitsu cools sooo much better than this thing.

 

[gfdtmaz5]

I don't know if this is related but with days being around 28-34 C, the centre console (presumably where the climate control stuff is located) gets really hot down by the legs, particularly on the passenger side where the plastic cover is actaully HOT!
I took the lower right panel off and there's 2 metal channels which I can't touch when hot. I would think these to be the heater box channels from the engine coolant.
I don't know if this is normal for a 2008 but it's the first time I've noticed in 3 summers.

It contributes significantly to the cabin heat!!!

 

[DKaz]

Hey guys I noticed another problem...

I ran a bunch of tests yesterday on my Auto Climate Control system... outside temperature was 23C (73.4F) and after sunset so no sun (Mazda 5's ACC uses a sunlight sensor), my handheld industrial temperature meter read 24.5C inside the car (76.1F).

When I set the temperature to 24C, the heater turned on! So I think that the the interior temperature sensor thinks the cabin is cooler than it actually is, by 1 to 1.5C.

Full results (measure supply air temperature with a Laser/Infrared Temperature Sensor)

24C - could not read supply air temperature but heater was obviously on, foot vent mode, 1 bar, recirc off.
23C - 23C S/A temperature, upper and foot vent mode, 1 bar. recirc off. Conclusion: A/C compressor not on, blowing untempered outside air.
22C - 18C S/A temperature, upper vent mode, 1 bar, recirc off. Conclusion: Either A/C compressor is running at first stage or it's mixing tempered with untempered air.
21C - 10C S/A temperature, upper vent mode, 1 bar, recirc off. Conclusion: A/C compressor full on
20C - 10C S/A temperature, upper vent mode, 2 bar, recirc on.
18C - 10C S/A temperature, upper vent mode, 3 bar, recirc on.
16C - 1.5C S/A temperature!!!, upper vent mode, 3 bar, recirc on. Conclusion: I checked the S/A temperature like a few dozen times, it averaged between 0C and 3C.
15C - 1.5C S/A temperature, upper vent mode, max bars, recirc on.

General conclusion: I think the interior temperature sensor is sensing the car as being 1C to 1.5C cooler than it actually is.

 

[mpvue]

Hey guys I noticed another problem...


General conclusion: I think the interior temperature sensor is sensing the car as being 1C to 1.5C cooler than it actually is.

pretty tight tolerance I'd say, better than the thermostat in my house!

 

[Robotazky]

I don't know if this is related but with days being around 28-34 C, the centre console (presumably where the climate control stuff is located) gets really hot down by the legs, particularly on the passenger side where the plastic cover is actaully HOT!
I took the lower right panel off and there's 2 metal channels which I can't touch when hot. I would think these to be the heater box channels from the engine coolant.
I don't know if this is normal for a 2008 but it's the first time I've noticed in 3 summers.

It contributes significantly to the cabin heat!!!

LOL, I noticed that piping when I changed the cabin filters and thought nothing of it until I read your comment about the cabin heat. I can drive around with the windows down and feel heat down there. It drives me nuts. That's gotta be what it is. Wow. Learn something everyday on here. I wonder if they can be insulated or something.

 

[flcruising]

Get you one of these - http://shop.advanceautoparts.com/we...LUE3-_-VALUE4&ci_src=14110944&ci_sku=15490012

Or these - http://www.lategreatchevy.com/index...r+Control+Valves+and+Controllers-_-563685-_-X

 

[Robotazky]

Do they just stop flow to the heater core? I just want an insulating barrier of some type, I think.

 

[flcruising]

Yes. A heater core bypass valve. You should google it as there is really nothing but excellent results in the summer. The problem with our system is it is electronically controlled. The common vacuum bypass valve would have to be adapted to work with a solenoid actuator and manual switch. Or I've seen simply a brass plumbing ball valve if you don't want to make it sophisticated.

A 10* temperature drop with the a/c operating is not uncommon. I'd do it if I could make it clean and more seamless.

http://mymiata.paladinmicro.com/MiataHeater.htm

 

[Robotazky]

Crazy. I'm going to have to look into this when I get more time this winter. That has been driving me nuts trying to figure out why the heat was seemingly coming out of the dash, but not the vents.