gm ac compressor to sanden swap?

[1774btcrew]

Originally Posted by ERBSIX

So are there any direct bolt-in replacements options for compressors?

I have a 78 silverado with the factory compressor and it really bogs down the truck.

I'm betting its going to die in the near future (very old).

I would love to find something I can just unbolt the old one and bolt in a new one...?

Is your truck a small block or big block?

[El Campo]

Oh wow, I will be building my own then! They do look good though

[davidh]

Okay update here. We put this on my 95 3/4 ton TBI but we're having problems. 2lbs refrigerant, 200psi high, 34 low side. 40F. The problem is that when you start the ac you can hear the pressure build up and then it blows the high side hose?? I had new hoses made. Mechanic put back on and when he hears the compressor make the similar sound(as when hoses blow) he turns the ac off, waits a moment or two then turns back on and its ok. The ac system is all stock other than this new sandon compressor. Mechanic thinks this new compressor puts out more psi and we've lost the high psi shut off the R4 compressor... Would a variable orfice work>>?? I'm at a loss here.

[Firebirdjones]

Originally Posted by Ford Assassin

Digging up an old thread....

Hey guys, are you running the rest of the GM designed A/C parts? Is the system running as well as stock? Better/worse?

I ask because I bought a Sanden 508 and Kwik Performance bracket for my '86 K5.


I went to a local A/C shop with the truck and had custom hoses made. As I was paying for the hoses the guy decides to say, "You know that Sanden 508 isn't big enough for the factory GM evap, right?". I wasn't too happy he is telling me this after I just spent $100+ on custom hoses.

So I am curious to hear what you Sanden conversion guys have to say.

Thanks!!

I've done the same swap and heard the same thing from a friend and local AC shop owner here. These little Sandens don't move the same amounts of freon as the larger compressors did. However in my case I didn't have much choice as I was doing an LS swap at the same time.
I did this on a 72 blazer so I used a POA eliminator kit to cycle the compressor. Since it still uses a thermostat of sorts to switch it on and off,,,,it's rather slow as a result. I needed to have custom hoses made as well. The biggest problem with my system is using 134 freon with the old R12 condensor, as it doesn't cool the freon efficiently, and in turn makes the high side line pressures higher than they should be. This limited the amount of freon we could put in the system to keep things at a safe level.
The only saving grace I have is that I installed a dual electric fan setup with the swap and have them wired to trigger on with the AC switch. This way they are pulling air when sitting still and it helps to cool the condensor and keep those high side pressures reasonable.
Ultimately I need a 134 specific condensor that cools better, but that would require more custom lines to be made, a different dryer setup with orifice tube etc.....about another $600. So I elect to leave it as is.

Works okay in the AZ heat, keeps the family comfortable,,,not ice cold, but comfortable. So for now it's doing it's job well enough.

You have an advantage with your 86 since that should be a dryer/orifice setup. Works better than the old POA swap I did.

Actually yours should be similar to my 79 pickup which I converted to 134. I still run the original (HUGE) compressor on this truck and love it. I'm told from the local shop that nothing pumps like these old compressors do. Unfortunately everyone is all about engine drag and mpg so they tend to toss them. It's an oldy but a goody Even using the old R12 condensor with 134 freon conversion this thing will run you out of the truck. Family complains all the time that it's too cold

[Firebirdjones]

Originally Posted by davidh

Okay update here. We put this on my 95 3/4 ton TBI but we're having problems. 2lbs refrigerant, 200psi high, 34 low side. 40F. The problem is that when you start the ac you can hear the pressure build up and then it blows the high side hose?? I had new hoses made. Mechanic put back on and when he hears the compressor make the similar sound(as when hoses blow) he turns the ac off, waits a moment or two then turns back on and its ok. The ac system is all stock other than this new sandon compressor. Mechanic thinks this new compressor puts out more psi and we've lost the high psi shut off the R4 compressor... Would a variable orfice work>>?? I'm at a loss here.

