Keeping the AC on an S14
~~Keeping the AC on an S14~~
Hey fellas we have been throwing this idea around at racebread.com but thought I'd see what you fellas had to add. I was going to attempt to keep my AC with my RB swap. And if possible use the R33 Climate Control unit instead of the stock S14's. how hard would it be to get the AC running correctly on the RB even if I can't use the Digital climate control off the R33? ANY info welcome (like both pinouts from both Climate control units, and anything else) Thanks for read hope you can help!
i was going to use the r33 climate control. then when i was pinning out the r33 climate control, i fried it
would be easy if you could get the pinout. i even saved the temp sensor off my clip. just get that and match wires id assume
also rumor is that a z32 harness had plugged into it and it worked. just a rumor though...
would be easy if you could get the pinout. i even saved the temp sensor off my clip. just get that and match wires id assume
also rumor is that a z32 harness had plugged into it and it worked. just a rumor though...
I had ac on my s14 with an rb20. the only problem was when you turn it on it was on all the time, the safety switch was not hooked up so I had to turn it off after a while to not freeze my lines. The problem was the rb20 ecu did not have the same ac control as the ka s14 ecu,so I had to wire the compresor directly, but if the r33 ecu has the same wires and can control it should work like factory.
Re: (dekand)
O.k so all i need to do is swap the plug on the climate control harness to use the R33 controls, and get a pressure switch to wire in on which wire? the one leading the the compressor? and just have the AC shop run the pressure lines from the R33 compressor (which i need a new one by the way) to the S14 condensor?
Re: (Wulfgang)
o.k we can def figure this out with all this brian power here. I looked at the pinout guides on both ECU and the s14 ECU seems to have a lot more wires related to the ECU. But my idea like i said is to convert the climate control unit's wire harness to the R33's Plus (wire for wire) and then I thought it would go to the correct Plug on the R33 ECU ?!? But if i were to do that and just run the wire directly to the pressure cute off switch would that work? or would it need to run from the control unit to the switch to the ecu?
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kouki-gymkhana
- Posts: 624
- Joined: Sat Aug 16, 2003 11:54 am
- Car: 1993 Nissan 240SX (only 90,000 mi!)
Re: (dekand)
Yes, that is the receiver/dryer. It should be about the size of a coke can on an s13. The pressure switch is located there as well.
Re: (kouki-gymkhana)
so why not just make sure the wire(s) coming from the R33 ECU goes to the dryer and pressure switch from the R33? wouldnt that rap it all up ? as long as you've wired the ECU correctly I mean. you could even use the R33 Dryer and pressure switch
Modified by 300Plus at 8:28 AM 7/12/2005
Modified by 300Plus at 8:28 AM 7/12/2005
Re: (300Plus)
would that work ^
should be a matter of just making sure the wires leave the ECU and go to the swtich and compressor ? right???Picture of RB25 ECU wait to load
should be a matter of just making sure the wires leave the ECU and go to the swtich and compressor ? right???Picture of RB25 ECU wait to load
That wiring diagram looks slightly suspect, but assuming it is correct, the explanation is simple:
The thermo control amp sends a signal to the ECU, pin 46, telling the ECU that the A/C clutch needs to turn on. The ECU then decides whether to pass the signal or block it. If the ECU passes the signal, it pulls pin 9 low (to ground), causing the compressor clutch to engage only if the triple pressure switch is also closed (which it will always be if your system is working properly).
So there are two wires needed to get it working, not one. The ECU needs to get the thermo control signal and the clutch relay needs to get the signal from the ECU.
If you also have an FICD (the RB20's do not), then it should also be wired in to the clutch relay output.
The thermo control amp sends a signal to the ECU, pin 46, telling the ECU that the A/C clutch needs to turn on. The ECU then decides whether to pass the signal or block it. If the ECU passes the signal, it pulls pin 9 low (to ground), causing the compressor clutch to engage only if the triple pressure switch is also closed (which it will always be if your system is working properly).
So there are two wires needed to get it working, not one. The ECU needs to get the thermo control signal and the clutch relay needs to get the signal from the ECU.
If you also have an FICD (the RB20's do not), then it should also be wired in to the clutch relay output.
