First of all, my apologies for starting a new thread for a problem that it appears has been addressed several times with Fits going back to 2009. My reason for doing this is that having read all of those threads there seems to be no consensus as to the root cause of what appears to a widespread problem with Honda Fit a/c. Perhaps via this thread the fix will now present itself.

My story: I own a 2012 Fit Sport w/43K miles on it. Bought it brand new. Great car, yeah I know the mileage isn[t the greatest, but I love the car. No issues since I bought it except one: the a/c on long trips. I take one road trip a year, from LA to Las Vegas. The Fit has been on 5 of these trips. First two, no problem. Last 3, both going to Las Vegas and coming back, the same problem occurs about 60 - 90 minutes into the drive: the air gradually warms to the point it is no longer cool. Doesn't matter the traffic or outside air temp. I start out nice and cold and by the 60/90 minute mark I begin sweating and that continues for the rest of the trip. If I stop and have lunch, which I don't like to do, the car a/c is cold when I resume my trip but then it heats up again.

Numerous solutions have been listed on this forum:

• Cabin filter is dirty, needs replacing (I do this before every trip, it does nothing)
• Low refrigerant
• Defective evaporator thermistor
• Defective expansion valve
• Defective a/c relay in engine compartment
• Damaged condenser fins
• Defective compressor

My question is this: has anyone found the smoking gun that indicates which of these possible problems is the actual cause of the warm air on long trips air conditioning issue? It seems to me that given the commonality of the problem there should be one cause as opposed to so many possible causes.


Also, I have had my mechanic check the a/c on my Fit for the last two years after my road trips to Las Vegas and he said there are no leaks, it is full with freon and everything seems to be working properly. He asked me if the forums had any suggestions so that's why I'm here.


Sorry for the lengthy post but hopefully with some help we can put this issue with the Fit's a/c to final rest.


Bill

 

Mine blows warm all the time.

Always has.

Yet another reason I can't stand my car.

 

I know this isn't a solution, but a practical workaround I've found is to keep the temperature dial 2-4 clicks warmer than the coldest setting. Of course, YMMV. Hope it helps!

 

I run it at 3 instead of 4 (full blast).

Been like that since the car was new. Thankfully, I'm in a climate that's hot but not humid. I feel bad for the rest of you guys out east who have to put up with living in a swamp.

If it never cools down, then it's probably an A/C charge issue. The compressor won't run if the level of R-134a is too high or too low. It has to be exactly right. I paid a shop about $100 to do a level check / recharge when the car was 3.5 years old. It's been fine since, but I suspect it may need to be done again in the next year or two. Just consider it general maintenance that needs to be done, like tires or brakes.

 

Simple solution...take it to a different mechanic.

I don't know if it's true, but I have been told by a reputable source that all Honda's shipped out of Japan are slightly low on freon. This is to accommodate the multiple different elevations the car could be shipped to.

When our Fit was about a year old, my wife's dealership checked it out and found the refrigerant level to be slightly low. No leaks. Here we are 8 years later and it still blows ice cold after they added refrigerant.

I suspect that your mechanic isn't making sure it's at it's max freon capacity. He's probably checking it and it's within range vs being full.

 

You are icing up the evaporator.
So forget the following in your list :
Cabin air filter
Condenser fins
Expansion valve
Compressor

So what does that leave you?
Low refrigerant.
Evaporator sensor.
Compressor relay not turning off.

Low refrigerant should not cause a problem because the evaporator temperature sensor should turn off the compressor if it is running too cold. You could add a little refrigerant (a 5 minute job) to make the minimum temperature that the evaporator can operate at something above freezing. I usually shoot for 34 to 36 at the evaporator or 39 to 40 at the center A/C vent.

The Evaporator sensor should turn off the compressor at 40F +. It could be bad allowing the evaporator to run colder than freezing. I have not changed one a FIT but on some other vehicles you have to pull the whole dash apart to get to it.

There are some tricks that can be done to the external wiring by adding a resistor to fake out the computer when it sees the sensor. This is probably way above your mechanics skill level.

Compressor relays sticking seem common on Hondas. I do not know why. So if you want to shotgun this and replace the replay, have at it. It is simple to do.

If it were my vehicle, and not under warranty, I would add a little R-134 and watch the center vent temperature with a $10.00 meat thermometer from Walmart. Try to get it never to read under 40F in all driving conditions. If the evaporator can not evaporate below freezing then you do not need to worry about the sensor.

You are in a low humidity environment so it takes a while for the cold evaporator to accumulate enough moisture and freeze up using outside air. It will take even longer to freeze up using recirculated air.

If it does freeze up, keep driving and simply turn off the AC for a few minutes while leaving the fan on. The evaporator ice will melt while you are driving. You will actually feel the air getting colder as the ice melts and then get warm again after most of the ice has melted. At that point, or even sooner, turn on the AC again and continue on your way.

If your mechanic is using an AC machine, and not gauges, odds are he will not know how to add a little extra R-134. You can do it yourself with a can of R-134 from Walmart and a single gauge recharge hose, also from Walmart.