You're on the right track. When I did the conversion on my 72 (read above) I ran into the same issues with high side line pressures too high. We had to be carefull of the amount of freon we installed (2 1/2 lbs. max) in a system that should have taken 3-3 1/2 lbs.
The issue in my case was the condensor getting hot (old R12 condensor not cooling the 134 freon well enough). I run a sanden compressor on this setup.

On the flip side, I did a 134 conversion on my 79 that uses the factory (R6??) compressor. (the big one) and it blows ice cold.

Those sandens may take less HP to turn and give back some MPG, but according to the AC shop here, they don't work as well unless you convert the entire system to accomodate it = $$$$ because of this I prefer to keep the original compressor on my 79.

[davidh]

Originally Posted by Firebirdjones

You're on the right track. When I did the conversion on my 72 (read above) I ran into the same issues with high side line pressures too high. We had to be carefull of the amount of freon we installed (2 1/2 lbs. max) in a system that should have taken 3-3 1/2 lbs.
The issue in my case was the condensor getting hot (old R12 condensor not cooling the 134 freon well enough). I run a sanden compressor on this setup.

On the flip side, I did a 134 conversion on my 79 that uses the factory (R6??) compressor. (the big one) and it blows ice cold.

Those sandens may take less HP to turn and give back some MPG, but according to the AC shop here, they don't work as well unless you convert the entire system to accomodate it = $$$$ because of this I prefer to keep the original compressor on my 79.

my truck is a 95 so its R134 and its the bigger 709(?) compressor. It's only got 2lbs of coolant in it.

[Firebirdjones]

Sorry bud, thought you were speaking of a conversion done.

[davidh]

do you think this might be whats needed?? binary switch on high pressure side?? Since this was lost when taking the R4 off
http://www.nostalgicairparts.com/pop...=769&subid=449

[Firebirdjones]

You don't have a cycle switch?

[Ford Assassin]

There should be a cycle High/Low switch located on the acumulator itself.

Plus, I do think the variable orifice tube will help. They help prevent pressure spikes and help with compressor life ALOT. For $20 I'd say its worth a shot.
Posted via Mobile Device

[davidh]

should the variable orifice be available at most parts stores? I just left the shop and that's what they think will help.

[Ford Assassin]

Originally Posted by davidh

should the variable orifice be available at most parts stores? I just left the shop and that's what they think will help.

I bought mine at O'Reilly's. It was a regular stocked item. I think AutoZone stocks them as well.
Posted via Mobile Device

[davidh]

I drove the truck around last night and the AC with the 709 sandon works better than before. The compressor has a different sound than the r4. It will run you out of there. My truck is a single cab but I had on fan 1 max ac off and was cool. I think on the highway you could put it on "meatlocker mode".
I just have to bleed off the pressure at initial start up. If iI turn off and run into store and come back I DO NOT have to do this again just after sitting a while.

Anything look out of place? I hope the variable orifice tube will do it.

[tucsonjwt]

Off the topic a bit, but there is an aftermarket seller for a modified A6 for older GM vehicles. I don't know how they work but they seem like a good concept. I have asked local A/C shops about a Sanden replacement but they would never do it - saying the capacity is not enough for large GM vehicles. They always recommend OEM.

http://www.s6compressor.com/

[Ford Assassin]

Originally Posted by tucsonjwt

Off the topic a bit, but there is an aftermarket seller for a modified A6 for older GM vehicles. I don't know how they work but they seem like a good concept. I have asked local A/C shops about a Sanden replacement but they would never do it - saying the capacity is not enough for large GM vehicles. They always recommend OEM.

http://www.s6compressor.com/

From personal experience, either the 'Pro' AC guys are scared or just don't know what thry are talking about. I was told the samething and my 'little' Sanden (chinese knockoff) 508 kicks ass.
Posted via Mobile Device

[davidh]

Originally Posted by tucsonjwt

Off the topic a bit, but there is an aftermarket seller for a modified A6 for older GM vehicles. I don't know how they work but they seem like a good concept. I have asked local A/C shops about a Sanden replacement but they would never do it - saying the capacity is not enough for large GM vehicles. They always recommend OEM.

http://www.s6compressor.com/

my ac works better than before once this bug is worked out it will be great