Re: (Wulfgang)
http://racebread.com/smf/index.php?topic=114.0
confused please help lol When it comes to Wiring the AC I'm def a noob. I plan on swapping the R33 climate control over to my S14 wire for wire and and then running whatever wires needed to the compressor, pressure switch and all. an info on the subject no matter how small would be greatly apreciated. That picture came directly from the R33 FSM. I still need to find pin out guides for both Climate controls (R33 and S14) I mean if someone wants to dumb it down for me with a simple paint diagram lol I'll take anything. Thanks Fellas
confused please help lol When it comes to Wiring the AC I'm def a noob. I plan on swapping the R33 climate control over to my S14 wire for wire and and then running whatever wires needed to the compressor, pressure switch and all. an info on the subject no matter how small would be greatly apreciated. That picture came directly from the R33 FSM. I still need to find pin out guides for both Climate controls (R33 and S14) I mean if someone wants to dumb it down for me with a simple paint diagram lol I'll take anything. Thanks Fellas
Re: (300Plus)
I think if you want the R33 climate control, then you are on your own. I consider it a waste of effort, especially on a car as small as a 240, but I will not get into that.
But first you need to understand how the basic A/C system works on Nissans. Inevitably, problems will arise, and you will be much better off when troubleshooting if you know how things are supposed to work.
I assume most people know about the evaporator, condenser, and dryer. So first off, a list of the major control parts and their functions:
1. A/C clutch. This just engages the drive belt on the compressor. It is actuated by a relay. When the clutch comes on, the A/C gets cold.
2. Triple (or dual) pressure switch. This switch has an overpressure switch, an underpressure switch, and in some cases (triple) another switch that can be used for fan control. This switch is normally closed. The dual pressure part is the important part. If your system pressure gets too high for whatever reason, the overpressure switch will open to protect from explosion or compressor failure. If your system pressure gets too low, usually from leaking refrigerant, the low pressure switch will open to protect the compressor. The dual pressure switch is usually wired directly in series to the A/C clutch relay. This means that no matter how the climate control is working, no matter what the ECU does, no matter what else is going on, if the pressure is too high or too low, the A/C WILL NOT COME ON. Now that you know about the triple pressure switch, forget about it. It is there only for safety, not for control. It DOES NOT cycle the compressor. Unless your system is broken, the triple pressure switch will always be closed.
3. Thermo control amp. This is basically a temperature controlled switch, much like the ones you use to control your radiator fans, but somewhat more sophistocated. This is what "cycles" your compressor on all systems (fully automatic climate control or manual on all S13/S14 and all R32/R33 -- I don't know about R34). The thermo control amp is necessary because in most cases, the compressor does not have a capacity control. It pumps refrigerant based on how fast it is spinning. For example, if you are driving along the interstate at 3000 rpm, then the compressor is pumping a huge amount of refrigerant. With this much refrigerant, it is easy for the evaporator to get too cold and ice up. So the thermo control amp senses the evaporator temperature and sends out a signal when the temperature gets too low. Likewise, when the evaporator gets warm again, the thermo control amp sends out a signal that it is ok for the compressor to switch back on. This is the "cycling" you have heard about. Some cars use a separate low pressure switch to achieve the same thing.
So the basic control scheme is this: You push your A/C button on your dash. The button powers up the thermo control amp. The thermo control amp switches on the A/C clutch and the compressor comes on. You feel cold air. Then, when the evaporator gets too cold, the thermo control amp switches off the A/C clutch. You may feel the air begin to warm up just a tad. Then the thermo control amp switches back on the compressor and the cycle repeats. If the refrigerant pressure gets really, really high or really, really low, then the dual pressure switch opens shutting off the compressor to protect it. Since the thermo control amp knows nothing about the pressure, it might still be trying to cycle the compressor, but nothing will happen because the dual pressure switch has the final say.
So where does the ECU come in? It is wired in series between the thermo control amp and the dual pressure switch (and A/C clutch relay). The ECU acts as a switch itself, intercepting the thermo control amp signal. If you stomp the gas pedal, then the ECU knows you want maximum power, and so it will switch off the A/C temporarily. If your engine overheats, then the ECU may also decide to switch off the A/C temporarily. In either case, the thermo control amp still keeps trying to cycle the compressor, but the ECU won't let it. However, in most cases, the ECU simply acts as a closed switch, allowing the thermo control amp to cycle the compressor.