Or you can stop by here is NW Indiana anytime and I'll add a few ounces of refrigerant for free. I buy R-134 in 30 pound containers.

 

Sorry, there is no 'one size fits all' fix.
If the system has 100 different parts, there will be that many different possible things to fail, in twice as many different ways.

There are several things that are relatively common failures. Symptoms of each are vastly different if one knows what they are looking at/for, but to the appliance user the system simply doesn't work.

The casual observer/average driver only complains that "it quits working" and then whines about sweating and being uncomfortable, with little or no critical information about what the system was actually doing.

Much more information is needed before any sort of real internet guesswork can be done.



The guess about icing up the evaporator is a good one, BUT if this were the case the driver surely would have noticed a significant decrease in airflow from the dash vents as a small iceberg was clogging the ductwork, and the HVAC blower fan was still running on full blast.

If that wasn't noticed, then you'll probably have to drive it until it stops working, stop the car, open the hood, and observe whether or not the compressor clutch is engaged, and whether or not both radiator fans are running......Wait wait wait---FIRST you have to make sure you can tell if all of these are working or not so you know what you are looking at when the system stops cooling and you open the hood.

If your mechanic can't figure this out, he is broken and needs to be replaced with someone who actually knows about MVAC and can troubleshoot problems (a lost art IMO). The system will likely have to act up in order to be diagnosed, so someone may need to let it run for hours or take it on the highway to duplicate the problems, and he might need to take system low side and high side pressure readings while it acts up.

 

Slow airflow trough evaporator (due to restricted cabin filter or defective fan motor that spins slower than needed) will cause evaporator freezing and /or short cycling of the compressor with long pauses between cycles

 

Actually there is no difference between reduced air flow due to a partially clogged filter and turning the fan speed down. It should not freeze under either condition.

 

Found the right answer:
"The problem of car AC lines freezing up is caused by moisture that has been introduced into the system. ... Moisture in the system can freeze at that point, blocking refrigerant flow through the valve, and you'll notice you have warm air coming out of the vents."
The question is now how the moisture got introduced into the factory charged system?

 

We are not talking about refrigerant freezing. If there is moisture in the refrigerant system it would be captured by the dryer.

We are talking about moisture accumulating on the outside of evaporator. The moisture is condensed from the outside or recirculated the air passing through / over it. This condensation is normal and the condensed water normally runs off through a drain hose and on to the ground. If the evaporator surface is too cold then the moisture freezes and does not run off.

If the refrigerant system has not been opened and is still under some pressure, there is no way for moisture to get inside and mix with the refrigerant (r-134). When a system is opened up, we always replace the dryer and pull a vacuum to remove any air and moisture prior to recharging.

 

Agreed. The system is designed to cycle the compressor OFF when the evaporator core reaches about 37*F.

OP has not confirmed if the system cycles properly, or not.
OP has not confirmed if the compressor is, or is not, still engaged whenever the system quits cooling.

I also wonder if OP has a manifold gauge set?

You sure it's still got the original charge in itt? (FWIW it could have come from the factory like that, they are staffed with humans too)


A system discharged (or punctured as in crash damage) and left open to absorb moisture from the atmosphere coupled with insufficient deep vacuum level and time, saturated dessicant, poor work practices, and/or contaminated source refrigerant and/or equipment would be some likely causes IMO.

If one has an AC manifold gauge set connected to the system while the problem (moisture contamination causing internal freezing of the expansion valve) is actually acting up, one would be able to see a dramatic change in system operating pressures while it's happening.
Also, there would be no decrease in airflow through the dash vents if this happens, the only change noticed would be the temperature increase.

 

Thanks for all of these responses everyone. I am providing the thread to my mechanic and will let you know how it goes.

Bill

 

Make him do some diagnosis with gauges and a thermometer. Do not let him start throwing expensive parts at it.

Stick a thermometer int he vent and see what the temperature is coming out of the vent. It should never go below 40. Most vehicles run in the 42-44 range at the vent. It is slightly colder at the evaporator.

Run it until it fails and then check to see if the compressor is running and cycling. Park it (not running) and see if a lot water runs out of the bottom over the next hour at the ice melts off. Some water runoff is normal.

 

I opted to take the Fit to my dealer on Friday. Been going there for nearly thirty years and they are straight up.

Same result as with my mechanic. They could not get the system to fail. Ran the a/c for 2 hours with the car parked. Air was ice cold. My buddy the service manager had speculated that the problem could be electrical, whereby the a/c relay could overheat in driving. We opted to replace the relay since it was relatively inexpensive ($40.00). Now I need to do a road trip to see if the problem persists. If it does, next area according to him and the a/c tech would be the compressor clutch. If we go there I'll be going after Honda to kick in some $$ since it is obvious by the responses on this forum that the Fit does have an inherent problem with the a/c on long trips.

FYI the system checked out fine in terms of refrigerant level, leaks (none), etc. And I had just swapped out the cabin filter so that was not the problem.

Hope to hit the road within the next month and I'll post the results.

