Any recommended AC Compressor replacements?

[Andrew]

I’m running a universal parallel flow condenser on 4194. IIRC it was less than $100 back in 2016. It’s the same height as the stock condenser, but it’s about 3 inches shorter in length. I replaced an older vendor supplied tube and fin unit which never delivered decent vent temps. The parallel flow condenser delivers vent temps similar to the stock serpentine unit. (Low 40s with 134a). Thus, I wouldn’t recommend replacing an otherwise good stock unit with a universal parallel flow, but it’s a good option to replace a damaged / missing condenser and better than a tube and fin.

I can find the part number and supplier name if anyone wants it.

[FABombjoy]

I can find the part number and supplier name if anyone wants it.

...ahem *coughs conspicuously*

CNFP1226

[hippieman9]

Sanden model 6668. with a GM "Q" type Head.

[Ethan Rode]

Sanden 4708 is the one to get. There is a 5-cylinder Sanden compressor that works too, but the 7-cylinder runs smoother IMHO.

If you're not replacing the condenser with a parallel flow unit, you are wasting your time and money. Condenser efficiency has a huge impact on how the system will perform. Original is good for R-12, but sucks for R-134a.

You'll need to specify with your vendor that you want a "QC" head. There are a few different "Q" style heads with a pressure relief port that is in the way for our application. Be warned that many QC heads are now coming with a smaller port size for the discharge. The head will need to be removed, and the port enlarged on a drill press. I also shave down the heads on the top two headbolts to give the service ports more clearance.

Be sure to update your pressure switch for R134a, too, after thoroughly flushing the evaporator, replacing receiver/dryer and oriface tube.

[82DMC12]

Hey guys,

I'm gearing up to do a frame-off this fall and of course that means discharging my A/C. A few years ago I replaced every single A/C part and hose except the evaporator. It's been working pretty well but after 6 or 7 years I think I have a very slight leak somewhere. I'll probably have it discharged at a shop and then have them check for leaks before I disassemble so that I can address whatever the problem was while my frame is out.

I currently have a Sanden SD5H14. Is it really worth spending ~$215 to put the SD7H15 in instead? If so, I'll just go ahead and order the compressor so I can swap it out. I don't care about the money, but if it's only like 5% better then I won't bother.

Andy

[Ethan Rode]

Andy,

No discernible performance difference between the SD5 vs SD7 compressors in terms of vent temps provided the condenser was updated, in my experience. The biggest difference I noticed is the SD7 seems to suck less power on cut-in. I don't have any data other than butt dyno. If you have a genuine Sanden SD5, change the oil and keep running it as long as the orifice tube is clean.

Hey guys,

I'm gearing up to do a frame-off this fall and of course that means discharging my A/C. A few years ago I replaced every single A/C part and hose except the evaporator. It's been working pretty well but after 6 or 7 years I think I have a very slight leak somewhere. I'll probably have it discharged at a shop and then have them check for leaks before I disassemble so that I can address whatever the problem was while my frame is out.

I currently have a Sanden SD5H14. Is it really worth spending ~$215 to put the SD7H15 in instead? If so, I'll just go ahead and order the compressor so I can swap it out. I don't care about the money, but if it's only like 5% better then I won't bother.

Andy

[82DMC12]

Andy,

No discernible performance difference between the SD5 vs SD7 compressors in terms of vent temps provided the condenser was updated, in my experience. The biggest difference I noticed is the SD7 seems to suck less power on cut-in. I don't have any data other than butt dyno. If you have a genuine Sanden SD5, change the oil and keep running it as long as the orifice tube is clean.

Thanks for the advice. I'll probably just keep the SD5 then.

By the way, when I open up the A/C system I will have to transfer my condenser, lines, dryer, etc to a different rolling chassis. Some connections will have to be made again which means the o-rings were exposed to the air. I'd prefer to change the o-rings rather than reuse them. They are already the green type. Do you know if these o-rings are metric or SAE? Would NAPA have them? I think I got everything as part of a kit from Hervey. Maybe if they aren't cut or scratched I can use them again.

[David T]

Thanks for the advice. I'll probably just keep the SD5 then.

By the way, when I open up the A/C system I will have to transfer my condenser, lines, dryer, etc to a different rolling chassis. Some connections will have to be made again which means the o-rings were exposed to the air. I'd prefer to change the o-rings rather than reuse them. They are already the green type. Do you know if these o-rings are metric or SAE? Would NAPA have them? I think I got everything as part of a kit from Hervey. Maybe if they aren't cut or scratched I can use them again.

Good practice is to replace the "O" rings but if they are not nicked up and flattened they can be reused. Wet them liberally with refrigerant oil before assembly. Any large auto store should have an assortment of "O" rings to pick from. If the leak is very small try using a sealer when you have the system recharged. All systems leak. There is a tolerance spec based on the length of the hoses, the more and longer the hoses, the more the system can leak. Barrier type hoses leak less then ordinary refrigerant hoses. A few ounces every other year is not worth trying to fix except with sealer. Exposing "O" rings to air is not what damages them, they take on a "set" and don't always reseal well once used.

[mark w]

I plan to flush my system and replace all the seals, orfice and the compressor with the SD7 unit.
I understand its prefilled. but I cant find info on what type, or how much is in there, and how much more oil I should add after, to the system.
anyone know?

[kings1527]

I plan to flush my system and replace all the seals, orfice and the compressor with the SD7 unit.
I understand its prefilled. but I cant find info on what type, or how much is in there, and how much more oil I should add after, to the system.
anyone know?

For a new condenser, evaporator, hoses, or accumulator, replace it with 2oz of oil for each component. Again, this is when it's either flushed or brand new. As for the compressor, if it's new from Sanden, it'll be filled with PAG which is compatible with r134a. If you're looking to use R12, you'll need to replace that PAG with mineral oil. To put the right about in the compressor, open the plug on the compressor and drain the prefilled oil into something you can measure with, like a Pyrex measuring glass. Then simply replace the same amount with mineral oil and now you can run a r134a compressor with R12. The only difference is the prefilled oil. Everything else is the same.