Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

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compressor were tough to get off and on (seemed to be too much bending
involved. Perhaps mine were not original Volvo.
Be very careful threading lines into the soft Aluminum threads on the compressor.
Go by hand as much as possible before using the wrenches.
The electrical connector for the new Seltec compressor was not the right size for
the old line.
I had to file the hole in the compressor wire holder that bolts into one the the
compressor mounts so it would fit.
The Seltec compressor did not have a drain so I was advised by Rusty (RPR) to
turn upside down and rotate to get fluid out of the inlet/outlet. Ester oil was added
to the receiver/dryer only per advise.
I'd consider ordering all new hoses if I did it again (hopefully I'll get by)
I do not know why the kit did not come with new seals for the whole system:
hopefully not needed?
[Tips from Lee Fox] RE: 740 AC conversion and variable orifice tube. I just got done converting
my wife's 1990 740GL from R-12 to R-134a and thought I would report on the process. Many
thanks to David Urban's most helpful web page describing the entire procedure. He gave me the
encouragement to try it myself and he saved me at least $100. I purchased the conversion kit
from Brentwood Volvo for about $50, but could not get one of the connections on the old
accumulator off, so had to buy the supplemental kit for pre-1988 models for an additional $28.
My system had leaked out all of the old R-12 from the original factory fill valve. The folks at the
dealer said that this was common and now install the supplemental kit whenever they do the
conversion. Following David's instructions, the changeover was easy, taking less than one
hour. I rented an AC vacuum pump and gauges for about $25 and bought three cans of R134a
plus some leak detector (I wanted to make sure I didn't have a leak elsewhere) and a charge
hose for about $30 from Auto Zone. You have to evacuate the system for about an hour and it
took about another hour to get it charged up. I had to jumper the low pressure switch to get the
compressor going to suck in the first can. When I returned the vacuum pump I had to wipe to
condensation from my glasses walking into the store - it was that cold inside the car! [Chris
Herbst] Consider adjusting the R12-calibrated pressure switch on the receiver-dryer to cycle off
around 20lbs. R12 is set higher.
Flushing Debris Out of System.
[Larry Carley, Underhood Servide, April 1999, ed.] When a compressor fails, it can throw
metallic debris into the system. Most of the junk ends up in the bottom of the condenser, but
some of it can also be blown back into the suction hose. Flushing the condenser, hoses and
evaporator with refrigerant or an approved solvent may remove most of the debris. One
aftermarket supplier's A/C flush solvent, "Dura 141," has seen successful acceptance by the
repair industry. It has a boiling point below 90 degrees Fahrenheit, so leaving residual solvent
doesn't appear to be a problem. However, modern parallel flow flat tube condensers cannot be