Sanden 508 Wiring and PCM Tuning?
06-07-2016, 04:40 PM
#1
Sanden 508 Wiring and PCM Tuning? Hey everyone, I'm researching like mad right now but I figured someone out there may have a silver bullet for this issue... 
I've got a 2000 Isuzu Hombre with an LS1/T56 that I'm trying to get AC set up on for the Hot Rod Power Tour... in 4 days. The compressor is a Sanden 508, the PCM is for a 2000 Fbody and the wiring harness is BP Automotive. The harness is top notch, but when I ordered it, I said I'd run an Fbody compressor. Well, I couldn't get the frame notch large enough, so I had to go with the Sanden.
The truck is at the AC shop now, they've got lines fabricated/installed and the system held vacuum, so they're filling it shortly. But they say they can't get the compressor to stay engaged for more than a second or so.
So far, I've read that one issue is that the FBody cars used a pressure transducer rather than a low and/or high pressure switch. The BP Automotive harness has a 3 wire plug for a switch just after (or before, it's near) the dryer and a two wire plug for the compressor. The two wire portion was easy, send the black to ground and the green to the single wire of the compressor.
To run this compressor, is there an adjustment in the PCM I need to make? Or is there a switch we need to add or replace?
Thanks in advance, sorry for the essay! Here's a pic to ease the pain hopefully.
I've got a 2000 Isuzu Hombre with an LS1/T56 that I'm trying to get AC set up on for the Hot Rod Power Tour... in 4 days. The compressor is a Sanden 508, the PCM is for a 2000 Fbody and the wiring harness is BP Automotive. The harness is top notch, but when I ordered it, I said I'd run an Fbody compressor. Well, I couldn't get the frame notch large enough, so I had to go with the Sanden.
The truck is at the AC shop now, they've got lines fabricated/installed and the system held vacuum, so they're filling it shortly. But they say they can't get the compressor to stay engaged for more than a second or so.
So far, I've read that one issue is that the FBody cars used a pressure transducer rather than a low and/or high pressure switch. The BP Automotive harness has a 3 wire plug for a switch just after (or before, it's near) the dryer and a two wire plug for the compressor. The two wire portion was easy, send the black to ground and the green to the single wire of the compressor.
To run this compressor, is there an adjustment in the PCM I need to make? Or is there a switch we need to add or replace?
Thanks in advance, sorry for the essay! Here's a pic to ease the pain hopefully.
06-07-2016, 05:49 PM
#2
Still researching, looks like my 2000 Isuzu Hombre has a pressure transducer as opposed to a high and/or low pressure switch. It appears to be the same connector as that on my '02 Camaro. To me, that means all the wiring is right as long as that sensor is connected and my compressor is wired with the one wire to the green from the two pins from the PCM.
Huh, so, PCM control changes? The shop says it's not throwing any codes...
Edit: I looked up the stock AC compressor for a 2000 Isuzu Hombre and one for a 2002 Camaro. The Four Seasons P/Ns are 68288 for the Camaro and 68291 for the Hombre... the plugs are identical, they're both "V7" and other than mounting bosses, I'd say they're identical. If the 02 Camaro only uses the 3 wire switch and so does the Hombre, presumably I have no additional wiring to do as long as the wires to the switch are correct. So, what in the PCM could be holding the shop back?
Huh, so, PCM control changes? The shop says it's not throwing any codes...
Edit: I looked up the stock AC compressor for a 2000 Isuzu Hombre and one for a 2002 Camaro. The Four Seasons P/Ns are 68288 for the Camaro and 68291 for the Hombre... the plugs are identical, they're both "V7" and other than mounting bosses, I'd say they're identical. If the 02 Camaro only uses the 3 wire switch and so does the Hombre, presumably I have no additional wiring to do as long as the wires to the switch are correct. So, what in the PCM could be holding the shop back?
Last edited by themealonwheels; 06-07-2016 at 05:59 PM.
06-08-2016, 07:35 AM
#3
Bumping this up for any input. It seems my Isuzu Hombre has the "Camaro" pressure sensor, which is appropriately wired to the PCM in Red/Black, grey and purple wiring. So if the Sanden compressor is powered and the ground of the two wires to the compressor is appropriately grounded, the only significant difference from a stock Camaro arrangement is the fact that the Sanden 508 compressor is fixed displacement. I'm stumped as to why it comes on and shuts off.
