A/C request Blue/Green connector ECU
10-17-2015, 06:33 PM
#41
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Sweet, I got the A/C to work finally..havent had time till now to get back into it. Grounded C2 pin 55 and the compressor came right on. And yeah, no fans, and i know my tuner set the pressures i stood there and watched him...Ill have to go back and have him look at that fans disable speed. Im glad you found it, i was gettin to the point of installing a trinary switch or a fan switch just to turn em on.
SO to clarify, ive got an 03 truck ECM with a stock tune. I kept the stock pressure sensor and had it grafted into my high pressure line.
C2 pin 55 ground
pin 17 12v A/C request
pin 43 relay control, grounds the A/C clutch relay
Set compressor control to analog, adjust fan pressures as necessary and set fans disable speed to 40-60mph.
This is all pending your using the stock pressure sensor, not the switch, the 3 pin sensor.
Mark
SO to clarify, ive got an 03 truck ECM with a stock tune. I kept the stock pressure sensor and had it grafted into my high pressure line.
C2 pin 55 ground
pin 17 12v A/C request
pin 43 relay control, grounds the A/C clutch relay
Set compressor control to analog, adjust fan pressures as necessary and set fans disable speed to 40-60mph.
This is all pending your using the stock pressure sensor, not the switch, the 3 pin sensor.
Mark
11-13-2015, 11:07 AM
#42
You can change your a/c request type up to a point. You can change between serial and analog or between analog cycling and serial cycling. You cannot change from serial to analog cycling or serial cycling to analog. HPTuners will let you make the change but the PCM will not function with it. I have no idea what the "passive" option does.
05-02-2016, 09:48 PM
#43
Ok, so I'm back at this again..... What I have now is a 2004 Silverado 6.0, and rewired the A/C back to the way it was originally in the '04 with the three wire pressure sensor. I added the wire for the 12v A/C request and just want to know what exactly to set the parameters to in the tune. I know it was serial originally, and need to change it to analog, but is it "analog cycling"? Basically all I want to do is add the 12v request to an '04 Silverado.
05-03-2016, 08:45 AM
#45
Ok, so I'm back at this again..... What I have now is a 2004 Silverado 6.0, and rewired the A/C back to the way it was originally in the '04 with the three wire pressure sensor. I added the wire for the 12v A/C request and just want to know what exactly to set the parameters to in the tune. I know it was serial originally, and need to change it to analog, but is it "analog cycling"? Basically all I want to do is add the 12v request to an '04 Silverado.
05-04-2016, 09:26 PM
#46
TECH Enthusiast
Guys if you are using the stock wiring setup for a fixed compressor and the stock PCM then it should work for you. There is no pressure sensor on a fixed compressor they are only on the variable. The A/C request is pin 17 this comes from the control panel. All the old GM vehicles work the same way were the proper panel selection will send 12 volts to turn on the a/c. Both fixed and variable compressors use this pin to turn on the system. The main difference between a variable compressor and a fixed is that the fixed cycles and the variable does not. They are wired differently because they function differently. The high pressure switch is to turn off the compressor on the fixed compressor. The low pressure is only a fail safe to make sure there is enough R134 in the system to so it does not burn up the compressor. Variable compressors are made to run all the time and use the pressure sensor to control the on/off of the compressor and the second fan high/low speed. The on/off is only for the same conditions described above which it is never supposed to see unless there is something wrong with the system. Follow the diagram I have inserted. If you guys are trying to change the compressor type in HP tuners I have been told it does not work. I cannot verify EFI either since I use TunerCat.
05-05-2016, 07:00 AM
#50
TECH Resident
I believe there is a physical issue with the different computers. We had one the other day with a 2004 computer that was wired with the A/C request to 17, low pressure to 55, relay control on 43, and it worked fine.
We loaded the exact same program in to another computer, and it wouldn't work. We tried a couple different part number computers for '03-'05 and finally concluded that just like an electronic throttle Blue/green ECU won't physically operate the IAC valve on a cable throttle body, it is the same with the A/C.
