I had this problem twice; once in the summer of 2007, and again in the
summer of 2008. The reason I am writing this note is to hopefully help
anyone having a similar problem. Yes, it can be fixed. The trouble is
convincing the dealer this is really a problem.

SYMPTOMS:

- A/C is not cold enough in summer.

- Heat is not hot enough in winter.

- Small changes to temperature dial cause big change in vent temperature.

DEALER RESPONSE:

- Claimed there was a refrigerant leak. Recharged A/C for no charge (under
warranty.)

- Claimed 60 degrees is normal and A/C temperature depends on outside
temperature. (One dealer said the A/C can only cool the outside temperature
by 30 degrees. Another dealer told me the limit was 20 degrees.)

THE STORY:

In the summer of 2007, I took my car to two different Mazda dealerships
because the A/C wasn't cold enough. The first place was useless. They simply
recharged the system and then claimed 60 degrees is normal for A/C. I called
a friend's mechanic and he said A/C temp should be in the low 40's (with
cooling on max and recirc on.) I then called a different Mazda dealership
and they also said low 40's is normal, so I took my car to them. After a
full day of searching, they got my vent temp down to 43! The mechanic said
he finally found a loose wire on the "hot/cold rheostat." It worked great
after that until the next summer.

In the summer of 2008, the same problem happened again. (A/C temp no cooler
than 55 - 60 degrees.) The car went back to the "competent" dealership, but
this time things didn't go so well. The same guy worked on the car and
checked the original loose wire. That didn't work this time. So he did a
leak check with a blacklight and said there was a very small leak caused by
a bad O-ring. That was replaced and the A/C was recharged again. They said,
"All fixed." Sadly, the vent temp was still 60 degrees. When I told them it
was still too warm, they gave me the "it depends on outside temperature"
story the first dealer told me back in 2007. Sheesh.

All of this was covered under warranty which was nice, but my A/C didn't
blow cool air. On top of that, small changes to the temperature dial
resulted in big changes to the vent temp. (For example, I changed the dial
from 70 to 72 and the vent temp went from 60 to 90. Outside temp was around
70 at the time.)

THE BULL:

Outside temperature is not the problem. That's a fact. This has been proven
to me twice now; once by the second dealer fixing the problem, and once by
myself. When the system was broken, 60 degree air came from the vent with
recirc on and cooling set to max (60 degrees on my climate dial.) The
outside temperature that day was low 80s. After the system was fixed a few
days later, my vent temp was 42 degrees and the outside temp was 95. No lie!
That's 53 degrees of cooling power. (95 - 42 = 53.)

Another myth is that it is normal for the computer to increase vent temp by
20-30 degrees when you change your knob one or two degrees. When the system
is working properly, I have never seen it react more than 5-10 degrees for
each degree I change the dial. (This is assuming the car has been running
for a while.)

THE ANSWER:

I worked on cars back in the early 80's, but I don't know much about
computer controlled cars. At any rate, the dealerships ticked me off bad
enough to get me under the dash to see what was going on. The good news is
that I fixed the problem without doing anything in the engine compartment.
The bad news is I am not exactly sure what fixed it.

All the fiddling I did was behind the glovebox. To remove it, open the door
normally and press on the sides to allow it to open beyond the stop point.
There's also a safety string hooked on the right side that needs to be
removed. (Just slip it off.) After that, the bottom hinge simply snaps off.
(Pull the door toward you.)

Inside the glovebox area, you will see the access door for the cabin air
filter. Above that is a servo motor that controls the recirc flap. To the
left of the filter are two more servo motors; one on top of the other. The
upper-left motor controls whether air blows out of the top vents or the
floor vents. The lower-left motor controls the hot/cold mix. This was the
motor I was very suspicious of, especially since the mechanic who fixed this
problem the first time said it was a loose wire on the hot/cold rheostat.

I removed the lower-left servo motor and then moved the flap by hand. To do
this, I unplug several connectors that prevent me from getting a torx wrench
on the servo motor. (I reconnected them after taking the motor out.) Moving
those wires and connectors might be important, because as it turns out, the
servo motor looked perfectly fine, and moving the flap by hand made no
difference in the problem. (i.e. The air got hotter and colder as I moved
the flap, but never colder than 60 degrees.)

While the servo motor was removed, I noticed a thin black wire pair (similar
to speaker wire) running to the middle-back of the dash area. I reached back
in with my hand and wiggled it a little. It seems to go into the evaporator
part of the A/C system, but that piece is fairly buried so I couldn't
determine what the wire was for.

Since the cold air was still only 60 degrees at this point when I was
holding the hot/cold flap by hand, I reinstalled that servo motor and check
the temp again. (Still 60 degrees. *sigh* So much for my original theory.)

Next, I removed the cabin air filter and place my hand into the opening to
feel the temperature of the air flow. WARNING - CAUTION - DANGER! The
airflow pulls your hand downward into the rotating fan, so please be careful
while doing this.

I notice the air flowing through the filter box felt very warm. I turned
recirc on and off a few times and saw the flap move, but the air temp didn't
feel any different. I hit the auto mode again and then manually turned down
the fan speed. (I repeat - "fan speed," not the temp knob.) Up to that point
I was letting the computer control fan speed. My hand started feeling
cooler! I checked my vent temperature and it was dropping below 60. Finally!
After a while, I turned the fan speed up and the vent temp continued to
drop. Even after I turned the auto-climate control back on, everything still
worked.

One other possibility was that my engine was idling for around 45 minutes
during my investigation. It is possible that something started working just
because of that.

CONCLUSION:

I'm not sure what finally fixed the problem, but that's everything I did as
best I can remember. I really think I bumped a wire or connector that was
loose. Or possibly there could be something wrong with the recirc flap. That
servo motor always moved during my tests, but perhaps the flap wasn't
seating itself correctly and allowing hot air in from the outside when it
wasn't suppose too.

Best of luck to you in solving this problem. Hopefully it will just start
working for you too ... and stay working! I'm keeping my fingers crossed.

TIP:

You can buy an inexpensive thermometer for measuring vent temperature for
around $10. Mine is made by Interdynamics and is called a "Car & Home Air
Conditioner Check Gauge & Test Thermometer." I just use the thermometer, but
also comes with a gauge for checking A/C pressure to see if a recharge is
needed.