Sunday, July 4, 2010

Weak A/C in the Car

So there's no new deck news for now. Away two weekends ago, away again most of this July 4 weekend and last weekend was mostly taken up with moving the lawn, very hot days, a trip to see Toy Story 3 and my little DIY car repair.

For the last couple years or so I had been annoyed by the weak air conditioning in my car. It's a 2000 Acura Integra I bought new 10 years ago. What's been happening, essentially, is we muddle through the summer with the weak A/C, and the rest of the year it's not noticeable. The hot days are here again, though, and the annoyance had returned.

I read up on what various problems would be, none of which seemed to fit. There's a part called the blower motor resistor, but if that's bad the fan wouldn't work at all on certain speeds. Certainly when the fan was turned on, it sounded like it was blowing just fine. And I had the A/C system recharged with refrigerant (aka Freon) last summer. Various rides in rental cars led me to believe the amount of air blowing out the vents in my own car was just way too little for the given fan speeds. Either the blower motor wasn't actually working properly, or, most likely, something was simply blocking the airflow.

In addition to the various message boards I checked up on I have a subscription to ALLDATAdiy.com For about $10-15 a year it gives you access to repair information specific to your car make and model. I originally signed up for my dad to get info about his vehicle, but I later added a subscription for my own car when I was doing another little repair. The info from ALLDATA was useful in getting started. It showed me, for example, how to remove the glove box, the first step in getting to the various ventilation components under the dash in my car.

Once I had the glove box out, it was at least easy to identify the parts of the ventilation system. Major parts in the pic: blower motor housing (white) at far right, then evaporator (black) at center, then airflow doors (white) at left. They're not too hard to access either, though it is awkward given the small amount of space between them and the floor. I zeroed in on removing the evaporator, for that would also give me access to the airflow doors, that part closer to the center of the car where air is redirected to the proper vents depending upon which settings you have dialed up with the dash controls. (I thought perhaps these could be part of the problem.) Although the ALLDATA info is not long on details (the step instructions simply say "Remove evaporator"), it did at least show the location of all the bolts. I eventually found them all, even making a trip to Lowe's to get an extra socket to reach one. I got as far as trying to maneuver the thing out of its place before I realized, somewhat belatedly, that I am not in any position to be REMOVING the evaporator. Duh! There's a part in there connected to the refrigerant system! In order to take the evaporator out I would need access to some specialized A/C equipment, and that really wasn't in the scope of my abilities anyway.

Sigh. So maybe I won't be able to fix this after all. At that point I did pull out the blower motor, a relatively easy operation with a few screws. I checked to see that it seemed to operate well at all speeds, then put it back. Then I worked to get the evaporator back into place and reattached. (Worth noting: screws/bolts that are slightly tricky to access are often harder to put back in than they are to remove in the first place.) As I was doing this I accidentally bumped a plastic piece of this box out of place. Uh-oh. What the heck is that thing for?

Well, this turned out to be not a problem but an amazing eureka moment. Pushing this piece a little more out of the way made it clear I had been on the right track all along. Now I could see into the evaporator, and it was full of crud! Maybe if I had searched more I would have found reference to this little hatch, but I had never run across any mention of it. This little door is just to what would be the warm air side of the evaporator coil. The cold refrigerant circulates through the coil. The air blows through there and comes out chilled on the other side. Except that as it was at the moment, not much air could get through the coil because it was so caked with dirt. (The pic shows it after cleaning.)

Now I don't know if the accumulated crud in there was strictly 7 years or so of crud or perhaps partially related to an earlier problem. You see, a few years after I bought the car, before moving to the house with the handy garage, some kind of rodent got in and made a nest somewhere in the vicinity of the blower motor. I turned it on one day back then and heard this crunching sound. The airflow definitely got weaker. I took it in to the dealer at that point (it was due for maintenance and perhaps already even on the schedule) who made this determination about the rodent's nest and supposedly cleaned it out. The airflow did improve after that, so presumably that was the correct diagnosis. After this recently cleaning, though, I wonder how thorough they actually were back then.

