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

information to 940 CCOT A/C systems. Included at the end of the review is a breakdown by
model. Information on model years is stipulated when known to be true; otherwise model
information is suggested as being "possibly earlier" or "possibly all models" because of the
inability to verify this information at the time of writing. Model years are included where known.
The purpose of this review is not to include every screw, pipe, and switch in the A/C system, but
is merely to educate about the fundamentals of two different kinds of A/C system found in RWD
Volvo models from the mid-1980s to 1998.
940 Models This system also applies to 700 series cars and 960 models. It also applies to *ALL*
240 models from 1991-1993. The mechanics of the system are the same between climate
controlled and non-climate controlled systems; electronics vary and are beyond the information
covered in this review. The 900 system is a clutch cycling orifice tube system, abbreviated
CCOT. The CCOT system cycles refrigerant through the following components:
1. Compressor begins high pressure cycle at compressor outlet.
2. Condenser
3. Fixed orifice tube (locations vary slightly, ALL are high side fixtures) *** Transition from
high pressure to low pressure side via Fixed Orifice Tube ***
4. Evaporator (downstream of F.O.T.)
5. Accumulator-dryer. NOTICE this is on the LOW SIDE
6. Refrigerant returns to compressor via suction side.
The CCOT system has the accumulator-dryer (large silver can at the firewall) on the LOW
PRESSURE SIDE. It is suitable to charge into the accumulator, as is plainly evidenced by the
presence of a charge valve attached to the same low side pipe adjacent to the accumulator.
Again, it is STRONGLY recommended that anyone who is unsure about the components of an
A/C system, avoid work until a time at which they have become sure about it. Damage to the
system, and injury can result. Verify all information before attempting any air conditioning repair
or maintenance. As a review, here is a breakdown by model: CCOT systems (GM-type) 240
1991-1993 ONLY; 740 1988- (unable to verify, should be all 740 models); 760 1988- (unable to
verify, should be all 760 models); 940 all; 960 all; S90/V90 all.
Recommended System Maintenance When the System is Open. As soon as you have warm
weather, evacuate your A/C, raise the front of the car, remove the air guide (not engine pan)
and front grille. Disconnect and mark or identify the three connectors at the bottom of the
condenser on the passenger side. Unbolt the lines in and out of the condenser. Cap or cover
with tape those lines to keep air and humidity from entering the system. Undo the clamps that
hold the radiator in place, push the condenser up from its moorings and pull it out from under
the car. Undo the screws that hold those plates at the bottom of the condenser and put plastic or
rubber plates between the steel plates and the condenser to keep metal to metal contact
between steel and aluminum. Perhaps the plastic-like shims that come with Volvo rear brake
pads will do the trick. This is a good time to flush that condenser before you put it back in the
car. While you are under the car, you may want to remove the engine pan and take out the A/C
compressor to flush it and refill it with fresh oil. Sanden specifies Sanden SP-20 oil (8.45
ounces), but I think this is PAG 100 oil, perhaps with additives. Eight ounces of PAG 100 should
do in a pinch to refill the compressor. Taking the compressor out is not bad if done from under
the car. If possible, put in an Airsept screen in the suction line at the compressor. Airsept has