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A/C conversion to Sanden compressor [message #129605]

Fri, 10 June 2011 18:37

Rick Williams

Messages: 256
Registered: July 2004

Karma: 0

Senior Member

I started a post a while back titled Sanden vs A6 compressor but I thought it might be better to start over.
I just completed the A6 to Sanden conversion on my 78 coach. I have learned much and spent a fair amount of time and money as well. Thanks to Ken Henderson and Bob Burkitt for their input.
I decided to reuse the existing three rubber hoses. New ones total to about $350.00. This means that the new compressor must have connections to fit the existing hoses. It is called a “pad” connection. There are several pad types for different make vehicles but they will not fit. Make sure it is a GM pad.
I purchased a Sanden compressor from Ebay. Sandens are made in Texas. Sanden “style” compressors are made in China. I bought a 7 piston compressor, model SD7H15. I know the Ken H is running a 5 piston compressor and it works fine. I went for more c.c.s. The A6 compressor is 207cc and the SD7H15 is 155cc. The rear head is a type GV. That designates it as a GM pad and puts the hose connection pad in the horizontal position. There is also a QC rear head that I think will work as well except that the compressor will have to be rotated 90 degrees. That is permissible according to Sanden. The rear head is easily changed on these compressors. So if you find a good deal on one with the wrong head, it can be changed for about $50.00. Make sure you get a new gasket. It is embossed steel. This rear head information is for only the 700 series (7 piston) compressors. The rear heads are not interchangable between the 7 piston and 5 piston compressors. You will have to research to find the correct rear head number for the 5 piston series. The SD7H15 Sanden comes with 9 oz of PAG 80cts oil and our system uses about 10.5 so I added a little extra PAG 100 cts. 80 cts is not common. The compressor mounted exactly as Ken described in the post mentioned earlier and required no shimming.
I bought a $30.00 quart of approved flushing solvent and flushed the entire system including the three hoses once it was in pieces. The hoses looked good for what that is worth. I took apart every connection that had o rings and replaced them. To do this, you must remove the front of the air box. The expansion valve is in there so there are connections with o rings. It is not especially hard but it is time consuming. It is best if you remove the heater hoses going to the heater core. At least it is on my 78. It was a good time to flush the coolant. And if you do not have the manual shutoff valve to the heater core, it is a good time to put that in. The coolant overflow tank comes out, the windshield solvent tank comes out and a bunch of screws around the perimeter. I took out the grill, the wheel well liner and disconnected the batteries first.
I did not flush the expansion valve and I did not replace it. New ones are not that expensive but they are made in china. I did have to go to several stores to find the correct size o ring for the expansion valve capillary tube. Auto Value ordered a package of 10 to sell me one at $.60. Part number STD24604
I did not remove the evaporator or the condenser. I poured solvent into them and used shop air to blow opposite the refrigerant flow. Oil came out with the solvent and air and was fairly clean. I did that several times until I could not see oil. I should mention that I did not have a compressor failure that put debris into the system. Flushing for that could take much more solvent. The remaining o-rings are very common. There were three different sizes in addition to the capillary tube of the expansion valve. I also replaced the receiver – dehydrator after all other connections were complete. The receivers come pressurized so as to not absorb moisture, so install it at the end so it is not open to the air any longer than necessary.
I vacuumed the system for a couple of hours and left it over night. With no leaks detected, I charged the system with Duracool as per Emery Stora’s instructions. It took somewhere between 3 and 4 cans (6 oz cans). The low pressure is at 20psi and the high side is 160psi. It appears to be cooling well but I have not had a chance to really try it out yet. It was 95 degrees here on Tuesday and only 55 on Wednesday when I completed the project. So my 15-minute ride as part of the charging procedure did not require much cooling. I will test it more later and report back with results.
Cost
Compressor $200.00
Receiver- Dehydrator $20.00
Flush $32.00
Duracool $25.00
O rings and oil $10.00

Rick Williams
Bliss, Michigan
1978 Eleganza II