I've been gearing up to replace the seized compressor in my 93 240. I thought it was going to be a simple R&R, but the more I get into the job, the more questions pop up. So:

After some research, I've decided to exchange the NLA Seiko-Seiki SS-121DS5 for a more available (and hopefully more robust) Sanden SD7H15.

1/ From web searching, it appears that my original SS-121DS5 has a thermal cut-out and a High Pressure Relief Valve (HPRV). I cannot find a Sanden with a thermal cutout, but I think can get one with or without a HPRV. Should I get one with he HPRV head or not? Also, should I find a way to install a thermal cutout?

2/ The original SS-121DS5 has a 122mm clutch. Since I cannot find the displacement/rev for this compressor I am not certain whether to get the Sanden with a 125mm or 132mm clutch. I have a feeling that the Seiko might have less displacement than the Sanden and needs to be overdriven to make up for it, hence the smaller diameter clutch. Can anyone recommend which clutch to go with?

My 93 cooled well enough, but just well enough; I do not want to do anything bone-headed that changes that.

Also, if anyone has done this swap, I would love to hear about it.

Thanks, one and all,
Rich (near Pittsburgh)

hello rich,
try this site: http://www.sanden.com/

if you do a search for your 93, it states their compressor 4464, a 132 mm clutch.

for your choice of sanden compressor, sd7h15, crosses to 4664
http://store.sanden.com/index.php/4664.html

this site includes links to 1. a drawing of this compressor dimensions and 2. to your service guide. the dimension link doesn't expand to see, so you will need to click on the x in the right side to download the pdf file.

but here's the same service guide but as a pdf online:
http://www.sanden.com/productlibrary/manuals/SD_Service_Guide_Rev_2.pdf

if you look on page 8 of the service guide word document, it mentions torque values for a thermal protector switch and the hprv, among installations instructions, oil specs, etc.

a) note that these sanden compressors use pag oil, not ester. you will have to back flush your system to clean out the ester oil. i used my own home air compressor with an a/c flush kit.

b) if you go this far, best to use new o-rings for as many a/c pipe connections you can get to, and replace the orifice tube. i took apart the tubes and flushed everything.

c) you might need a different size a/c belt with a larger clutch.


i bought the sanden 4434 (SD7H15SD) with the port fitting 4866-6340 (sanden calls these compressors flex, you can attached different port sizes for different applications). i wanted a more heavy duty compressor, but this port fitting does not exactly line up with the low and high pressure fittings, so i had to bend them a little bit, carefully of course.

regards,
byron golden
86 245
92 245
94 940

Hi,

I think you are asking, should I go large or not!

If the new Sanden does have more displacement, I suggest you go with the larger.
7mm really isn't that much of a difference.

It will give the engine a little more torque advantage over the stopped compressor when the clutch reengages.
The engine will turn more than the compressor will if is larger than the crankshaft pulley.
Any displacement difference will make up for the the lesser speed.

This is good under any residual head pressure, especially on hot traffic days, if the system has not had the chance to equalized somewhat between cycles.

Since this system does not use a TXV but an orifice tube expansion device, you are kinda stuck with its performance with that evaporator. No playing with superheat adjustments to control amount of flood percentage.

The best thing is to make sure the condenser fan is working as it should and the fins on both the condenser and radiator are clear of debris.
You want to get as much of the hot vapor gas to condense to a hot liquid and then lose some of that heat as well!

A steady liquid flow through the device is what is wanted. An orifice device works at a steady pressure and quantity of "designed in perimeter conditions" world wide!
The liquid pound and ounce charge is more crucial without excessive reserve.
Bottom line is, the whole system, "Is far cheaper to make!"
Plus they get away with no thermostat, which is another expense.

The flow amount is like having a bucket of water steadying pouring on a fire instead of several glasses slung (sprayed) by hand per minute!

If done correctly and if the compressor is you get is up to the capacity of the two coils, it should still do a very decent job!

Just don't expect ice cubes or snow flakes to be dispensed!

Phil