First post on FF and recent new owner of a 2010 Fit Sport MT with 160k miles to be the better half of my '01 Miata. Car has been flawless for the few months I've had it, love the practicality and it's almost as fun to throw around as the Miata! Bought the car knowing that the A/C wasn't working but this was at the end of October and it was starting to get cold so I didn't worry about trying to fix/diagnose it right away.

Now that it's been a bit warmer I started looking into the A/C issue and have determined exactly what it's doing:
A/C always works from a cold start, nice and cool and not intermittent while idling, I've let the car sit idling for half an hour and still works as flawlessly as it did at minute one. If I start driving I can get a couple miles down the road, not more than 10 minutes, before the air starts getting humid and warm. If I drive back and let the car idle cold air will not return. I have to turn off the car completely and let the engine cool down for ~30 minutes before I can turn the car back on and have seemingly infinite supply of cold air only while idling, if I start driving, it's goodbye A/C.

​​​​​​Searching on the forum, seems like A/C issues are common but no one seems to have quite the same issue I'm having.​
Some things I've tried and/noticed are:

• Checked refrigerant line was pressurized
• Turning off A/C for ~30 minutes while driving, doesn't come back
• After driving with no A/C, letting the car idle with A/C off and heat cranked for ~30 minutes, doesn't come back
• Turning A/C on and off while it's working to check if the compressor is engaging, hear it click and works fine
• Turning the compressor by hand feels fine, nice and smooth with a little "fluid" resistance
• Replacing the A/C and the A/C Clutch fuses
• Swapped the A/C relay (the A/C relay in there was a very new looking Denso unit btw...)

My theory is something sensor related? I dont think it's anything burned up or mechanically damaged, and I doubt it's the pressure or refrigerant amount because again, it works flawlessly just idling when the car has had a chance to cool off, not intermittent at all, I've sat in it researching and writing this for the past 45 minutes and it's still working perfectly.
So I'm pretty stumped, and advice from some A/C gurus would be much appreciated. Ready to answer questions and troubleshoot anything specific. I want to make this the best daily on the planet!

 

Does the main engine electric cooling fan come on when the AC is engaged?
Any goofy stuff from the previous owner such as cardboard covering the radiator (for "cold weather") or excess dirt and debris built up on the condensor or radiator?
Do you get the compressor clutch "click" when you turn the AC switch on and off when it's not working well (ie. blowing hot after 30 minutes)?
Any change in how it works when it's "working" whether your interior fan speed is high or low? If when it stops working well you set the fan to the lowest speed, any difference?
Does it stay working well for longer if you set the cabin air to recirculate mode? (when AC is engaged it will work far less hard dehumidifying if you recirculate)
I would ask if you have inspected the bowden cable which operates the mix flaps and the coolant control valve for the heater core, but even if these were to blame the air should be warm and dry, not warm and humid if the AC is running.

It could be undercharged or overcharged (kicks out on high head pressure) or not shedding heat at the condenser due to fans inoperative or dirt clogging the passages.
Just some ideas.

 

Hey surly, thanks for the reply,

Both fans come on when the A/C button is turned on, they worked fine when I switched the fan relay to test the A/C relay too.
Condenser looks great besides a few bugs lodged in the fins. No serious dents or debris that would block anything, front or back.
Compressor doesn't click or kick on at all when the air is warm. Checked visually under the hood too and it doesn't engage when A/C button is on and air is warm (engages totally fine when idling from cold though...).
I've tried setting it to two clicks under max A/C and also tried lowering fan speed and both of those together. None of it has an effect.
Recirculate doesn't prolong A/C working while driving any noticeable amount.
I haven't inspected the cables but operating the knobs they feel fine, and like you said wouldn't indicate the issue I'm having if that was the issue.
If it was undercharged or overcharged it wouldn't operate so flawlessly idling from cold though right? I'm not privy to A/C on cars so I could be wrong, but evidence suggests otherwise? Some conjecture to this; I'm actually only the second owner and from my understanding the car was serviced at the dealer its entire life so I would assume that the A/C would have been charged correctly, and it's certainly been touched as the cap for one of the valves is missing (tbf, the capping missing could suggest it not being charged correctly, but i digress).

In other news, I got home from a 40 minute drive in 80 degree weather with A/C doing it's usual thing of not working, (not exactly pleasant, but bearable) and decided to try something. Once I parked and turned off the car I disconnected the battery and reconnected it theorizing a stuck sensor value or something similar could be the culprit... no dice.

Still digging, thank you to future readers!

 

Cars have design feature that shuts off the ac when accelerating on the road to reduce power loss to ac at that time. Get a good scanner attached to the car and monitor the ac when on the road for confirmation of this. What parts or wires to repair is unknown to me, but the problem will be confirmed. This is an interesting problem, I'll look into this and give you a better answer. Clay

 

While I'm not sure what could be causing this I am wondering about the A/C button. Could the button contacts/wires be loose and just turning it off when driving because of vibration?

 

Check the pressure switch on the condensor on the left side when facing the front of the car. It collects dirt because it's mounted with the connector facing upward. Clean the connection and use dielectric grease to seal around the connection afterward. It's a problem with these cars, but easy to fix in a few minutes with cotton swabs and alcohol and some dielectric grease. I'm not sure this will fix your problem, but it's the first thing I would check after having had a shutoff ac problem. Best of luck, Clay

 

i was going to mention this, but I had no useful info beyond it. The Fit was the first and so far only car I became aware of having this, because it hasn't got a ton of power and so this shutoff was a must. I don't know if other vehicles have a similar thing.