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

960 Procedure. [Editor] Your evaporator is far easier to remove than that in a 740 or 940.
Remove the battery negative and evacuate the air conditioning system. Remove the firewall
connections, including the metal plate and washer, for the pipes leading to the evaporator.
Remove the glove box and passenger kickpanel, then the plastic evaporator cover. Pull the
evaporator out. You may have to remove the air bag bolster (the large metal bar near the glove
box) if it is in the way of the evaporator.
Hose Replacement. [Tip from Rafael Riverol] When I retrofitted my 760T A/C from R12 to
R134, I put in all new Volvo parts from Swedish Engineering including new hoses. Soon, I found
the entire hose from the compressor to condenser glowing green with UV dye because R134
was leaking right through the body of the hose. Later, I found out that Volvo has information out
recommending use of barrier type hoses when retrofitting A/C to R134. It turns out, original
hoses will hold R134 only when saturated with mineral oil used with R12. New hoses or flushed
out old hoses (cleaned of mineral oil) will not hold R134 because its molecules are smaller than
those of R12. I had received and put in the car an original Volvo hose good only for R12. Be
sure to put in new barrier type hoses designed to hold R134 when retrofiting from R12.
Rebuilding Hoses. I've found that flexible ac lines typically start leaking at around 100k miles
and can be expensive to replace. I've located a repair service in Tucson that can fix your
existing line for around $50: mail them the old hose and they rebuild it . They seem to do good
work. Century Auto Air.
A/C Compressor Failure.
General Notes. [by Larry Carley, Import Car Magazine] The most common symptom of a
compressor failure (besides no cooling) is a seized compressor. It won’t turn when the magnetic
clutch engages, and you may hear squeals of protest from the drive belt. Or, the belt may have
already broken or been thrown off its pulleys. Loss of lubrication is unquestionably the most
common cause of compressor failure. This can happen when there’s a refrigerant leak
somewhere in the system that allows refrigerant and oil to escape. Typical leak points are
hoses, hose and pipe connections (O-rings and flange gaskets), the evaporator, condenser or
the compressor shaft seal. An electronic leak detector or dye should be used to find the leak so
it can be repaired. A restriction inside the A/C system can also starve the compressor for oil. Oil
circulates with the refrigerant, so if the orifice tube or expansion valve is blocked it may cause
the compressor to run dry and seize. Even if a compressor is still turning, it may have to be
replaced if it’s leaking, making excessive noise or not working correctly. Some compressors are
naturally noisier than others, but loud knocking noises can sometimes be caused by air in the
system (the cure here is to vacuum purge the system to remove the unwanted air, then to
recharge the system with refrigerant). Metallic noises and bearing noise are usually signals that
the compressor is about to fail. A new compressor may be needed if the unit is leaking internally
or not producing enough pressure due to bad reed valves, worn piston rings, or worn or scored
cylinders, etc.). A worn compressor or one with internal problems will not be able to develop
normal operating pressures with a full charge of refrigerant. This kind of problem can be