A/C pressure switch
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Re: A/C pressure switch
It is supposed to cut off if pressure is < 50 psi or > 450 psi. These pressures only happen when something is wrong. The switch will be closed at all times during normal operation.
Do not jump the switch unless you have gauges connected and are watching the high side pressure.
Do not jump the switch unless you have gauges connected and are watching the high side pressure.
Fish Twig
Joined: Nov 2005
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From: Still hunting that foo up there
Re: A/C pressure switch
It is supposed to cut off if pressure is < 50 psi or > 450 psi. These pressures only happen when something is wrong. The switch will be closed at all times during normal operation.
Do not jump the switch unless you have gauges connected and are watching the high side pressure.
Do not jump the switch unless you have gauges connected and are watching the high side pressure.
Thread Starter
Honda-Tech Member
Joined: Jan 2018
Posts: 1,903
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From: Mississippi
Re: A/C pressure switch
It is supposed to cut off if pressure is < 50 psi or > 450 psi. These pressures only happen when something is wrong. The switch will be closed at all times during normal operation.
Do not jump the switch unless you have gauges connected and are watching the high side pressure.
Do not jump the switch unless you have gauges connected and are watching the high side pressure.
I have A/C in my J-swapped Civic, and I think this means I need to add a low side cycling switch. Since I have no other modules to govern when the ECU turns on the condenser fan and clutch coil relays, I had to wire them both up through the a/c thermostat to be grounded by the a/c switch.
The Accord ECU has switched grounds for these circuits and switches them on via signal from the BCM (which is not present on the Civic) through CAN wiring.
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Re: A/C pressure switch
If it's still a TXV system it should be set up to cycle on evaporator temperature. Pressure cycling is for orifice tube systems. That pressure switch is on the low side.
The only modification really needed is what you've done: connect the compressor and fan relay coils directly in parallel instead of having the compressor loop through the ECU, BCM etc. The loop through the ECU is not for pressure or temperature control. It is so the ECU can pre-emptively increase the idle air before the compressor engages.
The only modification really needed is what you've done: connect the compressor and fan relay coils directly in parallel instead of having the compressor loop through the ECU, BCM etc. The loop through the ECU is not for pressure or temperature control. It is so the ECU can pre-emptively increase the idle air before the compressor engages.
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Thread Starter
Honda-Tech Member
Joined: Jan 2018
Posts: 1,903
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From: Mississippi
Re: A/C pressure switch
If it's still a TXV system it should be set up to cycle on evaporator temperature. Pressure cycling is for orifice tube systems. That pressure switch is on the low side.
The only modification really needed is what you've done: connect the compressor and fan relay coils directly in parallel instead of having the compressor loop through the ECU, BCM etc. The loop through the ECU is not for pressure or temperature control. It is so the ECU can pre-emptively increase the idle air before the compressor engages.
The only modification really needed is what you've done: connect the compressor and fan relay coils directly in parallel instead of having the compressor loop through the ECU, BCM etc. The loop through the ECU is not for pressure or temperature control. It is so the ECU can pre-emptively increase the idle air before the compressor engages.
Fish Twig
Joined: Nov 2005
Posts: 15,554
Likes: 309
From: Still hunting that foo up there
Re: A/C pressure switch
I would just wait until you get the full size condensor before doing any more testing. I looked up condensers for an 05 honda accord v6, since you didn't specify a yr I'm guessing it was that generation (not in your build thread either), and the condenser in that model is 25 3/4 x 14 15/16 x 5/8. You sir are undersized by using a 12 x 24
Thread Starter
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From: Mississippi
Re: A/C pressure switch
I would just wait until you get the full size condensor before doing any more testing. I looked up condensers for an 05 honda accord v6, since you didn't specify a yr I'm guessing it was that generation (not in your build thread either), and the condenser in that model is 25 3/4 x 14 15/16 x 5/8. You sir are undersized by using a 12 x 24
2003 Accord EX coupe is what the swap is from. Don’t know why dummy didn’t put it in the build thread.
12x24 as big as I think I can fit properly without cutting the bumper cover to shreds. It’s better than the 12x14 I have now.
Fish Twig
Joined: Nov 2005
Posts: 15,554
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From: Still hunting that foo up there
Re: A/C pressure switch
You’re right on the testing. That’s the advice I usually give customers! Wish I’d listen to it.
2003 Accord EX coupe is what the swap is from. Don’t know why dummy didn’t put it in the build thread.
12x24 as big as I think I can fit properly without cutting the bumper cover to shreds. It’s better than the 12x14 I have now.
edit: would the integra condenser work?
Thread Starter
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From: Mississippi
Re: A/C pressure switch
126 cu in (currently)
157 cu in Civic unit
211 cu in (12x24 unit ordered)
240 cu in Accord unit
250 cu in Integra unit
The Teg condenser has the highest volume, but I would need more specialty fittings and have the hoses remade. A unit 14 x 24 x 3/4 would be slightly greater than the Integra condenser by about 2 cu in. If I had the space, I’d use that.
157 cu in Civic unit
211 cu in (12x24 unit ordered)
240 cu in Accord unit
250 cu in Integra unit
The Teg condenser has the highest volume, but I would need more specialty fittings and have the hoses remade. A unit 14 x 24 x 3/4 would be slightly greater than the Integra condenser by about 2 cu in. If I had the space, I’d use that.
Fish Twig
Joined: Nov 2005
Posts: 15,554
Likes: 309
From: Still hunting that foo up there
Re: A/C pressure switch
Is the compressor same between K and J series? Never looked. Also the crv uses a full size condensor too, engine bay is similar to the civic. Have you looked into that?
Thread Starter
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Posts: 1,903
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From: Mississippi
Re: A/C pressure switch
CRV condenser is dimensionally the same as the Integra.
Their bays are quite similar, but that thing’s not fitting in the normal spot:
You can’t really see it too well, but that O2 sensor, exhaust pipe, and compressor really aren’t going to make good friends with a CRV or Integra condenser mounted on the backside of that radiator support.
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