Driving a 2010 Honda Fit with 70k miles. Bought it certified pre-owned in 2014.

Took it to a mechanic last week and had a complete vacuum/recharge of the a/c unit with a dye test and no leaks were spotted. The problem was not solved.

We don't drive our fit much; maybe 2-3 times a week. Our a/c doesn't seem to be working normally, but I can't tell how much of this is due to the fit's a/c unit being notoriously underwhelming, or an actual fixable not-outrageously-expensive problem. The problem in a nutshell:

- a/c unit will SOMETIMES start blowing regular outside temperature air cyclically. Sometimes once every 10 minutes, sometimes once every three minutes.
- when it does this, the fan speed DOES NOT decrease.
- the compressor DOES NOT stop running
- there is NO NOISE heard during the "switch"
- regular air will flow through the vents for 1-5 minutes, then the a/c will kick in again. Again, no noise, no vent speed/flow change ... just the air will feel cold again.
- no ice/frost/moisture comes from the vents when the switch happens either turning a/c on or off
- recirculating air or outside air vent setting has no effect
- fan speed of 4 vs 3 vs 2 etc has no effect
- cruise control vs manual has no effect
- higher rpms has no effect, such as going uphill at 70 mph vs going downhill at 70 mph. If anything, we thought maybe the a/c worked better at a higher rpm.

The only thing that DOES seem to have an effect is the outside air temp/humidity level. For instance, we drove 400 miles on friday - temp was 70, low-ish humidty, a/c ran GREAT the whole time and never "switched". On the ride home yesterday, temp was upper 80s, HIGH humidity, and the a/c switched on/off continuously the entire ride, with it switching every 15 minutes at the start of the drive and increasing up to switching every 3 minutes towards the end of the drive. Then this morning I commuted to work, 25 minute drive, outside temp of 70 with low-ish humidity and a/c ran fine the whole time.

When the mechanic did the vacuum/recharge and told me my car was fine, he had tested it on a low humidity day.

So: what's the problem? I don't think it's overcharged, or the temp sensor (because it's not freezing the line, I don't think). The fact that the air blows the same whether it's switched on or off makes me think it's not plugged, because then the air speed would lessen, yes?

TL;DR why is my a/c running well at low humidity and sucks eggs at high humidity? that's the only time I really want my a/c to work.

 

Hopefully the system was charged properly. Charging by weight is the most accurate method. If it was under or over charged issues will occur. If the suction line (larger line) that exits the firewall is icing over that's a sign of low refrigerant charge. Yes, high humidity and temps affect the amount of cooling but if the system is functioning properly you should not be having these issues. Check the condition of your cabin filter and look at your condenser for blockage and bugs.

 

What bothers me is your statement that the compressor does not shut off. When we hear of high humidity failures, low R-134 refrigerant charge levels and evaporator freeze up is highly suspect. That does not fit in this situation because you say it clears up on it's own. Freeze up usually requires shutting down the AC for 5 to 10 minutes to melt the ice.

So I suspect a slightly over charge situation. If it is over charged the problem will show up and get worse as the outside temperature rises.

You need to verify that the compressor is actually running when the failure occurs.

 

I have been having the same issue with mine. It used to stop blowing cold air on long trips (low humidity). Lately it has been so humid that it hardly works at all. Went into store came out 1 hour later still didn't work. Next day, not so humid worked great.

Ill post what I find out.