Two days til we pack up for the Hot Rod Power Tour, any help is appreciated!
Two days til we pack up for the Hot Rod Power Tour, any help is appreciated!
06-08-2016, 07:40 AM
#4
as posted recently on another thread by '69 Ghost'
"If you are looking to control your vintage air system that is a complete VA system which means a FIXED compressor you want to keep the system you have and program the PCM to accept a fixed compressor type. The sensor is for a variable system that is not made to cycle. This info has been repeated over and over again. GM used different types of compressors on different types of vehicles. All types work. The difference is fixed compressors use a pressure switch that turns the compressor on and off. The pressure sensor is used when the compressor (variable) does not cycle. It controls the fan speeds. Both types will bump the idle and set the fans when programmed properly. "
I suspect your wiring and pressure switch are for a variable compressor and you now have a fixed compressor which you can wire up per Vintage Air's diagrams with either a binary or trinary switch. or you might try reprogramming the pcm for fixed type compressor first.
"If you are looking to control your vintage air system that is a complete VA system which means a FIXED compressor you want to keep the system you have and program the PCM to accept a fixed compressor type. The sensor is for a variable system that is not made to cycle. This info has been repeated over and over again. GM used different types of compressors on different types of vehicles. All types work. The difference is fixed compressors use a pressure switch that turns the compressor on and off. The pressure sensor is used when the compressor (variable) does not cycle. It controls the fan speeds. Both types will bump the idle and set the fans when programmed properly. "
I suspect your wiring and pressure switch are for a variable compressor and you now have a fixed compressor which you can wire up per Vintage Air's diagrams with either a binary or trinary switch. or you might try reprogramming the pcm for fixed type compressor first.
Last edited by 04Z06vette; 06-08-2016 at 07:42 AM. Reason: more data
06-08-2016, 08:44 AM
#5
as posted recently on another thread by '69 Ghost'
"If you are looking to control your vintage air system that is a complete VA system which means a FIXED compressor you want to keep the system you have and program the PCM to accept a fixed compressor type. The sensor is for a variable system that is not made to cycle. This info has been repeated over and over again. GM used different types of compressors on different types of vehicles. All types work. The difference is fixed compressors use a pressure switch that turns the compressor on and off. The pressure sensor is used when the compressor (variable) does not cycle. It controls the fan speeds. Both types will bump the idle and set the fans when programmed properly. "
I suspect your wiring and pressure switch are for a variable compressor and you now have a fixed compressor which you can wire up per Vintage Air's diagrams with either a binary or trinary switch. or you might try reprogramming the pcm for fixed type compressor first.
"If you are looking to control your vintage air system that is a complete VA system which means a FIXED compressor you want to keep the system you have and program the PCM to accept a fixed compressor type. The sensor is for a variable system that is not made to cycle. This info has been repeated over and over again. GM used different types of compressors on different types of vehicles. All types work. The difference is fixed compressors use a pressure switch that turns the compressor on and off. The pressure sensor is used when the compressor (variable) does not cycle. It controls the fan speeds. Both types will bump the idle and set the fans when programmed properly. "
I suspect your wiring and pressure switch are for a variable compressor and you now have a fixed compressor which you can wire up per Vintage Air's diagrams with either a binary or trinary switch. or you might try reprogramming the pcm for fixed type compressor first.
06-08-2016, 12:21 PM
#6
Alright, I ran out to the car to look at my AC options. I found it's currently on Analog, but there was an option for Analog Cycling. That must be what I need to switch it to, so that's one task down...
However, will the existing sensor return a signal to cycle the compressor appropriately? I'm guessing not, which is why I went ahead and told the shop they should plan on installing a low pressure switch. They came back with where it would be installed, at the compressor or the dryer.
So what switch should they install for the low pressure? '02 Express Van? Where should it be installed?
However, will the existing sensor return a signal to cycle the compressor appropriately? I'm guessing not, which is why I went ahead and told the shop they should plan on installing a low pressure switch. They came back with where it would be installed, at the compressor or the dryer.
So what switch should they install for the low pressure? '02 Express Van? Where should it be installed?
06-10-2016, 07:21 AM
#7
Wow, I feel like I'm talking to myself on this topic, but for future reference...
