LS1 Swap AC wiring
06-08-2015, 04:18 PM
#1
LS1 Swap AC wiring Putting a 2002 LS1 and PCM into my 58 Apache pick-up. Vintage Air AC unit
Via this site I've formulated a plan to use the f-body high pressure switch and use the ECM to control the fans. Then I noticed there is also a low pressure switch of some sort for the AC operation? What does this do and are there examples of how to integrate that into the system? Is it needed? Thx.
Via this site I've formulated a plan to use the f-body high pressure switch and use the ECM to control the fans. Then I noticed there is also a low pressure switch of some sort for the AC operation? What does this do and are there examples of how to integrate that into the system? Is it needed? Thx.
06-08-2015, 04:29 PM
#2
TECH Resident
The low pressure switch makes sure there is a minimum amount of refrigerant in the system. Without that, you'd burn up the compressor if you energized the clutch to drive the compressor.
I'm not sure how it is wired with LS1. With some, the low pressure switch is wired inline with the compressor 12V+ feed to the compressor clutch. If the low pressure condition is not met, the switch will not pass current (open).
In some applications, the computer will also kill power to the compressor clutch above a certain RPM. (the compressor shouldn't be spun too fast.)
For these reasons and those mentioned about the fan control, it's great to use the computer to control the AC compressor clutch.
I'm not sure how it is wired with LS1. With some, the low pressure switch is wired inline with the compressor 12V+ feed to the compressor clutch. If the low pressure condition is not met, the switch will not pass current (open).
In some applications, the computer will also kill power to the compressor clutch above a certain RPM. (the compressor shouldn't be spun too fast.)
For these reasons and those mentioned about the fan control, it's great to use the computer to control the AC compressor clutch.
06-08-2015, 04:52 PM
#3
dunce79,
In my '00 - '02 Fbody GM AC schematic, I see do not a high or low pressure switch, only the A/C refrigerant pressure sensor. When I installed my after market A/C system (Hot R0d Air), I simply wired in the Fbody pressure sensor into the PCM, and wired in the request wire from the A/C unit to the PCM A/C request signal (C2, pin 17). Works great. I suspect your binary (or trinary) switch on your Vintage system is already wired in, so you'll have to remove it if you choose to use the GM pressure sensor. BTW, I love how the PCM controls the fans, idle bump up, etc.
Andy1
In my '00 - '02 Fbody GM AC schematic, I see do not a high or low pressure switch, only the A/C refrigerant pressure sensor. When I installed my after market A/C system (Hot R0d Air), I simply wired in the Fbody pressure sensor into the PCM, and wired in the request wire from the A/C unit to the PCM A/C request signal (C2, pin 17). Works great. I suspect your binary (or trinary) switch on your Vintage system is already wired in, so you'll have to remove it if you choose to use the GM pressure sensor. BTW, I love how the PCM controls the fans, idle bump up, etc.
Andy1
06-08-2015, 04:57 PM
#4
I think I got confused by looking at a harness from another engine. I don't think there is a low pressure circuit either on the 2002 LS1. only the one you mention with the AC pressure sensor on pressure side of the system, so I should be good. Still in the design stages now, so nothing to redo just yet thankfully. Using the ECM to control things sure sounds like the way to go.
dunce79,
In my '00 - '02 Fbody GM AC schematic, I see do not a high or low pressure switch, only the A/C refrigerant pressure sensor. When I installed my after market A/C system (Hot R0d Air), I simply wired in the Fbody pressure sensor into the PCM, and wired in the request wire from the A/C unit to the PCM A/C request signal (C2, pin 17). Works great. I suspect your binary (or trinary) switch on your Vintage system is already wired in, so you'll have to remove it if you choose to use the GM pressure sensor. BTW, I love how the PCM controls the fans, idle bump up, etc.
Andy1
In my '00 - '02 Fbody GM AC schematic, I see do not a high or low pressure switch, only the A/C refrigerant pressure sensor. When I installed my after market A/C system (Hot R0d Air), I simply wired in the Fbody pressure sensor into the PCM, and wired in the request wire from the A/C unit to the PCM A/C request signal (C2, pin 17). Works great. I suspect your binary (or trinary) switch on your Vintage system is already wired in, so you'll have to remove it if you choose to use the GM pressure sensor. BTW, I love how the PCM controls the fans, idle bump up, etc.
Andy1