jonathan_ed3

iTrader: (4)

Never occurred to me this would be a problem.

The BMW LS1 swap guys use LS1 compressors with their original expansion valves. The 240sx guys use LS1 compressors with their original expansion valves. The RX7 swap guys are doing it too.

What's the secret to making this work? It's not working for me.

https://ls1tech.com/forums/conversio...ble-fixed.html

I'm having the exact same problem the-jag-guy had in this old thread. See post #10 in the above link.

https://ls1tech.com/forums/conversio...ion-valve.html

In this thread the OP is referencing a problem related to the expansion valve too. See post #10. I've reached out to him, but I couldn't determine through searching if he ever resolved his issue and how he did it.

I already replaced the expansion valve and compressor (thinking those were problematic). In fact, at this point, everything in the entire AC is brand new. But it just won't work.

I've been told that it WON'T work (combining partial aspects of expansion valve system with orifice tube systems. But why does it work for the BMW, Mazda, Nissan guys? They're using expansion valves.

This is what the car is doing:

ls1nova71

iTrader: (4)

[QUOTE=jonathan_ed3;19552428] But why does it work for the BMW, Mazda, Nissan guys? They're using expansion valves.

QUOTE]

Have you ever personally seen it work on these cars? My guess is they have it "kind of" working. The LS1 compressor is a variable compressor and just doesn't work as well as a fixed one unless its run the way it was designed to. I tried it with a Vintage Air unit years ago and never was able to get it to work as well as it would have if I had used the right compressor.

jonathan_ed3

iTrader: (4)

I considered that

but theres dozens of swap guys across various make/model platforms that claim their setup works and works GOOD.

One of those is the owner of the e30ls1 swap kit - https://e30ls1.wordpress.com/

I doubt he'd be lying about it working well considering he's selling the swap kits and providing guidance on the ac situation for those cars.

Also please see FD RX7 how-to that several dozens have replicated and bought.

http://www.norotors.com/index.php?topic=23657.0

Its entirely possible that these cars are all working at reduced capacity. But they ARE working. Probably like an r12 to r134 coversion. It may never be perfect, but 99% of the time it's probably good enough.

Ive read that the variable compressor might operate somewhere at 75% efficiency when swapped.

At this point I'd be perfectly happy with that.

bczee

iTrader: (12)

I too would like to know how to get this to work. For years I have run the LS1 compressor and the original 71 Chevelle setup. It work for the most part as long as I was moving. But in slow traffic, the output would start to warm up. Never was able to get below 50 degree.

Last year I switch to a Old Air POA updated Expansion valve. The results was worse output. I was planning to now upgrade the Condenser in hope it would improve performance. If that doesn't work I would plan to Mod the compressor to fixed output.

Following this one for sure !
BC

jonathan_ed3

iTrader: (4)

It's think it's definitely possible. I just don't know how or why some are successful and others aren't.

If read over this thread you'll see the owner of the BMW E30 LS1 swap kit (garretvs) speak about how his ac system is ICE COLD.

https://www.bimmerforums.com/forum/showthread.php?723277-Need-help-on-A-C-with-LS1-E36-swap

I've also been communicating with Jeremiah at Rigid Racing for a few years. He too has verified working ac in his swap - a Nissan 240sx

http://www.rigidracing.com/2013/09/02/air-conditioning-in-a-240sx-with-an-ls1-swap-the-complete-post/

I also just confirmed with Andrew at Jaguarspecialties.com that it's possible. He said he's running at least 4 cars with LS1 ac swaps and expansion valves. I don't know what the issue was in his original post that I referenced but he did confirm it DOES WORK.

mutty

There is no compression taking place. Low side pressure [suction pressure] equalizing with the high side pressure [discharge pressure] shows that. You may want to check if your compressor is actually good.