In some cars, there will also be an FICD. This fast idle control device is just a bypass valve that opens to allow more air into the engine when the A/C kicks on so that the engine idles up. There are different ways to control this, but the simplest way is to just wire it up to the clutch relay. Cars that do not have the FICD (R32 for one) just use the AAC to control idle-up since the ECU already knows that the A/C is coming on.
And then there is climate control. Despite all of the fancy gizmos and additional temperature sensors, the climate control can only tell the A/C system that it is too hot in the car or too cold in the car, just like your house thermostat. If the climate control says that it is too hot, it will try to turn on the A/C. However, control of the compressor clutch still belongs to the thermo control amp, not the climate control unit. And in fact, your compressor will still cycle on and off even when your climate control says it is too hot. Once again, the cycling is necessary to limit the amount of cooling in the evaporator coil to keep it from icing up. Like I said before, if you really want the fancy climate control, you'll have to work that part out on your own. But once you get that figured out, there is only one connection to the rest of the A/C system you need to worry about: one wire goes from the climate control to the thermo control amp.
So there it is in a (big) nutshell. If you are afraid of including the ECU, then just leave it out. As long as you have the dual pressure switch and thermo control amp, you'll be ok. If you don't have an FICD, the engine may bog down at idle, but I'm sure you can live with that.
In my opinion, the ideal setup is the S14 compressor, custom lines, and the stock ECU. The S14 compressor is variable displacement, meaning it actually does have a capacity control so that it does not need to cycle nearly as much. It stays on most of the time and just reduces its capacity when the engine speeds up. It is also easy to find a replacement. However, mounting it to an RB requires a custom bracket. It would be cool if someone with a mill could make one and sell it. My cheap drill press makes a poor substitute for a milling machine.
But first you need to understand how the basic A/C system works on Nissans. Inevitably, problems will arise, and you will be much better off when troubleshooting if you know how things are supposed to work.
I assume most people know about the evaporator, condenser, and dryer. So first off, a list of the major control parts and their functions:
1. A/C clutch. This just engages the drive belt on the compressor. It is actuated by a relay. When the clutch comes on, the A/C gets cold.
2. Triple (or dual) pressure switch. This switch has an overpressure switch, an underpressure switch, and in some cases (triple) another switch that can be used for fan control. This switch is normally closed. The dual pressure part is the important part. If your system pressure gets too high for whatever reason, the overpressure switch will open to protect from explosion or compressor failure. If your system pressure gets too low, usually from leaking refrigerant, the low pressure switch will open to protect the compressor. The dual pressure switch is usually wired directly in series to the A/C clutch relay. This means that no matter how the climate control is working, no matter what the ECU does, no matter what else is going on, if the pressure is too high or too low, the A/C WILL NOT COME ON. Now that you know about the triple pressure switch, forget about it. It is there only for safety, not for control. It DOES NOT cycle the compressor. Unless your system is broken, the triple pressure switch will always be closed.
3. Thermo control amp. This is basically a temperature controlled switch, much like the ones you use to control your radiator fans, but somewhat more sophistocated. This is what "cycles" your compressor on all systems (fully automatic climate control or manual on all S13/S14 and all R32/R33 -- I don't know about R34). The thermo control amp is necessary because in most cases, the compressor does not have a capacity control. It pumps refrigerant based on how fast it is spinning. For example, if you are driving along the interstate at 3000 rpm, then the compressor is pumping a huge amount of refrigerant. With this much refrigerant, it is easy for the evaporator to get too cold and ice up. So the thermo control amp senses the evaporator temperature and sends out a signal when the temperature gets too low. Likewise, when the evaporator gets warm again, the thermo control amp sends out a signal that it is ok for the compressor to switch back on. This is the "cycling" you have heard about. Some cars use a separate low pressure switch to achieve the same thing.
So the basic control scheme is this: You push your A/C button on your dash. The button powers up the thermo control amp. The thermo control amp switches on the A/C clutch and the compressor comes on. You feel cold air. Then, when the evaporator gets too cold, the thermo control amp switches off the A/C clutch. You may feel the air begin to warm up just a tad. Then the thermo control amp switches back on the compressor and the cycle repeats. If the refrigerant pressure gets really, really high or really, really low, then the dual pressure switch opens shutting off the compressor to protect it. Since the thermo control amp knows nothing about the pressure, it might still be trying to cycle the compressor, but nothing will happen because the dual pressure switch has the final say.
