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Hi all,

I have an issue with the A/C system. The vehicle was sitting for a long time. The vehicle was used very minimally in the last 5-6 years. Before that, AC worked fine. I think the system might have gotten low on refrigerant during this time. I recharged the system using 2 refrigerant cans (12 oz.) I didn't fill in the second one entirely. I believe it might have been around 18 or 19 Oz. I was using the gauage as a reference. I had to hotwire the system for clutch to engage and filled the system that way.

The issue is that when I press AC button, nothing happens. The clutch won't engage unless it is hot wired. I believe the condenser fan does not turn on either when I turn the AC button on using internal controls. However, the system seems to work fine when I have it hot wired. It blows cold air. The pressure is also within green range. I have already swapped relays, so I am sure the relay is not an issue. If I keep it hot wired, can it create an issue?

Thanks!

2002 Honda Civic

 
Rep Power: 367

check if rodents got in and chewed wires

 
Rep Power: 224

That would imply the system was completely empty. Did you check the pressure before filling? If it was empty it should really be vacuumed first as well as the drier replaced.

You shouldn't have to jump the compressor to fill, if everything was working properly.

If you leave the compressor engaged the system can freeze.

Also, when you press the A/C button does the green indicator light come on? It should as well as both the rad and condensor fans.

 
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Okay, I will check the wires. I doubt wires might be chewed, but have no clue as there are no other electrical problems.

@BrotatoChip
I did not evacuate and create a vacuumed before filling it again. I have not replaced any hardware as I was just thinking it was due to low r134a.
I did not check the AC pressure before filling it. As I was re-filling I noticed it was very low and then slowly climbed up. It did go high once, but I let out some gas and it was fine.
I was looking up as a possible solution and there were suggestions that if refrigerant is low, you'd need to hot wire to get clutch to run and accept the gas.

When I press the A/C button, it does light green, but compressor does not kick on.
Can hot wiring in summer be fine as long as I am using the AC. I am guessing if I leave it hot wired and then not open vents, maybe it could create issue?

 
Rep Power: 224

You vacuum first to remove the air inside as well as the moisture. The moisture (if the system was empty) will cause problems in the future.

I can understand why someone would think that. The pressure in the R134a can is enough to trip the low pressure switch and engage the compressor though.

Check the low pressure switch. Located on top of the drier, going to be a pain to get to. It's mounted on the body basically right next to the compressor. As long as it sees above ~28 PSI it should be closed. Use a multimeter to check continuity across the two pins.

The compressor is cycled for a reason. Even in the summer it can freeze.

 
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Thanks for the info!!
I really hope it's the pressure switch. If not, I am not sure if I want replace parts in this car. haha
How hard is it to get to the pressure switch? Do I access it from underneath? I also have an issue with the hood latch. It doesn't work well. I might slam the hood 20 times and it will work once. I have broken the hood latch tab (the one you access from cabin).
If I get access to the pressure switch, hopefully, I can just hot wire it and see if the system functions. If it does, we know it was the pressure switch.
edit: Maybe hot wiring the pressure switch might now work if it doing so makes pcm recognize it as a very high or a very low pressure.

Thanks!

 
Rep Power: 224

I don't know what the easiest way to the pressure switch is. The engine is on the passenger side in my Civic so there's gobs of room over there for me to get to it. You may be able to remove the headlight for more access?

If the pressure switch is bad best thing to do would be replace it. If you jump it and the system goes low in the future you will destroy the compressor. Refrigerant has to be removed to replace the switch too, good time to fully evacuate the system and properly refill (after replacing the drier).

 
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So I believe I was able to access the drier. It is a cylinderical with a sensor on it. I disconnected the sensor, and turned the ac on, which didn't work. I also hot wired the connector (going to PCM) which didn't work either. At first, the engine would not turn over, but on the fourth crank it did, but still no AC.
I then hot wired the relay box and turned the ac on, cold air started blowing, but I noticed the condenser fan had not turned on.
Does this indicate anything?
Also, when the car idles and needs to cool down, both fans come on and turn off after a while.
Thanks!

 
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any thoughts? @BrotatoChip

 
Rep Power: 224

Looked at this thread while on my phone and forgot to reply when on my PC. Hoping you have some electrical troubleshooting knowledge because this is going to get messy.

So, you jumped the two terminals together at the low pressure switch and the compressor did not turn on when the A/C button was pressed? We can assume the relay is okay for now since you swapped it with no improvement. Next, let's verify the HVAC controller is actually pulling the output low when the button is pressed. Go back to the low pressure switch, with the A/C button on, one of the terminals in that two pin connector should have ground (my schematic is saying a solid blue wire). If so, next check continuity through the low pressure sensor just for good measure.

If those check out, next step would be verify the ECU is pulling a pin low to activate the relay, this would be pin E18 (red wire). Check from that pin at the ECU, if it is good find the correlating pin at the compressor relay and recheck.

 
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Yep, nothing happened when I jumped the terminal at AC pressure switch. I will try to see AC button is pulling the ground next.
btw, is the condenser fan supposed to turn on when you press the AC button? It wasn't turning on when I had hot wired at the relay.

Thanks!

 
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When everything is working properly, yes. When bypassing the compressor clutch relay, no.

 
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oh good to know! Part of me wants to leave it wired (I haven't done that for more than 10 mins), but then I read another post about ac compressor seizing up. lol
I will try to do a continuity check as you suggested.
I am not sure if I will be able to check pin E18 at the ECU, so I might leave it checking the harness for the ac pressure sensor.

Thanks!

 
Rep Power: 224

E18 at the ECU runs to the coil side of the compressor clutch relay, you could check it there as well. At the relay one of the coil side pins should have power anytime the ignition is on, the other should be pulled to ground if the ECU is trying to turn on the compressor. I would definitely start with checking the output from the HVAC control panel first (the blue wire at the low pressure switch). If I'm remembering correctly we have seen a few of those go bad.

Still wouldn't recommend leaving the relay bypassed all the time. If the system freezes you can damage the compressor.