69 Ghost

I've run both and have not seen much of a difference. Here are some things that you need to know:
1. Variable compressors do not cycle. They are made to run continuously. They do that by having a slightly higher low side than a fixed compressor is ment to run. For instance with my old vintage air with a fixed compressor was about 20-22 on the low side and a variable was 29-32 at idle.
2. For variable compressors you have to be careful about not over or under filling system. If you do it will not cool properly. They seem to be very sensitive to this. When I filled mine I went by the low pressure charts for the car. You then need to watch the high side to get that up while trying to keep the low side low. I ended up with about 38-42 psi on the low side for about a 90 degree day.
2. Vintage air states that a variable compressor is not ment to work with an expansion valve. They say that the valve and compressor with both try to control the system and it will burn up after about a year. I have a bit of a problem with this in that systems use either an orifice tube or a valve to do the same thing. I have not found this to be true I'm still on my original variable compressor that was run on a vintage system and now on a factory unit. Also note that variables are made to run continuously as stated in 1. One thing is that I have not seen a variable compressor from the factory using a TXV valve.
3. Pressure sensors control 2 things in GM cars. They control the secondary or high electrical fan and turn off the compressor if the pressure gets to high. Most people think that the pressure sensor is only for variable compressors. I used to think the same until I found some vehicles with them using fixed compressors and electric fans. Note that if a pressure sensor is eliminated or added depending on the OS you may need to modify P0530. If the system is looking for the sensor and it does not find it the compressor will turn off. This is a very common mistake as it does not turn on the mil and people miss it entirely. If you really don't want to run a sensor with electric fans the low fan will still work with a high pressure switch but you will not get a high fan from the ac only low.
4. Any Red-Blue or Blue-Green PCM can be programmed to work with any combination. There is one issue with some of the newer Blue-Green pcms in that some do not appear to have the AC request built in to the system. If you run into this it is best to source out a Express van PCM. Programming involves a few things. First is the compressor type. If you select a fixed compressor you need the low pressure switch to the ground wire like a truck wiring diagram. If you don't it will not turn on. If you remove or add a pressure sensor you need to program the system in the diagnostics to either look for it or turn it off. The second part is the electric fans. My recommendation is if you are going this route to program and wire it like a Camaro for low and high speed operation. Last part is HP tuners and Tunercat has the compressor type but EFI does not.
5. Low pressure switches are only used with fixed compressors and orifice tubes. TXV valves use an equivalent to turn the compressor on and off.

For those of you running older cars note that the older condensers are supposed to not be sized properly for 134. If you look at any AC website they recommend a new one that is built for a 134 system. A good source for a factory unit is a 96-04 S10 unit. They can be had for about $60 new. The S10's also used both fixed and variable compressors. I used S10 parts to build a hybrid system using a newer evaporator that uses an orifice tube system with a variable. S10 parts included the condenser, accumulator, and hard line with a built in pressure sensor port. For a fixed system you use the fixed accumulator which has a low pressure port. For those of you running older cars I would ditch the POA valve and go with orifice tube system. I did this for my car by using a 77-79 Nova evaporator that fit right into the factory box. Anybody running older Chevy's can do the same with similar cars.

Below are some vehicles to look up wiring, etc.

TXV valve cars. V6 Camaros and Cadilliac CTSV's
Variable Compressors S10 4 cylinders, Camaros, Vettes, GTO's
Fixed Compressors with pressure sensors 06 Tahoes

Note trucks and vans used fixed compressors without a pressure sensor instead they used a high pressure switch because they do not have electric fans.

jonathan_ed3

iTrader: (4)

thats the same thing we originally thought. Or that the expansion valve was stuck open (which is rare).

We are on the second compressor. First one was a brand new delco and second is a brand new 4 seasons (Chinese).

Also on the second expansion valve. First one factory Honda that worked perfectly before the swap and now a brand new aftermarket one.

But at this point im relatively sure the compressor is working. If it wasn't pumping we wouldn't see the pressures drop?

jonathan_ed3

iTrader: (4)

That's the way I understand it also. The only reason they will ever cycle or cut off is if there's a pressure problem, regulated at the high side pressure sensor. Which is what I'm seeing happen. The high side is dropping below 35psi and the pressure sensor is telling the PCM to shut it down.

That's the main problem with a conversion, I guess.

You really don't know how much to fill with.

In my case we've tried anything from 1lb to 2lbs with literally no change whatsoever in the pressures. We can get the low side pressure to get a little high but the high side never goes over 50.


