OBS Chevy Truck LS Engine Swap Single Wire AC Wiring Troubleshoot and Fix + Electric FAN!
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- เผยแพร่เมื่อ 20 ก.ค. 2022
- It's over 100 degrees for the 2nd week in a row here in North Texas. Summer is here and it is HOT! So, to be able to enjoy my LS Swapped 1991 OBS, the a/c has to work. Otherwise, the wife will not go anywhere with me and the truck will sit until it gets a bit cooler outside. If you are in the same situation, fear not! Working a/c is possible. Check out how the compressor is wired up to be functional and the cooling fan will come on at the same time. Every swap is a bit different, but this is how I made this system work on this '91 OBS. The same principal will work on a variety of vehicles, so if you don't drive a 88-98 Chevy truck, that's ok, this can work on any LS swapped vehicle.
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#lsswap #lsobs #obs #88-98chevytruck #lsairconditioning #lsswapac - ยานยนต์และพาหนะ
You verify wht I had been thinking about for over a week
We thank you! I’m in the process of starting my LS OBS Swap. Your videos are super detailed and definitely giving me the confidence to tackle this myself. Thanks for all you do!
Thank you for the kind words. Good luck on your project!
Nice! Great video! I have a similar setup. I can’t wait to see if this will work for mine. I also wired up my MIL light and the check engine light is still on. Looking forward to your next video to see how you fix that problem.
Thank you for the kind words. Let me know if it works. Good luck!
You can use pin 43 red to use for ground signal from computer to kick on e fans an you won’t have to jump compressor wires
Just remember that if you dont have pressure in the system the circuit will not work till you do have pressure so you will need to jump the pressure switch at the accumulator JUST AS A TEST
Nice job. Thanks for all you do. The fan relay fuse block were did you get that from and is it water proof ?
I got the waterproof fuse block from Amazon: www.amazon.com/gp/product/B07MR64XK1/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&th=1
Im confused. At 3:39 Pin 17 goes tied into all the dark green wires, to the compressor, the accumulator and, the ac switch in the cockpit?
Hey brother. Thanks for all the help with the wiring. If we don’t have electric fans, where do I wire the blue wire in the AC relay? Instead of tying it into the fans (since I don’t have them), where does it go for this same set up to work?
Just keep the fan wires tucked away for possible future use. That’s what I did on the ‘91. I had not planned to use the fans, but later decided to use them. Worked out very well. I found that the ‘91 needed extra airflow under hood to keep the temps low enough not to overheat. You can leave yours as is and the relay will not function.
Can I ask what harness you used for the compressor it self where do you connect that one black wire that comes on the compressor ?
I made a video of how I got the a/c working. If you will check my library, it was 9-11 months ago. It would provide more detail than I can go into here. Thanks for asking.
You are missing (or didn’t mention) the input from the high pressure switch on the back of the compressor. The pressure switch on the accumulator is the low pressure switch. The low pressure switch does most of the decision making in terms of cycling on/off and you’ll probably be ok without the high pressure switch. BUT the high pressure switch basically exists to stop your compressor from blowing itself apart in high heat / overcharged conditions. If your compressor fails quickly, I would get the high pressure switch wired in.
If you bought a brand new compressor they don’t come with the high pressure switch so you might not have even thought about it. It’s a simple two wire on / off input to the ecu so it’s either two pins on the ecu, or 1 pin and one ground.
Thanks, I don't have a pressure switch on the compressor. I'll look into it.Thanks for watching.
@@laurencevillegarage They come new with a plug and circlip where the high pressure switch normally goes. Should be a recessed hole on the back of the compressor
@@laurencevillegarage &@ actually that comprey its running direct to 12 volts, No pression sensor’s???
I don't think the LS style a/c compressors have a high pressure switch in the aft end. And the 1991 trucks came with a R4 compressor running R12 refrigerant. Most of the R12 systems did not use a high pressure switch but instead used a high pressure relief valve which blew off into the atmosphere when output pressure from the compressor exceeded a preset value. The original a/c wiring obviously did not run to a computer but instead went through the low pressure switch on the accumulator then to the compressor clutch. Should be able to tie in the trigger wire at the low pressure switch, then run to the ECM pin 17. Most of the ECM ouputs are actually grounds to make circuits complete. Pin 55 may not be needed if the ECM is appropriately programmed for number of fans, a/c, etc.
Does the a/c pump clear the frame rail? Just curious planning on putting one together
The factory LS AC pump will not fit in the factory location. It is too large. The dirty dingo short sanden AC pump will fit. However, modification is required to the side of the frame rail. Check my other videos, I have one showing the install of the dirty dingo compressor.
How has it been running after you completed this setup? In watching I noticed one thing that you might have an issue with. You run the fan relay power on the compressor side of the low pressure switch. If the compressor cycles and the switch cuts out you'll cut power to the fans. I believe you would want the fans running at all times when the AC is activated. If you've noticed your fans turning on and off you might consider moving that power circuit for the fan relay to the constant side of the low pressure switch so that the fans run at all times.
