So its been a long while since I posted in here.

But here goes. So I have a K swap in my 98 Honda civic sedan with Kpro V4. I recently installed the Hybrid Racing K swap AC kit because I will be driving it from Texas to Georgia, and I’m not trying to dehydrate on the way.

So I installed everything, and tested all the connections and wiring. When I turn on the AC from the climate control the condenser fan comes on. With that done I went it got it properly serviced today. It holds the charge and there are no leaks. With all that done I started up the car and turned on the AC and I got nothing but hot air and the AC compressor won’t turn on. Knowing what I know about the Civic AC system I did all the checks. Checked fuse 17 under the dash, the relay in the engine bay, jumped power to the clutch and relay sockets and it turns on or clicks like it’s supposed to.

Went through my Civic and RSX shop manuals and did all the step by step checks as well, and still not getting the compressor to engage unless power is directly applied to the compressor. I have no idea what the issue is and it seems that I am the only person who has had this issue.

Does anyone have any idea what this might be? I haven’t heard of any issues with Kpro affecting this, but I don’t know it all. I don’t think it’s the AC pressure switch because I get proper voltage and continuity through it.

Any help or suggestions would be appreciated. Thanks.

Smitty

 

In the stock system, the ECU is part of the control of the compressor. When the button is pressed, the low power control wire from the cabin is grounded, which engages the condenser fan relay, starting the fan. This ground then passes through the pressure switch to the ECU. If the pressure is too high or too low, the switch will be open, which prevents the ECU from seeing the compressor start signal. If the ECU agrees that it is OK to start the compressor, the ECU will pull the compressor relay coil wire to ground. Involving the ECU is mostly so it can pre-emtively bump up the idle air into the engine before starting the compressor. The ECU will also cut out the compressor if the idle speed drops well below normal, in an attempt to prevent stalling out.

So one check you could make is that both wires of the pressure switch should go to ground when the button is pressed. Then you would need to investigate what happens with the swapped ECU, is it still in the loop or is the compressor relay now wired directly to the pressure switch?

 

I'll give that a try tomorrow. I did try my other 2 ECUs (one is a modified Doctronic ecu and the other is a JDM K20R ecu) and the compressor still doesn't kick on. i put a jumper wire between the terminal sockets for the plug for the pressure switch, but nothing happened.

 

i've been talking with David from HR about this matter and it seems i'm the first person to have this serious of an issue with this. been going through old forum posts, the service manuals, theories, and all that. still no dice. this is frustrating because i am always helping to fix my friends and families problems with their cars, and now i cant figure this out.

i'm going to look around some more before i tear out my dash and get new harnesses.

 

Hi Mate,
Did you finally find the problem? i have the exactly same issue with mi k-swap. I check all and I cant see the problem. The only difference, I running with ProEcu from doctronic, not Hondata.

 

Check if the fire wall heater core bypass is not stuck open, I know in the integra models they can get stuck and you need to manually move the lever in the engine bay to close or open it, there is a cable attached that goes into the cabin behind the climate controls.

 

Hi Wun, I can assure you that works.The problem is that the compressor does not start, just the fan.

 

Did you connect the A/C relay from the Hybrid-Racing kit correctly ?

 

Hi, I think yes.. But sure the problem is there. my Civic is OBD2A and the HR manual only see the connection for OBD1, I must have made some mistake in the wiring, To this day I still haven't found the problem. If anyone has installed this on an OBD2A and can share some information, I would appreciate it.

tnks!

Edit:
I resolve it, with the help of Doctronic support .My Civic es OBD2A arness with OBD2B wire.. (rare..yes, Civic fastback Euro version). The solution has been to connect the OEM ACC to pin E18 and the OEM ACS to pin E28 of my PRA (ECU EP3 euro version), with Multiplexer disabled (like Hondata), With this configuration the ECU controls the AC and does even do the idle up (you can set the idle RPM with AC on) and you even can configure a automatic AC off at a certain TPS or RPM value, all with Proecu-K..,
Regards!