I've continuously read the same thing over and over. Although not ideal, it can and does work. Jeremiah at Rigid Racing has had his going for over 3 years using an expansion valve with the LS1 VD compressor. I'm sure some of the FD RX7 guys have been going much much longer than that, as the swap has been popular in that chassis for a decade ++


I wish I could get my pressure high enough to see the high pressure cut off. I Can't even pump over 50

We're using a red/blue 411 PCM with an 01 F body file loaded into it. Do you know what the programing should be called for the VD compressor? Is it analog? I read something a while ago about what the proper file should be loaded as but I cannot remember what it said and I misplaced my notes I took on it. I think it's supposed to be analog serial??? Does that sound right?



Very good info here.

Unfortunately, I have to use my Honda evap core and expansion valve. I could theoretically (if I had to) put an orifice tube in the system, but wouldn't this necessistate getting rid of the expansion valve? If so I'd have no easy way to get rid of the expansion valve block and connect directly to the evaporator core. I'd have to get something custom welded up.

And at this point, I'm not sure that's even necessary. As posted earlier in this thread, DOZENS of import guys are making expansion valve setups work with the VD compressors, and not using orifice tubes or accumulators. The question is why does it work for them but not for me? I don't know enough to be able to answer that.

Bottom line I'm not going to hack up my dash to try to fit anything else, especially from a GM car. The Honda evap and expansion valve barely fit, although they are factory R134a as is the condenser. I seriously doubt there's any efficiency limitations between those components that would negatively impact this current hybrid system. If it was originally an R12 car, then yes...I've been down that road and intimately understand the need to switch. But this is all factory R134 stuff.


One of the a/c techs at work suggested that maybe the compressor hasn't pumped enough to actually fill/pressurize the system and/or is still grossly underfilled. It's literally only pumped for about 1 second at a time.

What do you think about me completely bypassing the GM PCM and pressure sensor and sending 12v straight to the clutch for a few seconds and see what the pressures do? At this point I think it might be worth the risk.

If the high side pressure actually rises, does that give credence to the idea that maybe I'm just still way low on refrigerant?

or perhaps there's a restriction between the compressor discharge and the service fitting. But I don't see how since everything is brand new. We're going to test high side pressure closer to the compressor today once the rain stops.

There's gotta be a way to make this work. It's got to be something stupid or that I'm overlooking, but I've asked 3 Master Tech's, a Master Tech TRAINER, and all my car buddies and we don't get it. It should be working.

gofastwclass

iTrader: (2)

I just posted this in another thread... summer is getting closer.
Within HP Tuners there are six options for this PCM style. The factory F-Body and Y-Body (2002 V8 Camaro and Corvette) is Analog. For the 2002 Silverado the option needs to be Analog Cycling.

jonathan_ed3

iTrader: (4)

Gofastwclass, thanks for the info .

we tested pressure again today but this time we tested on the high side line between the drier and the condenser.

We also manually powered the ac clutch, bypassing the pcm entirely so it didn't override anything via the pressure sensor.

Exactly the same results. No matter how long we let it run, the high side pressure never materialized like it should be.

We did however notice that the schrader valve at this location started to leak after we pulled off our gauges. Although to be fair we are fairly certain it was not leaking beforehand, as our pag oil is UV tinted and there was no trace beforehand. It's leaking pretty well now though.

Ordered another high side service port and we'll splice this in between the compressor discharge and the condenser.

We'll evacuate then fix the one leaking port, fill and test again.

im hoping the pressure is good there, as then I know I've got a condenser problem (even though it's brand new)

If the pressures look the same there yet again does that mean?? bad compressor? Or low on charge?

jonathan_ed3

iTrader: (4)

so we evacuated the system, blew out every hose/hardline. Confirmed no blockages in any lines or in condenser etc.

Then we tested the manifold gauge set on my daily driver to rule out any gauge issues. They work, and they're accurate (was especially interested in the high side gauge).

Reinstalled everything and vacuumed, then recharged starting at 1 lb and went up to 21 ounces (the original Honda capacity). Basically stopped at 21 ounces because nothing was really changing pressure wise and we decided we're probably just wasting refrigerant (and we've wasted a LOT already through all of this) by continuing to fill.

We manually powered the a/c clutch to rule out any PCM overrides.

21 ounces in system. Clutch engaged FULL TIME, (manually jumped to bypass any PCM overrides), 80 degrees ambient, low side pressure continuously swung from 25-33PSI, and high side did EXACTLY THE SAME THING. 25-33PSI swing, together, in unison. It was about 75 degrees at the time.

