I have a 2004 3 with 2L engine. My a/c has never worked well and I complained about it in my first summer. The dealership checked it out and said it was working to specs so I just lived with it. But this year I noticed it was even worse. It was basically blowing coolish, moist air so I took it in for repairs. The condenser, compressor and cooling fan were all replaced which cost me about $1500. They guy said it was all clogged up and that the cooling fan was actually turning in the opposite direction than it was supposed to. After the repairs we were told 'its blowing freezing cold air now". That was 3 weeks ago and the a/c still isn't right. After the repair it was OK (not good, just OK) but we always need to have the fan at highest and temp at lowest to keep the interior temp comfortable. I took it on a long trip and about an hour into it the vent airflow seemed diminished and we actually turned the a/c off and opened the windows and it was cooler that way(was about 95 out). After 30 mins or so we turned the a/c back on and the airflow was better but still not any colder. A couple days later I started the car and there was a groan that originated in the fan and changed pitch as I adjusted the speed from 0-1-2-3-4. I turned the fan off and back on and it didn't groan any more and hasn't since. I also notice that the air coming from the vents cycles from cold to cool and moist. It is a noticeable temperature change that I can feel with just my hand in front of the vent. It seems to be 'cold' for 20 seconds and then warms up for 5-10 seconds then starts the cycle over. It does this when I fist start the car and the inside car temp is over 100. I figure the 'cold' should be constant at this time. Also, the high pressure line is burning hot (can touch it quickly, but definitely not hold onto it) and I don't know if that is unusual?
I am afraid I will take it to the dealership on Friday and they will tell me 'that's just the way it is'. If that's the case, I will be one unhappy and sweaty 3 owner!!
Does anyone have any ideas of what the problem could be so I am educated when I take my car back in?

Chris

 

A few comments:

• Cold and Moist are usually mutually exclusive terms. Why? Because when warm moist air is cooled, it leaves behind most of its moisture on the evaporator (where the water is captured and then drains out through the firewall and onto the ground).
• The high pressure line should always be quite hot when he A/C compressor is running. Why? When you compress a gas (a gas into a liquid in this case), it gets hot.

 

I probably didn't word that properly. The air cycles from cold to 'cool'. In the 'cool' cycle I can feel the vent air warming up and becoming more humid. It keeps doing this cycle over and over at least a couple of times a minute.

 

I borrowed an air-vent probe thermometer from my mechanic friend and monitored it on my way to work this morning. It was 78 F and overcast so not hot when I got into the car. I set the fan on 4, but not on recirculate. Initially the vent temp read at 54F and then dropped to 50F and kept cycling back and forth between 50 for 20 seconds or so and then up to 54F for about 5 seconds. This continued for the first 5 minutes of the trip. I then noticed an improvement in the cold and the temperature had dropped and now was fluctuating between 46 and 50F, cycling back and forth as above. I lowered the fan speed to 2 and noticed a slight improvement in the cold which then cycled between 44 and 46F.
My mechanic friend said that proper, 'cold' a/c air should read from 38 - 46F. I am in the upper end of that range but that was only after 20 minutes of driving.

So I have 2 questions:

1. Do these readings sound normal?

2. Is the frequent cycling (I am assuming the compressor is kicking on and off) normal or am I in for more costly repairs if the strain of this cycling continues?

Please Help! I am taking the car in tomorrow and would like some insight!

Thank you.

 

I would appreciate any info asap. I have an appt at the dealership tomorrow and don't want to be 'snowed'.

 

I don't know what the temperature readings should be for a Mazda3, but the fluctuation is totally normal due to compressor cycling.

What are the readings when Recirc is engaged?

 

A couple of things. First off the AC in the Mz3 has never been particularly awesome. People have complained about high vent temps for years and always received the "within specs" argument from their dealers. Apparently Mazda addressed the high (or higher than most cars let's say) vent temps basically by raising the upper temp on their spec. So the AC can blow less cold air but still be 'operating properly and within spec'. Thanks Mazda.

Second the longer air spends going through the system the colder it gets. That means if you always run the AC on fan level 4 then it will blow warmer air than if you ran it at 3 because at level 3 the air doesn't move as quickly and can spend more time getting cooled off.

Things Mazda has done (other than give owners the run around). They introduced the AC diffuser plate..... maybe in '06. Can't remember exactly when. Basically on cars without the cabin AC filter they replaced the blank in the filter slot with a panel that had a bunch of holes punched in it. Since the air then had to contend with a holey panel vs. a wide open conduit it slowed the air and theoretically helped the vent temps be cooler. So first off make sure you have that. You access the panels from the passenger side of the front center console. You have to remove the PJB and it's mount to slide them out of the conduit. If you don't have one either get one or install a cabin air filter. The second option would be to get and install the cabin air filter as it would also slow the air flow down.

