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

700/900 92
B204/234/
Diesel
R12 1050 950
700/900 92 Other R12 950 900
900 93- 4-cyl R134a 950 950
900 93- 6-cyl R134a 950 950
Belt Squeeling After Recharge. [Symptom] After recharging my a/c system with R134, my
compressor belt squeels and the clutch will only operate when I apply direct battery power to it.
[Duane Hoberg] You've overcharged your system. The high system pressures caused the
compressor to lock up which caused the squeeling since the metal-to-metal clutch was slipping.
Place a gauge on the low pressure test port and if above 40psi on the low side (R134), bleed
some off and get the low side pressure to about 28psi.
Air Conditioning: R134 change from R12 in Volvo cars.
Basics on Air Conditioning R134 Retrofit.
[Tip from Larry Carley, Underhood Service, April 1999] In most instances and in most vehicles,
a "basic" R134 retrofit procedure is all that’s required to retrofit an air conditioning system. By
basic, we mean recovering any residual R-12 that may still be in the system, draining out the old
mineral oil, replacing the accumulator or receiver/dryer, and then evacuating the system to
purge air and moisture, adding the specified amount of POE oil for the compressor and
recharging the system to 85 to 90 percent of its original capacity with R-134a. It’s important to
remember that R-134a or any other alternative refrigerant cannot be mixed with R-12 or used to
top off an R-12 system. If an A/C system still contains any R-12 at all, it must be removed using
approved recovery equipment (venting is not allowed) before a new refrigerant is added to the
system. This is an absolute must to prevent cross-contamination of refrigerants and cooling
performance problems. R-134a and mineral oil won’t mix. So if somebody recharges an R-12
system with R-134a and doesn’t add a compatible lubricant, the compressor will soon fail.
Volvo was the first auto maker to approve POE oil (P/N 1161442-7) for R-134a retrofits. Volvo
retrofit kits include a new receiver/dryer and O-rings (color coded yellow) for the expansion
valve, and a new expansion valve or orifice tube. Volvo says the system should be evacuated
for at least 50 minutes following recovery of the R-12 and component replacement to pull out as
much residual R-12 as possible. Volvo also says the shaft seals on Sanden 508 and 510
compressors must be replaced when converting to R-134a. The new seal is P/N 9134344-2. If
the compressor is being replaced, it should be filled with POE oil through the fill plug only, never
through the inlet or outlet ports. Also, if the compressor is being replaced, Volvo says not to add
oil to the receiver/dryer.
[Editor] At conversion, consider adding both a variable orifice tube and an in-line filter in the
compressor suction line (both described below) to your system to improve low-end cooling and
protect the compressor against any system debris.