I just did an AC system overhaul on an '09 Fit. The compressor clutch had quit working, and, as it was an ill-fitting ebay replacement and the system had leaks, I bought a Four Seasons kit and did the compressor, drier filter, and expansion valve. That job went fine and the system now seals, but the compressor wouldn't kick on during recharging, even at ~85psi in the low pressure side of the system. I had figured it was either a relay, or that the cheapo clutch crapped out. This was not the case, but I did find a discontinuity between the clutch relay, which functions, and the connector going to the compressor. I have yet to trace the fault down, but I am fairly confident that this was the original issue.

HOWEVER, in the process of troubleshooting this, the AC system as a whole has ceased to function. Meaning, the idle no longer changes, the rad fans do not come on, and the evaporator fan does not come on when the AC button is pushed. Originally, all of those components kicked on, but with no action from the clutch. Now, there is no response whatsoever from the AC button being pushed. There are no codes on the dash, the #43, #47, and #10 fuses all show continuity, and the relays are all functional. Jumping the pressure switch doesn't do anything either.

My question is, is there a way to figure out if this thing decided to throw a DTC and disable the AC system while I was messing around? I linked to a service manual that describes an "MPCS short connector" that can be jumped in order to show codes from the computer that controls the AC system, but I can't 100% match that diagram to my fuse panel. There is a 2-pin connector on the bottom-right of the panel but I don't necessarily want to go jumping wires without a good idea of what they are. I figure it is a code because I was messing with the pressure switch and the wiring going to the compressor when it all quit out. I imagine it didn't like losing signal to one component or the other.

Thanks for any input. I usually work on old American junk; this was a favor and I am not in familiar territory.

https://hondafitjazz.com/manual3/en/...1938.html#i000

 

Start simple, did you bork your AC control relay? Might've killed it in your install. I lost one about 6 years ago, and whenever the AC button was on nothing would happen, no idle advance or nothing. Inspect/replace that first, it's behind the driver headlight in a little sealed plastic case with two other relays.

 

Thanks, yeah the relays are OK. I did a continuity test on all of them, and there is voltage going to the normally open terminals in the panel. For some reason the car is not sending voltage across the normally closed terminals in order to actually turn anything on.

 

I'd be leaning towards something going on with the transducer wiring, but you'd know better than me.

 

The compressor issue was indeed a fault in the wiring from the relay to the clutch, as highlighted below. There was rodent damage to all three wires that was concealed by the conduit and in a pretty hard to reach place. The inexplicable nonfunctional AC issue seems to have been based on the computer deciding that the AC compressor was giving an unsatisfactory signal, probably due to me jostling those wires, and disabling the system. I fixed the wires and reconnected the battery and it began working again. Even on a Honda, I figured 2009 would be old enough to avoid the nightmare that comes with diagnosing a modern car, but the Honda Diagnostic Obfuscation System strikes again. Now I have another anecdote for when people ask me why I drive a 22yo Grand Marquis.

Also, is there anything to be done about the rev hang? I took it for a test drive and it feels like I have to wait a full second after letting off the gas for the throttle to close, then clutch in. Otherwise the RPM jumps another 1-2k while shifting. I know it's an emissions thing, but it ain't great for the transmission to constantly be taking shifts under power.

 

Working on a 2013 Honda fit that has no power to the ac compressor . Initially fuses were blown and I replaced them . Relay is getting power. Relay tested good . Tried to use a scan tool to command the ac compressor on and compress clicks (key on engine off) also tried jumping the pressure switch but no luck. Replaced the ac button as well. Tested the thermal sensor has continuity. Any help is greatly appreciated.

 

Check if you get continuity from the #2 (2nd from top - towards rear of car) terminal of the AC compressor clutch relay (without relay installed) to the middle white wire in the ac compressor clutch connector. If there's no continuity you have a fault in the wiring between those two points. On my car, in addition to the rodent damage I found that the wire loom was dry rotted and cracking apart about 6" upstream from the compressor clutch connector. I'd check for wire failure around there.

You need to know whether it's just the clutch, or if the evaporator and rad fans aren't coming on either. That speaks to a larger issue in the HVAC and diagnosis will have to be done accordingly.

This website has good diagnostic aids:
https://charm.li/Honda/2009/Fit%20L4...th%20A%2FC%29/

 

Radiator fan is coming on as needed however condenser fan is not .

 

Hey @Benzler , the rev hang is present for two reasons: #1, a reservoir in the clutch master cylinder. If you want to resolve it, swap for an 01-05 civic CMC off ebay (mmmaybe check the "Clutch Delay Valve Delete" thread.. its been a few years for me)
#2 fuckin flywheel seems a bit heavy.. But I'm to understand that if you shave too much weight off it you throw a code. I went with a LUK flywheel and lost almost a pound without getting a CEL. Think it was like 12# vs. 11, or 11 vs. 10. Not much of a fix there, but the CMC swap is the real deal. Scroll through the thread, if you will, til you get toward the end. The original suggestion wasn't a direct swap, but in one post there was a recommendation for a CMC that is actually direct -- no pipe bending. I think it's the 01-05 civic.
Headrests from the coupe variant of that generation are pretty sweet, too. They don't jut forward so dang much.

I get that a jutting headrest is a safety feature.. but chronic neck pain is an injury all its own.

Edit: you can also remove and solder closed the orifice going to the delay valve in the stock CMC, but I didn't go that route due to uncertainty about solder and brake fluid.. Who would I even ask about that? Well, some guys went the solder route. I just did the swap

 

The 2G Fit A/C system is actually pretty dumb by modern standards. It has two differences compared to late 80's Honda systems (when fuel-injection and computer control became a thing): An evaporator temperature sensor instead of a thermostat switch, and the radiator/condenser fans are controlled by the ECM (a late-90's thing). The way the system is wired, the ECM simply can't tell the difference between a system fault and the driver turning off the A/C switch. The A/C demand signal (a electrical connection to ground) goes through a series of switches that all have to be contacts-closed (except the A/C button and windshield positions on the mode switch - that's an either/or) to activate the A/C system. Two of those switches are system-protection devices - the pressure switch and the compressor's thermal protector. Since the thermal protector wiring was broken, the signal from the HVAC panel simply never got through.