Another option you could go with is a trick developed by billm from mazda3forums. Basically you wire a resistor across the AC thermistor. The change in resistance tricks the car into thinking the AC is blowing warmer than it actually is, therefore making the car cool more. With a 33kohm resistor the change is about five degrees. Of course any time you run the AC colder it increases the chance of freezing the system up at which point you get either drastically decreased or no cooling until the system defrosts. What billm did to address this was wire his resistor on a timer that cuts it off after "x" minutes. That way the AC mod helps get the car cooler faster but then turns off once the car is cooled down.

I recently did this mod, however I simply wired it to a switch vs. a timer since the budget for the project was low. There's a significant difference in the temps I feel, and while my car still gets hot I've been much more comfortable this year than in previous ones. I generally run it for about 5-10 minutes before turning off the mod, and have only had it freeze up once after I forgot about it when running around doing errands. It defrosted in about a minute with the fan turned up and AC off. Bear in mind that I live in eastern NC and we've been having heat indexes in the 100-115 range for the past couple of months. Given that it seems like you've been having actual AC hardware problems I hesitate to recommend you fiddling with the system in a way that makes it work harder, I can just tell you I did it and it definitely helps.

Other things you can do to help out the AC. Tint the windows with a good ceramic tint that provides good heat rejection. I have 40% VLT all around which rejects about 80% heat (vs. a 20% metallized which might reject 50%). The less hard the AC has to work the better it cools. Use a sun shade when parked. The huge black dash gets very very hot, and even with cold AC blowing radiates a ridiculous amount of heat until it gets cooled off. Anything you can do to help keep it from getting hot or in cooling it down will make a big difference. When first starting the car drive around for a minute or two (or if you're parked for a little bit and it's breezy) with the windows open. Let the superheated air in the car get blown out and the AC will be able to keep it cool better. Another thing you can do to help cool the dash is to keep the vents on face only for a little while as it cools off more when cool air is running out of the dash vents. Also if you keep it on face only the front of the car gets more cool air since any setting including feet diverts air to the back seats... not very helpful when you're the only one in the car. I generally start out on face only and then transition to face/feet over a 10 minute period.

 

Thanks for the good advice. I was surprised to hear that a lower air speed would actually blow colder air, but after trying it out, I found it did exactly that. I have the windows tinted already and put up a sun shield when I park it for a while. I also run with the windows down for a few minutes to let the hot air out at the beginning of a trip.
I complained to Mazda about the fact that they did not inform me of the air diffuser 'fix' when I originally complained about the poor a/c performance....and guess what???? Much to my delight they are putting it in at no cost to me. I had to put up a bit of a fight to get it since my warranty had already expired, but they eventually agreed. I have some renewed faith in Mazda customer service!! I will let you know if that improves the a/c once it is installed.

 

I knew the A/C was one of the few complaints about the car when I bought mine and thought I could live with it. And I have for 7yrs now, but it can be annoying and a little embarrassing when others are in the car. It's been over 100*F here all summer long and even w/the "diffuser plate" installed (BTW: the TSB came out in late '04,) my A/C barely keeps up on full.
Your best bet is to keep the windows closed and the A/C on recirculate.

 

Yeah, it seems a little counter-intuitive that you'd want to turn the fan down to be cooler, but it makes a lot of sense. It's sort of the like the mind-set of giving your car less gas when you're slipping on ice or snow. You may not get that stuff in Texas Richard but it's like rain only colder and whiter and it sticks to the ground in big piles. :P Anyway sometimes less is more.

Fantastic habits, all.

It probably wasn't so much that they didn't inform you as it was that they just didn't know about it. Even when the 3 was only a year or two into being produced and the TSB list was really short most dealers still didn't know about the TSB's which had come out. Mazda generally doesn't advertise when a TSB comes out for people to come in to have something replaced.... not like a recall. That said they should know enough to keep up on them so that when people complain about a problem they know how to fix it. It's a good habit to keep up on the TSB's yourself so that when you take a car in to complain about that issue you can make sure they know about it. I usually print off a copy of the TSB and hand it to them.

Still great on sticking to your guns and getting them to do it for free for you. Don't expect a dramatic change in the AC's performance, however it's not like it will hurt it, and it may actually help a little.

If it's still not working super well then think about wiring in the resistor and see if that helps for you. Even if you went with a lower valued resistor than I used it would still trick the car a little bit, even if just by a few degrees.