Anyone made A/C AND Fans work with Blue/ Green PCM?
08-14-2023 | 11:11 AM
#21
There is a lot to it, this site has the most comprehensive information that I've seen on the challenges especially with blue/green P59s as only a few service numbers will work using a 12V a/c request.
https://lt1swap.com/airconditioning.htm
https://lt1swap.com/airconditioning.htm
08-15-2023 | 07:53 AM
#22
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Joined: Jul 2019
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sorry to bug you guys, but I have the same problem (and the tuner doesn't care apparently to fix it).Is a P59 on a 2003 truck and I converted to electric fans. Fans work flawlessly as the ect goes up, no problem. A/C operation is the issue. On A/C request, compressor clutch activates like normal, HP sensor reads around 1.5V and starts to go up (close to 4V), condenser gets super hot, but no fan kicks on. It just doesn't respond to A/C HP sensor. Recirculation fitted is set to "Fan # 2" and Type fitted is set to "serial cycling". is this correct? truck has factory 3 wire pressure sensor on high side.
I contacted the tuner and ask for a new file, they emailed me one, but they only changed ON/OFF temps under fan setting (which seems irrelevant to the issue) and I can't even write to ECM, keep asking for a license. Is this sounds right? Tuner "theoretically" used one or two credit for this VIN, why asking for license again? Appreciate any input.
I contacted the tuner and ask for a new file, they emailed me one, but they only changed ON/OFF temps under fan setting (which seems irrelevant to the issue) and I can't even write to ECM, keep asking for a license. Is this sounds right? Tuner "theoretically" used one or two credit for this VIN, why asking for license again? Appreciate any input.
08-15-2023 | 12:07 PM
#23
Staging Lane
Joined: May 2019
Posts: 72
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From: Northern VA
Is a factory denso 10s17f compressor and is a fixed displacement to best of my knowledge. So you think if I change it to “serial” it’ll command the fan on a/c?then compressor will not cycle? This became frustrating for real…
08-16-2023 | 09:51 AM
#24
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As for the fan operation, the original post seems to indicate that with the O/S you are using, you need to set the A/C system to non cycling in order for the fans to come on with A/C pressure:
"With an analog cycling setup, the PCM monitors the low pressure switch signal. The AC request signal is sent from the HVAC controls, through the high pressure switch, and then to the PCM. There is no pressure sensor on a cycling setup. When the PCM is setup for cycling, it will not command the fans based on AC refrigerant pressure, but it will command the fans for engine coolant temp.
With a non-cycling setup, the PCM monitors a pressure sensor mounted on the high side. It does not use any pressure switches. When setup as non-cycling, the PCM will command the fans on based on AC refrigerant pressure as well as engine coolant temp."
If you change this and it works as expected, please let us know as that is useful feedback.
08-16-2023 | 12:37 PM
#26
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you could also try swapping to the 2004 or 2005 OS. The 2005 would've had e-fans by default, and as far as i can tell it was still set up for "serial cycling" in the tune.
08-16-2023 | 01:01 PM
#27
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From: Euless, TX
08-16-2023 | 01:37 PM
#28
Teching In
Joined: Jul 2023
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I had the same exact issue as @Nariman, I ended up resolving the issue by installing a pressure sensor and setting the pcm to analog (not analog cycling). I kept the high and low pressure switches as they were already installed and I just had to adjust some of the wiring.
My setup is p59 pcm that is analog request capable, denso 10s17f compressor, AC set to Analog with pressure sensor and low and high pressure switches.
My setup is p59 pcm that is analog request capable, denso 10s17f compressor, AC set to Analog with pressure sensor and low and high pressure switches.
09-04-2023 | 10:20 AM
#29
Staging Lane
Joined: May 2019
Posts: 72
Likes: 5
From: Northern VA
So, for any of you guys may be interested, I was able to make it work. The problem was the 20 year old pressure sensor, tune and also the HVAC head inside. No other modifications in wiring or anything else. Blue/green ECU. Serial cycling. reads pressure from pressure sensor on high side (as stock) and responds to it accordingly with low or high fan speeds, depending on ECT input. works and cycles as it should.
11-06-2023 | 10:43 AM
#30
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So, for any of you guys may be interested, I was able to make it work. The problem was the 20 year old pressure sensor, tune and also the HVAC head inside. No other modifications in wiring or anything else. Blue/green ECU. Serial cycling. reads pressure from pressure sensor on high side (as stock) and responds to it accordingly with low or high fan speeds, depending on ECT input. works and cycles as it should.