Thanks for the comment, I’ll keep that in mind. So far, I’ve had no issues with the AC. It works great.
I tough the activation came from light green wire , then goes to cycle switch, then to pcm,
It all depends on how the a/c is activated. There can be several ways and it also depends on which pcm is used.
Did you have to bump up the idle for adding AC?
I got it set to idle at 700 rpm and it works just fine with turning on the a/c.
On your 95, you wired the AC in a little differently, which method would you recommend using?
Well, on the '95 I retained the R4 compressor, so it was easier (and more economical at the time) to continue to use what I already had that worked. The factory wiring worked, and just needed a trigger to function. It all depends on what you have to begin with and how much of it works already. There are pros and cons to both. The main disadvantage to using the existing R4 as I did is that you don't get the additional functions of the LS pcm that "can" work with the a/c. Advantage obviously being $ and simplicity of wiring. Advantage to the LS 1 wire style sanden compressor is that (I believe) functions better than an R4 and, when wired properly, provides additional features such as a/c clutch goes into neutral under WOT, adjusts idle on start up to compensate the added drag, and more. Let what you have that works and your wallet be your guide. Both are nice. I chose to use the Dirty Dingo setup because, 1) I wanted the a/c down low out of the way. R4 takes up a lot of space, 2) Have never seen one on an OBS and wanted to try it, and 3) my existing system had not been used in a long time and no way to determine if it worked at all.
@@laurencevillegarage That makes complete sense. Thank you for the reply!
did you add a high pressure safety cuto off on the condensor?
It is on my never ending list of to do's to finally complete the truck. Good eye.
@@laurencevillegarage I'm doing a. 508 swap on. My tbi and using a95 condenser it has a threaded port for one
Why do u still have the OBS computer in your truck?
What is it running.
I totaly removed mine and the harness to it.
I have a 94 with a 5.3 , 4L60E. with ac and all my guages work.
The truck is still in progress. As I thin out the wires I have cut, I will remove more. I'll show when all is done.
@@laurencevillegarage Thanks for the follow-up.
Good videos.
Big difference in wiring set up between 88-94 than 94-98.
I incorporare harnesses on 95-98. Keep oem ac , oil pressure, abs and been working on keeping purge system. (EVAP) .
Learned a few things from you.
Like they say there are a million ways to skin a cat.
Keep up the good work and videos . Thanks for keeping the OBS's alive.
How is this working for you so far,? I plan on using the pancake style compressor.
I began with a R-4 (pancake) style compressor and I went through a couple of them. I finally switched to a Sanden style and had no more issues. I have seen many others with no apparent issues with them. If you have the space and already have one, go for it. If your swap is spatially challenged, then the Sanden may be a better fit (literally).
Did you use the same wire method on the R-4? Have you had any issues with the wire method since you changed to the sanden style? If need be, I may be able to go with sanden if they make a bracket to mount up top instead of the bottom.
@@kabarrion had to wire it a bit differently. The sanden was a single wire unit and the R4 is not. Simple enough, just use a different relay and just need a trigger wire. And yes, I used a bracket that can be used to mount the sanden compressor in place of the R4 from dirty dingo. Sadly, I sold the truck at that time to a friend. I provided the parts, but he had to do the switch.
Then 1 fan turns on when a/c or both?? Then both at temperature?
Fans are set up to go off at 185 and 195 degrees without a/c use. When a/c is activated, the low speed fan is automatically triggered to start.
@@laurencevillegarage @ then low fan its on as long as the a/c its on?
@@gerardolopez5875 yes, that’s correct.
On the fan relays, what wires go where?
For the regular twin electric fans, check out my video: 1988-98 Chevy OBS C/K Truck LS Swap Cooling Fan Fix. This shows how the dual fans are wired up. The a/c fan relay is wired differently.
@@laurencevillegarage i guess I worded it wrong. I meant to ask what a/c related wires are connected to what part of the fan relays? Like to what number on the relay? Just trying to figure out how to wire my a/c. We don’t really have too many a/c specific shops here in Colorado. I’ve had my swap almost 2 years. I’m running the dirty dingo street rod compressor kit. It’s a 1 wire. (Sd7b10)
How cold does your air at the vent?
I've never put a thermometer on the vent, but it's cold.
What happens if you have a clutch fan?
If you have an engine driven clutch fan then you would not have electric fans or a relay. You would just have a single relay for the a/c compressor. The engine driven fan would do all the work. Depending on where you live and how you use your vehicle may dictate how you cool your swap. If you are using a truck motor that never had an electric fan, you can use the mechanical fan...IF it fits in the space you have and is shrouded. You can do this first and see if it cools your swap well enough. If it does not, then add the electric fans. The electric fans give you more "precise" control of your cooling attempts. The mechanical fan, you just need to make sure the fan is in good functional order and hope it can keep things cool under all circumstances.
Agree, 👍no a/c ,,, useless,😩