Both gauges just kept swinging back and forth 25-33, 25-33, 25-33. With the clutch engaged full time! This correlates exactly with the pressure swing from the very beginning. The original youtube video has the exact same pressure swing when the clutch engages, although at the time we were letting the PCM control the clutch vs having it run full time now.


Suction line didn't get cold, discharge line didn't get hot, or even remotely warm.

So one of the running theories among the group of people helping try to figure this out is that perhaps the nozzle/orifice point inside the expansion valve is a little too big, therefore not allowing pressure to build. Okay, I can buy that. That would explain why the notion exists that these Camaro compressors don't work with expansion valves, even though dozens of Nissan 240sx, 240z, Mazda RX7 and various other hot rodders have made an LS1 compressor work with an expansion valve. It might not be "perfect", but it does work well enough.

However, in this case, I don't think the expansion valve is the problem...

Earlier today before pulling the system apart I completely pinched off the high side line with a vice grip wrapped in a rag and couldn't get the high side pressure to rise much more than ambient. And at the time the system had a higher charge than it did during this last test. Although not 100% scientific/accurate or possibly even safe, I know for a fact I pinched that line pretty darn good. At this point I don't care about the longevity of that line, I can always remake it if need be. Shouldn't high side pressure have skyrocketed as I continued to let the clutch run?

At this point I have to lean to defective compressor. For the SECOND time, from a DIFFERENT manufacturer. I cant fathom this as a possibility, but nothing else makes sense. RIDICULOUSLY low charge??? IDK.

It could be argued that the refrigerant charge could be low, but the fact that the suction and discharge are doing the exact same thing, in unison, points more towards a compressor issue than anything else. I'm just a novice, but nothing else makes sense.

ls1nova71

iTrader: (4)

I'm no expert by far, but it does sound like the compressor isn't working, although I would think that two compressors doing the exact same thing would be rare, but I guess not unheard of? just throwing this out there, and I'm sure you've already thought about it, but is there any way to mount the factory compressor from your car to the LS engine? I did that with a ford conversion when I didn't want to break the lines open.

mytmouz

iTrader: (2)

An ls truck compressor is fixed displacement. It might be worth trying....

Michael Yount

iTrader: (1)

If you're having to replace compressors anyway -- can't you put a Sanden fixed displacement in it? Or is there a fitment issue? I run a 508 in the low mount using an Alan Groves accessory kit. WAY DOWN there in the bottom of bay where you can't even see it.

69 Ghost

I know you said you bypassed the ac request but it sounds to me like your compressor is not turning on properly. My first question is are you running a pressure sensor because the system is looking for one if it does not find one it will turn the compressor on for 1 second then off. I would make sure the clutch is engaging full time given everything else you have stated. If not you need to try to turn off the sensor circuit p0530 then try again. If you don't have a datalogging setup you need to get something. You can log and check with it. Note that if the sensor is bad or it does not see it it will not turn on the light.

I modified 3. to clarify this in my post above.

Q8y_drifter

Subbed.

OLDSMAN

The problem here could be a plugged expansion valve or the sensing bulb on the valve lost it's charge. New parts can be defective. Intuitively, that is usually not the first thing thought of in a case like this.

mutty

The ac compressor functions just the same as the car engine. No compression>no power=no compression>no refrigeration. Plugged expansion valve or txv is going to cause excessive high side pressures[discharge pressure] which will show on the gauge. Even though you bypassed the circuit and applied power directly to the compressor, that compressor is not pumping anything.

jonathan_ed3

iTrader: (4)

Guys, forgot I never updated this thread. We've had the ac working great for a few months now.

Turns out the problem all along was the GM a/c pressure sensor fitting that we had made. The guy I had made it basically soldered the entire T fitting shut!!!

So it was acting as a restriction between the expansion valve and the compressor, but making the gauges act in such a way that it didn't present itself as an actual restriction. Basically the pressures were equalizing through the expansion valve/evap and acting in unison and along the way tricking us into thinking compressor(s) were bad.

Somehow we overlooked it each and every time we were messing with it. I never really thought to investigate the GM pressure sensor fitting itself because it was brand new and installed in a brand new line!!

Got a new fitting made, crimped it into a new line, and we've been golden since.

Funny how it's always the stupidest things that stump you.