Hello all,
Just picked up a 2009 Honda Fit base with 145k miles on it. Car runs great and has no issues besides the AC issue.

Previous owner has replaced the compressor, had the system recharged, the AC button replaced, and the relay for the AC clutch replaced. Dealer said this didn't fix any of the issues, and the tech claims the whole fuse box has to be replaced because that is where the issue lies.

I checked fuses 10 and 43 and they both were not blown, but I replaced them anyway to see if there was a difference. No luck there so now I'm attempting to diagnose if the issue lies with the fuse box itself. Are there any other fuses or relays to check on the 2009 Fit for this issue? Another thing I noticed is when the AC button is pressed, neither the radiator fan or condenser fan come on, so I was thinking maybe this could be related to the issue.

Thanks!

 

The AC button does't control the evaporator fan (blower motor). This is controlled by the blower speed knob. The radiator fan is temperature controlled by the temperature of the engine.

The fuse box should not be logically difficult to check but to check it thoroughly may be difficult due to access problem. I haven't checked but I'll bet its tight under the dash! Check your repair manual and online for instructions.

Clay Colvin

 

I read somewhere online that both of the fans on the radiator should kick on when the AC is on. The blower works fine as it should just blows hot air.

I checked the fuses in the box and the ones related to the compressor are fine. The dealer was saying to replace the whole fuse box, but that doesn't seem right to me. The compressor clutch doesn't seem to be engaging therefore no cold air.

I was thinking maybe the AC Pressure switch?

 

Yours don't run, so that's a clue.





How much pressure is in the system?

 

Yea I've had them both kick on at idle and turn off every so often. Car doesntd overheat or anything though. When the compressor was put in the system was recharged.

 

The radiator fans have to run when the coolant temp is high. That wasn't what I'm looking for.





How much pressure is in the AC system?

 

Is your AC button actually working? You need a test meter to check for voltage and continuity of wires and connections in the box. By the sound of it maybe a wiring problem from the AC button to the AC relay. This could be the wires or the box and its connectors.

As the other commenters have mentioned, have you checked the freon level? If the system leaks after being repaired you may not have freon charge.

 

My ac wasn't working recently on my 09 fit it many not be your problem if your compressor is in fact new, but my clutch was sticking in the released position when the ac was turned on. I sprayed it with some Krown t40 and worked it back and forth to free it up it hasn't skipped a beat since.

 

When I jump the compressor with power from the battery to get it going and measure the pressure, there is about 55 psi in the system.

Compressor does work when jumped directly or if I jump it at the relay box. Could the ECM/PCM be the issue?

 

If the psi is 55 on the low side at about 1500 rpm with the AC on high blower speed then your AC is overcharged. This can keep the AC from working properly. The correct psi is determined by the ambient temperature. You can find a scale online. Usually about 35 psi. If it comes on when you bypass the relay, is it cooling well? If so your freon is not the biggest problem but it should be checked.

Your circuit from the "on" button to the relay may be the problem. Have a test meter?

 

Okay, I do have a multimeter, what values should I be looking for at the on button in the car? Definitely worth a check, but not thinking it's the issue due to the fact that the dealer replaced it. Even if the incorrect PSI was in the system, when I jump the AC pressure switch shouldn't the compressor kick on? The compressor would only kick on when jumped at the relay, or directly at the compressor.

 

Yes, If you bypass the "on" button on the dash and the compressor comes on, then the "on" switch is not working. You can test the switch too. Turn it on and check for continuity. If it's good, check wiring and fuse box for current.

 

I wouldn't condemn that without serious testing. That's an expensive mistake to make.


Check if the thermal protector has gone open circuit. Check if the high pressure switch contacts are open circuit. Either of these failures would disable the AC system.

After this point I would have my scanner plugged in, after checking fault codes and whatnot, I'd definitely want to view live operating data to see

What it thinks the ECT is

if the PCM is receiving the AC ON request from the HVAC unit
(request path is HVAC > pressure switch > thermal protector > MICU, then MICU > FCAN network > PCM, then PCM > compressor clutch and fan relays)

If the PCM is attempting to operate the compressor clutch and fan relays, or if it might be inhibiting the operation of the AC for some reason...

then electrical testing however I decide is appropriate based entirely on my findings in the live data

 

Okay. I'll look into that. Would a compressor with a bad thermal progector still run when jumped ?

 

Yes, because the thermal protector on that car is not wired in series with the clutch. (compressor has a 3 wire connector)


The thermal protector is wired to interrupt the AC request circuit.



You need a wiring diagram!

 

this help?

 

OP may also want the page that shows the HVAC controls and the pressure switch

 

OP if you need more send me your Email Addy and I will send complete PDF file

 

Your welcome

 

Thanks for all the help everyone! Ended up following the wiring diagrams and repair manual from Black3sr and the thermal protector was bad. Given the age of the compressor I just replaced the whole thing and recharged the system to spec. All works great now !