heater won't always heat
 

I'm trying to troubleshoot a cabin heater issue on a base '07 Fit. The issue is sometimes the heater will not put out heat. It's been doing this for a few months now and I believe it was doing it a month or two last year at the end of Winter. The way to fix it is to turn the heat dial back from heat to cold and then back to heat a few times quickly. After a few turns, you literally hear a "whompf" noise from behind the dash and the heat kicks in. Once the heat is going, it is strong and doesn't quit the entire trip.

Has anyone fixed anything like this before?

Any ideas on what parts I should be focussing on?

thanks.

There's a cable that controls the heater door inside the heater box buried under the dash. Most likely the air mix control cable needs adjusting. You've got to swing the glove box down to get in there.

I know the cable you are talking about from when I replaced the radio. My recollection is that the cable is either attached or not, I didn't recall that there was a way to adjust it. But it doesn't matter, I should have access to the car (wifes') this afternoon so I will get in there and see what I can see.
thanks for the advice.

Maybe s sticky thermostat? I had a similar issue on my Integra back in the day. Weird how if you wiggle the knob back and forth it works though. Just my 2c.

Interesting fact is that the heater core on the Fit, as well as most cars today, is always circulating engine coolant. The temp knob controls a damper door that mixes the hot air w/ cooler air to provide heat to the cabin.

OP mentioned that when he does get heat it's hot and the car runs well so I wouldn't think it was thermostat related. And, having been in there for radio work the cable is most likely fudged up some how.

Good point, didn't think about that. My teg was super old.

Some have thought of by-passing the heater core. Thing is, if you do, you totally mess up the engine cooling loop. In the old days you could turn up the heater to gain extra engine cooling when crossing the desert. Today you crank up the AC... worry about yourself and hope you don't blow a head gasket.

After removing the glove box this afternoon, the fix was clearly evident. There is a metal bracket that holds the heater control cable insulation to the side of the dash. The screw was missing. So as the knob was turned most of the action on the cable was the slack being taken up rather than the actual cable itself moving the control piece. Found and inserted a screw and all is good again.
thanks all for your help.
https://lh6.googleusercontent.com/-Y...40/Fit_Fix.jpg

Lucky you found that screw, or at least one that worked ;-)

I SUGGEST EVERYONE FILE A RECALL.GOV COMPLAINT ON THIS SO THAT HONDA TAKES ACTION

My 2019 Fit with 82K miles also suddenly was without much heat. It turned out to be that the HVAC air temperature dial and cable are no longer able to operate the air box shutter / flapper through the full all cold to all hot air stroke length. Given the costly repair or large amount of time to replace the 79106-T5R-A01 air box (AC & Heater Case) and potentially the temperature controls (dash control unit 79560-T5R-A01ZA) for ~$400 and shipping - I've come up with a simple solution for the North - adjust the shutter/flapper fully forward toward engine for Winter (at/below 5 °C) and adjust the flapper all the way back (full cold) in late Spring. It's hard to stomach spending $2400 on an LX I bought for $17000 out the door (plain LX no options). I might put in a coat hanger-style push pull or 10-speed cable style control in that I can hide for more adjustment without removing the glove box.

In the attached picture the blue cable adjusts the air box flapper. That flapper has to be manually pushed forward toward the engine for full heat. The controls picture shows that your vertical rotation of the temperature dial results in a horizontal rotation of the cable in the cable reel.
https://cimg9.ibsrv.net/gimg/www.fit...57fe4e968f.png

https://cimg5.ibsrv.net/gimg/www.fit...07bd75df64.png


Now that I've opened the heat fully - I've never had such great heat so soon. I believe that my car always had an issue with the flapper not being able to move to full heat: (1) the knob was always very hard to turn past 1/2 cold since I bought the car new and (2) on full heat the car would take 10 miles to start getting nice hot heat driving at 60 mph on the highway (outdoor temps < 7 °C). Now hot air is available within a 1-2 mile drive.

It also appears that the GK Fit / Jazz / City (2015-2020) worldwide has this problem judging on WWW searches.