Sanden AC compressor install (almost)

[Dan_Austin]

After the 3rd R4 'pancake' compress failure in 18 months (all professionally installed), I decided to try one of the Sanden conversion kits. It came with a head on the compressor compatible with our lines, which was one of my concerns. The install was a bit fiddly, but mostly of the sort that a 3rd hand would have solved.

That was until after getting the compressor in, lines routed and belt installed did I notice the compressor intrudes on the intercooler space. Not by much but enough that it isn't going back together soon. I looks like I might be able to notch the tank to clear the compressor. I have reached out to a couple friends who I think can TIG weld the tank and will be waiting on them before I start cutting.

 

[DaveP's Ghost]

I live in SoCal, I use the A/C every time I drive it. The original compressor on my 93 was replaced in 2012 after 20 years of service because it was leaking at the shell. The replacement is still functioning just fine. Same with my other 100RT compressors on other GM vehicles. (It hasn't been called the "R4" for a long time.)

The Sanden 505 is a 8.4 cubic inch compressor. The 100RT is 10 cubic inches. You're giving up cooling capacity (particularly at idle speeds) with the smaller displacement.

I would have figured out why I'm having trouble with the stock compressors, not go through the hassle of changing the design.

 

[DaveP's Ghost]

Only a GUESS: You aren't using PAG oil in your retrofit R134 system, are you? PAG and the residual mineral oil used with R12 make a mess when mixed. The correct oil for a 134 retrofit is POE/Ester. Perhaps your "professional" installer doesn't know this?

 

[Dan_Austin]

The professional is my brother's shop and he harps on doing it right. That said the work was done by a tech that is long gone and after the fact we figured out that he was taking short cuts. I found a black crushed and torn O-ring on a line that should have been taken off to to the job right. So wrong type and damaged. The orifice valve was filled with black sludge, and I doubt that happened in the less than a year the system worked. Now I am installing this kit myself. I had done a few and have the tools, gauge set and vacuum pump. This way when it goes south, I know exactly who is at fault.

The kit came with a Sanden SD7H15, which only gives up about .5 of a cubic inch, and is a better compressor design. I took the upper intercooler out and have come up with these options-

1. Cut off the intake oval at the weld and shift if forward 1"
2. Notch the front left water tank, about 1" up from the bottom and 2" in from the drivers side. It will impact water flow, but not too much
3. Combination of 1 & 2
4. Buy a Mishimoto dual pass and modify it (too mush $$$)
5. Buy a core and work with my friend to weld up something that fits. (Will take too long)
6. Buy a TB mounted air filter and drive without boost until I can come up with another option, but at least have AC here in the desert

In any case the A/C swap is done, so very unlikely I will be going back to the R4/RT100. It may well be that the lazy tech and a suspicion that who ever did the original R12 to R134a conversion did not do it right setting the stage for failure. It is also possible that I got two bad replacement RT100 in a row and at least some of the damage was from them failing. I guess I can think of this as an opportunity to come up with a better A2W design if I want to go with option 5...

 

[DaveP's Ghost]

The black sludge is of concern. Whatever is causing it could take out the Sanden as well. I'm surprised that an SD7 series fits lengthwise. All I've seen on Vintage Air installations is the 505. Little compressors give lousy results. I have a C4 ZR-1 that has a 10PA17 compressor because of packaging requirements, the 'regular' car has a 10PA20. There are other considerations, but the ZR-1 doesn't cool off as quickly as my 85 that has a RT100 and full size evaporator core. And neither cool down as quickly as the 88 I had that had a 10PA20.

 

[Poconojoe]

I don't see where you mention flushing out the system, after the compressor failures. Rockauto has a nice flush gun for around $35 and you can buy flush for around $10 a quart. I'd run 2 quarts of flush through it and then purge it out with nitrogen. I always power my flush gun with nitrogen so I don't get moisture is the system, from using compressed air. Dave is right about something contaminating, the system, those old compressors run 25 or 30 years, until the front seal leaks enough, that they run low on oil. I can't count the number of people I know, that just threw a can or 2 of R12 every cooling season and never worried about the oil dripping off the compressor

 

[Dan_Austin]

I flushed the evaporator, lines and condenser this time. It is standard procedure to do it at my brothers shop, but we don't know if the tech did it. Based on what I found I don't think so. The last R4 would 'growl' when it engaged. If I had torn the system apart before ordering the kit I might have risked one more pancake and made sure it was new. But I know from experience that if I start a project without all the expected parts on had, it is going to get 1/2 done and then be stuck waiting on parts that should be available locally, but are not.

Turns out I had the compressor clocked the wrong way, which I found before running it. After correcting that the intercooler almost fits. It still needs cutting and welding, but on a smaller scale.

 

[Asadmobeen]

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