I spoke with 69Ghost, he was really knowledgeable on the subject. Turns out in 2000, 4cyl S10s (like an Hombre) were variable displacement compressor units, while the V6 counterparts were fixed displacement. Since the Sanden 508 is fixed displacement, there's no getting around that I need to replace my sensor arrangement with a high and low pressure switch arrangement. Rather than refab the lines the shop made, we bought a dryer/accumulator and high PSI switch for a 2000 V6 S10. It bolted right in and incorporates the high PSI switch in the accumulator.
Unfortunately, I'm on a deadline for the Hot Rod Power Tour and had to settle up before they could charge the system, but I'm basically a charge, some wiring and an OS change/tune away from an operating system! I think... it will be addressed after the tour.
I spoke with 69Ghost, he was really knowledgeable on the subject. Turns out in 2000, 4cyl S10s (like an Hombre) were variable displacement compressor units, while the V6 counterparts were fixed displacement. Since the Sanden 508 is fixed displacement, there's no getting around that I need to replace my sensor arrangement with a high and low pressure switch arrangement. Rather than refab the lines the shop made, we bought a dryer/accumulator and high PSI switch for a 2000 V6 S10. It bolted right in and incorporates the high PSI switch in the accumulator.
Unfortunately, I'm on a deadline for the Hot Rod Power Tour and had to settle up before they could charge the system, but I'm basically a charge, some wiring and an OS change/tune away from an operating system! I think... it will be addressed after the tour.
Trending Topics
06-10-2016, 02:06 PM
#9
Since I'm here, I might as well update as I've learned another critical bit of info... I mentioned the high PSI switch at the accumulator. 69Ghost gave me a wiring diagram for an '03 S10 that specifically says the high PSI switch is at the back of the compressor and that the LOW PSI switch is at the accumulator. Glad he brought that to my attention, now I have to figure out how to incorporate a high PSI switch on the high pressure side of a Sanden 508...
06-11-2016, 06:32 PM
#10
The high pressure sensor can be anywhere in the high side, basically from the compressor to right before the orifice tube. Im using a condenser from a 98 Chevy truck in my 72 and it has a fitting on one of the lines on it, not sure if the S10 stuff is the same but might be worth a look.
06-12-2016, 12:34 PM
#11
TECH Enthusiast
S10 setups have a lot of desirable qualities. The 96-04's used both types of compressors fixed and variable. Four bangers were variable and V6's were fixed. Parts are plentiful and cheap. You can plug and play as needed. S10 condensers work well with older Camaros and Novas where space can be an issue. Here is where it gets interesting. They make 2 different accumulators and hard lines for them. The hard lines come with or without a sensor port. The accumulators come with or without the low pressure switch port. You can adapt as needed. This means if you can make those parts work you can adapt them to any setup. Most guys find that their main problem is fitting issues with the compressor. Make that fit and adapt as needed at the hoses. Orifice tube or valve setups are not the issue. They work with both types of compressors. When people say variables do not work with a vintage air or even a old factory unit they do not know what they are talking about. Vendors will say that to sell you another compressor or they don't want to deal with the wiring differences. I have stated many times the differences are how they are controlled. Variables are made not to cycle and use a sensor. Fixed use pressure switches to cycle the compressor. The compressor types are taken care of in the programming and wiring. You can change the type based on your OS for all Red/Green or Blue/Green PCM's.
Last edited by 69 Ghost; 06-12-2016 at 12:59 PM.
06-13-2016, 08:54 PM
#12
Yeah, thank you gentlemen, I intend to come back and describe the final solution once the tour is done and I can get it all put together. In the meantime, I look forward to posting a picture of my rudimentary temp ac system lol... here's a teaser, it involves 10lbs of ice every hour 
06-20-2016, 12:19 PM
#13
Tour is done, here's what we were working with for A/C lol... lasted about 45-60 minutes at a time, and the hotels provided the "refrigerant" daily! We hauled around 40lbs of fresh ice everywhere we went and I've never drank so much water in a day. Time to get the A/C finished... got a tune from an 02 Express van from an HPTuners rep on the tour.
06-20-2016, 03:04 PM
#15
On The Tree
Join Date: Jun 2016
Location: Central MN
Posts: 166
Likes: 0
Received 0 Likes
on
0 Posts
That's why wife and we live in central MN, it's not near as warm up here but its god awful humid