Bill

 

You did not mention the air temperature at the vents which is the primary question here.

Parking the car and running it at an idle is a poor test for two reasons.

1. At the an idle the AC compressor is running at less than 1/2 capacity.

2. Accumulated heat at the evaporator and engine will be much higher than running down the road. The system will never get down to the freeze up level.

Throwing a relay at it was a good guess. Let's see if it did any good.

If you haven't done it and Honda did not monitor it, go buy a meat thermometer from Walmart in the housewares section for $10.00 and install it in the center vent to monitor the air temperature to see if this is really a freeze up problem.

Good Luck

 

Totally agree. I knew the parking test wasn't going to yield any results.

I'll do the meat thermometer test when I take my road trip and will let you know. Thanks for the quick and informative reply.

Bill

 

Plan your road trip so you can have the system acting up AND arrive at the dealers service department while it's still acting up. DO NOT shut the car off, leave it running so they can verify you really have a problem and see why

Because if you shut the car off, the problem and all the evidence disappears.

 

 

I just completed a 230 mile round trip from my home in Los Angeles to Barstow, CA Began the trip at 9:40 AM, arrived back home 1:09 PM with a 13 minute break at a Home Depot in Barstow.

As I previously mentioned, I had my mechanic and my Honda dealership both check the car out. They could find nothing wrong with the a/c. I had the dealer replace the a/c relay with the hope it would solve the problem.

It didn't.

The test was conducted using a Weber digital meat thermometer inserted into the Fit's center vent. I was unable to get anyone to go with me so I had to log the times and cycle on/off temperatures myself which is why the times vary a bit. Still, you'll get the idea once you take a look at them.

Summarizing the results: the a/c works fine to starts, then gets colder, then ramps up the temperature until it stops working completely between roughly 64 and 66 degrees. Thanks for any advice/thoughts that you folks can offer.

My apologies for the formatting.
Here goes:
Time Cycle On Cycle Off Fan Setting 09:40:00 AM 83 - 4
09:45:00 AM 46.5 52.3 4
09:53:00 AM 43.8 51.1 4
09:59:00 AM 40.3 45 4
10:01:00 AM 39.3 46 4
10:04:00 AM 38.7 46.2 4
10:06:00 AM 37.6 44.8 4
10:09:00 AM 36.8 45.1 4
10:11:00 AM 38.3 44 4
10:14:00 AM 35.9 45.2 3
10:15:00 AM 34.4 44 3
10:20:00 AM 35.7 43.4 3
10:25:00 AM 36.8 44.7 3
10:30:00 AM 37.2 43.7 4
10:40:00 AM 23.9 36.6 4 Weird low readings, thought thermometer was malfunctioning. Went to into teens, then single digits, then settled in 20’s. Lasted a minute or two. 10:45:00 AM 25.8 35.8 4
10:47:00 AM 42.5 49.1 4
10:50:00 AM 40.5 44.7 4
10:52:00 AM 44.9 50.2 4
10:55:00 AM 45.4 51.2 4
10:59:00 AM 47.6 53.5 4
11:01:00 AM 49.4 54.6 4
11:03:00 AM 50 55.5 4
11:04:00 AM 51.1 56.3 4
11:06:00 AM 52.8 57.2 4
11:13:00 AM - 64.6 4 Exit Ave. L Barstow, 115 miles. Park at Home Depot. Compressor spinning but not cycling. Fans working. Turn off engine, go into Home Depot. 11:26:00 AM


Car “peeing” water like race horse. 11:29:00 AM 62.5 - 4 Started car, beginning temperature 11:32:00 AM 41.5 45.2 4
11:34:00 AM 41.3 46.9 4
11:37:00 AM 40.3 46.9 4
11:41:00 AM 39.2 44.9 4
11:44:00 AM 38.7 45 4
11:50:00 AM 39.5 45.9 4
11:55:00 AM 40.3 46 4
11:57:00 AM 40.6 47 4
12:00:00 PM 41.4 47.4 3
12:05:00 PM 40.1 47.1 3
12:12:00 PM 38.3 44.3 3
12:17:00 PM 38.2 45.3 3
12:22:00 PM 41.7 47.4 4
12:24:00 PM 43.3 49.1 4
12:27:00 PM 44.7 50.5 4
12:29:00 PM 45.1 50.8 4
12:32:00 PM 46.2 52.1 4
12:35:00 PM 46.9 52.4 4
12:38:00 PM 48 53 4
12:42:00 PM 48.9 53.9 4
12:44:00 PM 49.4 54.4 4
12:46:00 PM 49.7 54.8 4
12:49:00 PM 50.1 56 4
12:52:00 PM 51.5 57.4 4
12:56:00 PM 53.6 59.3 4
12:59:00 PM 57.4 59.5 4
01:01:00 PM 57.7 60.2 4
01:06:00 PM 55.3 61.2 4
01:08:00 PM 56.7 61.5 4
01:09:00 PM 58.6 63.3 4
01:10:00 PM - 66.8 4 Arrive home. Park. Compressor spinning but not cycling. Fans working. Observed water under car again.