MAHLE RTI RRC750X - Manual (Page 15)

Refrigerant Technologies, Inc.
May 24, 1993 Page 14
PROBLEMS & SOLUTIONS
On rare occasion the RR750X may seem to be performing differently or not at all. Experience has
shown that varying operating conditions can affect the performance characteristics of the RR750X.
The temperature of the vehicle A/C System will affect how the RR750X performs.
Following are typical problems with explanations of the possible cause and solution.
PROBLEM: My RR750X worked fine all last Summer. I got it out today for the first service job
this Spring and it is very slow in evacuating the system.
SOLUTION: Today's Spring temperature may be much lower than the average temperatures
during the summer months. Maybe the vehicle was brought in from outside where
the temperature is very low.
The refrigerant in the vehicle will not be under as high a pressure at lower
temperatures and the RR750X will take longer to draw a vacuum. More cycles may
be required to completely recover the refrigerant.
PROBLEM: I used the RR750X to service an A/C system earlier today and it worked great. This
afternoon it won't recover. The Compressor-On Light doesn't even come on.
SOLUTION: The pressure switch on the Suction Accumulator has a close-on-rise setting of 3 ±
3 PSIG. If there is less than 6 PSIG of refrigerant pressure in the vehicle's A/C
System, the RR750X may fail to start.
Connect a source of refrigerant pressure (for example, the External Cylinder) to the
Inlet Port of the RR750X. This will reset the pressure switch so the RR750X will
run when reconnected to the vehicle A/C. It will continue until a vacuum is
achieved.
PROBLEM: I can not get the RR750X to draw a vacuum.
SOLUTION: Connect the Gauge Manifold to the Oil Drain Valve on the RR750X. Close the Inlet
Port and, with the unit running in Recover/Reclaim Mode, determine if a vacuum
can be drawn. If yes, check the charging hoses and Gauge Manifold for possible
obstructions.