The only blue/green computers that we could run electronic throttle and A/C wired through the computer were also compatible with cable throttle. So computers from vehicles like vans, V6 S10's, Blazers, and V6 full size trucks seemed to be the only way it worked.
We loaded the exact same program in to another computer, and it wouldn't work. We tried a couple different part number computers for '03-'05 and finally concluded that just like an electronic throttle Blue/green ECU won't physically operate the IAC valve on a cable throttle body, it is the same with the A/C.
The only blue/green computers that we could run electronic throttle and A/C wired through the computer were also compatible with cable throttle. So computers from vehicles like vans, V6 S10's, Blazers, and V6 full size trucks seemed to be the only way it worked.
05-05-2016, 07:44 AM
#52
I believe there is a physical issue with the different computers. We had one the other day with a 2004 computer that was wired with the A/C request to 17, low pressure to 55, relay control on 43, and it worked fine.
We loaded the exact same program in to another computer, and it wouldn't work. We tried a couple different part number computers for '03-'05 and finally concluded that just like an electronic throttle Blue/green ECU won't physically operate the IAC valve on a cable throttle body, it is the same with the A/C.
The only blue/green computers that we could run electronic throttle and A/C wired through the computer were also compatible with cable throttle. So computers from vehicles like vans, V6 S10's, Blazers, and V6 full size trucks seemed to be the only way it worked.
We loaded the exact same program in to another computer, and it wouldn't work. We tried a couple different part number computers for '03-'05 and finally concluded that just like an electronic throttle Blue/green ECU won't physically operate the IAC valve on a cable throttle body, it is the same with the A/C.
The only blue/green computers that we could run electronic throttle and A/C wired through the computer were also compatible with cable throttle. So computers from vehicles like vans, V6 S10's, Blazers, and V6 full size trucks seemed to be the only way it worked.
05-05-2016, 08:49 AM
#53
TECH Resident
I just changed the setting to Analog Cycling, and set my enable and disable settings for RPM and TPS. That was it.
We loaded the exact same file in to multiple computers, and the only ones that would work were the computers that were capable of also functioning in cable throttle applications.
I also connected a scanner to it to watch the A/C request signal. On the computers that would't work, the OS never even recognized the request coming in to the computer, but on the one's that did, as soon as we supplied voltage to pin 17, the OS immediately reported that the A/C was being requested. So this makes me think there is a physical component missing that links pin 17 to the processor so it can see the request. probably just a resistor on the board.
We loaded the exact same file in to multiple computers, and the only ones that would work were the computers that were capable of also functioning in cable throttle applications.
I also connected a scanner to it to watch the A/C request signal. On the computers that would't work, the OS never even recognized the request coming in to the computer, but on the one's that did, as soon as we supplied voltage to pin 17, the OS immediately reported that the A/C was being requested. So this makes me think there is a physical component missing that links pin 17 to the processor so it can see the request. probably just a resistor on the board.
05-05-2016, 09:00 AM
#54
TECH Enthusiast
OK. Sorry I forgot about this. I believe there is a difference between the 04 242 and 243 PCM's that somebody found out about accidently on the 240SX forum and one will work and the other will not. The newer 05-07 PCM's I believe end in 502 and 503 or something like that will do it all which is what I am running but I will have to confirm which one is the one to get. Also depending on if you are running a cable or wire TB it will matter because you will need the IAC drivers that some do not include for a cable TB. The safe PCM is to get the one with the IAC drivers if you need a new PCM and they will work on all 03 to 07 OS's using the Blue/Green PCM's. I have a line on a guy that sells them for a very reasonable price and will program it with the OS that you want if needed. On another note below is a very good thread on A/C systems this is written for a GTO so this is a variable compressor setup that is run by the BCM if you wire it like a 02 Camaro it works also. This is the setup I am using. Note that no matter what anybody else says you CAN use a variable compressor setup on any ac system including Vintage Air. I had it on my car before I went to a factory unit. Do not believe what you hear the only difference is how they are controlled. They work for both orifice tubes and TVX systems. Sandens are not better compressors than factory GM units again they want to sell you something. You will get into all the other crap like new mounts and everything else if you go that route. It is best to keep what you got on your motor and make that work with what you have on the other end.