So where does the ECU come in? It is wired in series between the thermo control amp and the dual pressure switch (and A/C clutch relay). The ECU acts as a switch itself, intercepting the thermo control amp signal. If you stomp the gas pedal, then the ECU knows you want maximum power, and so it will switch off the A/C temporarily. If your engine overheats, then the ECU may also decide to switch off the A/C temporarily. In either case, the thermo control amp still keeps trying to cycle the compressor, but the ECU won't let it. However, in most cases, the ECU simply acts as a closed switch, allowing the thermo control amp to cycle the compressor.
In some cars, there will also be an FICD. This fast idle control device is just a bypass valve that opens to allow more air into the engine when the A/C kicks on so that the engine idles up. There are different ways to control this, but the simplest way is to just wire it up to the clutch relay. Cars that do not have the FICD (R32 for one) just use the AAC to control idle-up since the ECU already knows that the A/C is coming on.
And then there is climate control. Despite all of the fancy gizmos and additional temperature sensors, the climate control can only tell the A/C system that it is too hot in the car or too cold in the car, just like your house thermostat. If the climate control says that it is too hot, it will try to turn on the A/C. However, control of the compressor clutch still belongs to the thermo control amp, not the climate control unit. And in fact, your compressor will still cycle on and off even when your climate control says it is too hot. Once again, the cycling is necessary to limit the amount of cooling in the evaporator coil to keep it from icing up. Like I said before, if you really want the fancy climate control, you'll have to work that part out on your own. But once you get that figured out, there is only one connection to the rest of the A/C system you need to worry about: one wire goes from the climate control to the thermo control amp.
So there it is in a (big) nutshell. If you are afraid of including the ECU, then just leave it out. As long as you have the dual pressure switch and thermo control amp, you'll be ok. If you don't have an FICD, the engine may bog down at idle, but I'm sure you can live with that.
In my opinion, the ideal setup is the S14 compressor, custom lines, and the stock ECU. The S14 compressor is variable displacement, meaning it actually does have a capacity control so that it does not need to cycle nearly as much. It stays on most of the time and just reduces its capacity when the engine speeds up. It is also easy to find a replacement. However, mounting it to an RB requires a custom bracket. It would be cool if someone with a mill could make one and sell it. My cheap drill press makes a poor substitute for a milling machine.
Re: (Wulfgang)
Thanks ALOT man!! I understood alot about the AC but def not as indepth as that. me using the R33 climate control is not required for me. It was jsut a thought so I'll do somemore research and see if I can find the pinouts but if not I'll stick with the S14 controls. and it seems simple to keep the ECu in the loop, i mean from that diagram it looks like i just do what you said and hard wire the Thermo control amp and then just make sure the wires that run to the ECU are hooked up as they would have been stock.
Oh and my power steering and AC compressor got crack when the car was wreck in japan so i might see if i can get a friend to make me a bracket. to use the S14 compressor. And he has the machinary to might have to start producing that bracket Thanks again man!
Oh and my power steering and AC compressor got crack when the car was wreck in japan so i might see if i can get a friend to make me a bracket. to use the S14 compressor. And he has the machinary to might have to start producing that bracket Thanks again man!
Re: (Ramius83)
yeah you are right with the diagram I just was making sure i understood correctly and that it was the same for the Rb25. thanks for everyones input.
Oh and it looks like I'm going to have nate make me the custom bracket so i can use the stock KA compressor on my Rb25. I'll have to see how many he wants to make might sell a few.
Oh and it looks like I'm going to have nate make me the custom bracket so i can use the stock KA compressor on my Rb25. I'll have to see how many he wants to make might sell a few.
Re: (Ramius83)
Haha, yep, same diagram too. I had forgotten that was you. Here's the thread:Ramius83 wrote:So then again, my diagram up top describes Wulfgangs theory, since we did talk about this in the past......
zerothread?id=93247
... and if you search, there are others just like it.
Re: (Wulfgang)
Sorry for bringing up a old topic. I guess I didn't search well enough. But thanks for taking the time to clear things up!