At this point, it no longer mattered. Using a variety of somewhat improvised tools, I was able to clean out the accumulated gunk. I used items made of plastic (a plastic putty knife, the handle to a Swiffer Duster), then eventually a paint brush, to rub up against the evaporator coil. Air conditioner coils are typically surrounded by aluminum fins that are somewhat fragile. Too much force could bend or break these, so scraping it with various metal implements would not have been a great idea.

When I had cleaned out as much dirt as I thought reasonably possible (that pile fluffs to a couple inches tall as well as taking up that much space on a paper towel, and that's not quite all of it), I moved the hatch door back into its place on the evaporator box and fired up the blower. Whoa! The airflow was akin to some of the newer cars I had driven recently as rentals. It worked like new, or pretty darned close. I had to wait until the next day for the real test, though: how it would cope with the hot sun. I needn't have feared, as it worked just fine. This dirt was the entire problem. After this cleaning, the A/C could now cope perfectly well with the hottest days, even after the car sat a couple hours in the hot sun.

In a newer car, this scenario is probably no longer too likely due to the advent of cabin air filters. Indeed, the hole where I cleaned the dirt out looked suspiciously like it was designed to take a cabin air filter, yet no cabin air filter is specified for my car. The mounting position may make it difficult to get a filter in there. The support where the passenger side air bag is attached gets in the way. I thought about trying to wedge a filter in there, but for the moment I'm just enjoying the properly working air conditioning.

If weak A/C airflow has been a problem in your car, I recommend you check the cabin air filter or the evaporator for accumulated dirt. Anyone modestly handy should be able to do this themselves, but it shouldn't be too expensive to have a repair shop give it a try. Just don't let them convince you you need a new evaporator until you've tried cleaning it out first. Putting in a new evaporator would certainly cost a few hundred dollars. This little cleanout cost me a few hours of time and a few bucks for a tool I didn't actually need. ;-)

Posted by Greg

2 comments:

JAYNE said...

HEY WILL HAVE TO GIVE IT A TRY, AS MINE IS DOING THE SAME THING, N WHEN I TAKE IT TO MECHANIC HE JUST SEEMS TO MAKE IT WORSE N CHGS ME A FORTUNR. IT IS RIDICIOUS HOW THEY RIP YOU OFF! !! THANK YOY FOR THE TIPS. WE NEED TO HAVE A WEB SITE FOR ONES WHO GET SCREWED BY THERE MECHANIC. I HAD A 74 OLDS GOT TIRED OF GETTING SCREWED SO I TOOK A MECHANIC CLASS AT MY DAUGHTERS HIGH SCHOOL N HIT 2 BIRDS WITH 1 STONE COULD KEEP N EYE ON HER N TAKE CLASSSES. BUT THE I HAD BACK SURGERY N THAT ENDED ME WORKING ON MY CARS I APPRECIATE PEOPLE LIKE YOU FOR YOUR HELP :-):-) ALSO YOU CAN USUALLY GO ONLINE IN CK YOUR MODEL OF YOUR CAR AN GET A SERVICE MANUAL THIS WAY IT GIVES YOU INSTRUCTION ON MOSTLY EVERYTHING, IT HELPED ME OUT ALOT. THE ONLY THING WITH THESE NEW CARS YOU HAVE TOO TAKR OUT HALF THE ENGINE JUST TO GET TO ANYTHING. GOOD LUCK IN THE FUTHER N WILL CK OUT MY EVATORATOR COIL IN MY 89 OLDS I HAVE.
I DID HAVE TO ASK YOU WHY DID U NOT USE A AIR COMPRESSOR TO BLOW OUT ALL THE DIRT?

THANK YOU

JAYNE
CRAZYJAYNE777@GMAIL.COM

kyle said...

looks like ill have to do some cleaning here soon. my integra blows cold, just not hard. it doesn't move enough air to keep the car cool on a hot sunny day. i guess ill go search for some dirt haha.