http://www.ls1gto.com/forums/showthread.php?t=381879
http://www.ls1gto.com/forums/showthread.php?t=381879
05-05-2016, 08:46 PM
#55
I just changed the setting to Analog Cycling, and set my enable and disable settings for RPM and TPS. That was it.
We loaded the exact same file in to multiple computers, and the only ones that would work were the computers that were capable of also functioning in cable throttle applications.
I also connected a scanner to it to watch the A/C request signal. On the computers that would't work, the OS never even recognized the request coming in to the computer, but on the one's that did, as soon as we supplied voltage to pin 17, the OS immediately reported that the A/C was being requested. So this makes me think there is a physical component missing that links pin 17 to the processor so it can see the request. probably just a resistor on the board.
We loaded the exact same file in to multiple computers, and the only ones that would work were the computers that were capable of also functioning in cable throttle applications.
I also connected a scanner to it to watch the A/C request signal. On the computers that would't work, the OS never even recognized the request coming in to the computer, but on the one's that did, as soon as we supplied voltage to pin 17, the OS immediately reported that the A/C was being requested. So this makes me think there is a physical component missing that links pin 17 to the processor so it can see the request. probably just a resistor on the board.
You wouldn't happen to have a PCM service number of one that works would you? If it's just a blue/green PCM with IAC drivers I suppose I could google 2005ish Express van and find out what they use since they were cable throttle body.
05-08-2016, 05:53 PM
#56
So after trying every different combination there was in HPT, my A/C still doesn't work. But I "think" I may have it figured out. What Jones'n said about only the PCM's that would run a cable throttle body will work and 69 Ghost saying that a 6242 PCM wouldn't work but a 6243 would, say the same thing. The 6243 PCM is a 2004 Express van PCM and it has IAC drivers in it, and since vans all had 12v request that year, there must be another physical part on the board that allows the 12v request to work. So I'm getting a 6243 PCM and am going to set it to analog cycling and it "should" work. I'll keep everybody posted.
06-11-2016, 12:39 AM
#57
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Little more info...after grounding pin 55 it worked as i stated above...but ive still got a fan issue. Set the AC fan disable MPH to 50 from zero and the fans still wont come on when the ac goes over said pressure. I need to get back to my guy with HP tuners and figure out what we missed. Fans work great otherwise, just not by AC pressure
06-11-2016, 12:05 PM
#58
TECH Enthusiast
The fan portion is separate on the OS. You can set it to 0,1, or 2 fans. Trucks, etc did not have electric fans. You need to program the number of fans and wire the fans accordingly depending on what you have. The Camaros have 2 fans with high-low that uses 3 relays. Basically the low is one fan coming on. The GTO has 2 fans where one is controlled by the bcm. The only difference is how it is wired. If you are using 2 fans probably the best solution is to use the Camaro 3 relay setup so both fans run.
07-04-2016, 02:28 PM
#59
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Im using a single ford 2 speed fan with 2 relays. It works great normally hi and low speeds controlled by the ECU. But I dont know what I missed to have it work with ac pressure above 250psi. Ive got to spend a min and go back to my tuner so we can go through the settings again. I just havent had a minute and now its hot...so yeah gotta get this taken care of
07-22-2016, 09:50 AM
#60
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Fixed! Originally had to change the compressor control from serial data to analog cycling to make the compressor come on with a simple ac request 12v. But the fans would never work when the high side got to the set point. Changed analog cycling to analog and it works fine now. Go figure. What's the difference in analog vs. analog cycling? Other than the electric fans not working.