Does the A/C compressor switch off in VTEC or at full throttle?
- Thread starter goldNSX
- Start date
Are you sure? The compressor run signal does go through the ECU and I would expect it would shut it off under some conditions.
off the cuff i agree with brian, most manu. cut comp. based on tps signal,looking thru ser man. i can see they are looking at but at this point i dont know if they shut it off ,will run car with scanner hooked up and see what happens ,very interesting!!!, we never stop learing
on some cars it does. don't have a definitive answer for you on the NSx
just hit the off switch before you WOT or turn the temp control from cool to hot.
usually have my heater turned all the way up hot and fan blowing for extended performance driving to help with additional cooling.
just hit the off switch before you WOT or turn the temp control from cool to hot.
usually have my heater turned all the way up hot and fan blowing for extended performance driving to help with additional cooling.
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The Climate Control Unit (CCU) commands the compressor clutch, looking at the logic on page 22-8 & 22-10 of the service manual. The CCU connection to the ECU is an output, telling the ECU to run a higher idle RPM to compensate for the extra load. However on page 11-25 item 4, the ECU can delay the engagement of the compressor clutch relay. If the ECU can delay the relay, it can also switch it off, if it wanted to do so, but I could find anything about this in the manual.
Maybe the triple switch as a say in this, but wouldn't the compressor clutch wear out much quicker engaging each time you fall out of VTEC range (still spinning at 6000 RPM)?
Roger
Maybe the triple switch as a say in this, but wouldn't the compressor clutch wear out much quicker engaging each time you fall out of VTEC range (still spinning at 6000 RPM)?
Roger
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- Joined
- 15 May 2004
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- 6,898
The A/C guy told me that it's very hard for the A/C system if it's turned ON at 7k rpm or so. Not for the clutch only but for the system pressure mainly. By turning ON I mean that A/C is switch ON by me and the system decides if it needs to have the compressor ON to keep the desired temperature.
Turning OFF the A/C in spirited driving conditions in the hot summer is NO option for me. I NEED it (both).
My 18-year-old R12-system is near to black death anyway as the compressor ran under conditions where there was zero, nada, nothing freon in the system what we've found out yesterday. Normally a pressure switch doesn't allow the compressor to run under low freon conditions but not this year.
Maybe next winter I'll renew the complete system anyway but first I want this problems analysed and elimianted. Thanks for the links to the SM, I'll have a diagnosis myself. Thanks for the heads-up!
Turning OFF the A/C in spirited driving conditions in the hot summer is NO option for me. I NEED it (both).
My 18-year-old R12-system is near to black death anyway as the compressor ran under conditions where there was zero, nada, nothing freon in the system what we've found out yesterday. Normally a pressure switch doesn't allow the compressor to run under low freon conditions but not this year.
Maybe next winter I'll renew the complete system anyway but first I want this problems analysed and elimianted. Thanks for the links to the SM, I'll have a diagnosis myself. Thanks for the heads-up!
Hi Gold,
The AC should shut off at a certain rpm, all automotive systems that I know do so and an NSX expert here in the Netherlands told me it does so on the NSX too.
I would asap have the AC checked by a AC specialist (these should know a lot more about it than a regular Honda dealer).
When it turned out that the AC pump on my NSX was locked up when I bought it, I got a fully remanufactured one for 280 Euro or so, with old broken one returned as core, so not too expensive.
I would do this before the whole system is compromised, as other parts will cost rediculous amounts of money to replace and a LOT of work to get them out of the dash.
Just my 2c
The AC should shut off at a certain rpm, all automotive systems that I know do so and an NSX expert here in the Netherlands told me it does so on the NSX too.
I would asap have the AC checked by a AC specialist (these should know a lot more about it than a regular Honda dealer).
When it turned out that the AC pump on my NSX was locked up when I bought it, I got a fully remanufactured one for 280 Euro or so, with old broken one returned as core, so not too expensive.
I would do this before the whole system is compromised, as other parts will cost rediculous amounts of money to replace and a LOT of work to get them out of the dash.
Just my 2c
- Joined
- 15 May 2004
- Messages
- 6,898
rseco6, thanks for your input!
Well, I'm not worried about my old compressor failing due to the high-rpm issue because it has been like this for 5 years or so.
Even in the case of a complete black death of the system I don't mind throwing $2000 at the car, taking out the dashboard and going the tabula rasa-way. The last 3 three years of the 18 years old system have been gift anyway. :wink: Until a few years ago the A/C was just a $5000 (in Europe) bill to me. :wink:
What I try to do is to understand (as a greenhorn in A/C) how the A/C in the NSX works and where the problem lies. We've some professionals for every kind of work here maybe for A/C also. I HAVE to diagnose the problem this way because no garage will ever touch my car again.
I had a closer look in the SM and there is a middle pressure switch which lets the ECU know to raise idle as soon as the A/C clutch grabs. There is also a tripple (!) high pressure switch which should shot the compressor off in low freon conditions and also shots it off under too high pressure conditions. For the later one: under what circumstances could this be the case? High rpm? Is it regulated this way? The high pressure switch shots the comp. off while exceeding xxxx rpm? At which rpm should the comp. be shot off? Do you have examples?
My A/C board has been revised a few years ago and works fine. I point my finger on the high pressure switch for having a compressor running with no freon in it. Right?
Interesting. As you say the SM don't tell us all of how it works together. One point: If the ECU can retard the clutch operation does that also mean that it really cuts the comp. under full load?
As for the clutch it's magnetic.
Can anybody tell us more about how the A/C and ECU work together.
Well, I'm not worried about my old compressor failing due to the high-rpm issue because it has been like this for 5 years or so.
Even in the case of a complete black death of the system I don't mind throwing $2000 at the car, taking out the dashboard and going the tabula rasa-way. The last 3 three years of the 18 years old system have been gift anyway. :wink: Until a few years ago the A/C was just a $5000 (in Europe) bill to me. :wink: What I try to do is to understand (as a greenhorn in A/C) how the A/C in the NSX works and where the problem lies. We've some professionals for every kind of work here maybe for A/C also. I HAVE to diagnose the problem this way because no garage will ever touch my car again.
I had a closer look in the SM and there is a middle pressure switch which lets the ECU know to raise idle as soon as the A/C clutch grabs. There is also a tripple (!) high pressure switch which should shot the compressor off in low freon conditions and also shots it off under too high pressure conditions. For the later one: under what circumstances could this be the case? High rpm? Is it regulated this way? The high pressure switch shots the comp. off while exceeding xxxx rpm? At which rpm should the comp. be shot off? Do you have examples?
My A/C board has been revised a few years ago and works fine. I point my finger on the high pressure switch for having a compressor running with no freon in it. Right?
Interesting. As you say the SM don't tell us all of how it works together. One point: If the ECU can retard the clutch operation does that also mean that it really cuts the comp. under full load?
As for the clutch it's magnetic.
Can anybody tell us more about how the A/C and ECU work together.
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