Kubota B2630 Operator's Manual page 97

A Do not disconnect any part of the refrigeration
circuit of the air conditioning system. Consult
your local KUBOTA Dealer for assistance and
service.
A shortage of refrigerant impairs the air-conditioner
performance. Check the following points. If it is indicated
that the amount of refrigerant is extremely low, ask your
dealer to inspect and charge.
C Checking procedure
1. Run the air-conditioner in the following conditions.
A Engine speed:
A Temperature control lever: Maximum cooling
A Fan switch:
A Air-conditioner switch:
2. Look into the sight glass to see if the refrigerant is
flowing through its circuit.
(1) Sight glass
A Charge only with R134a not R12 refrigerant (gas).
About 1500 rpm
position (leftmost)
Highest blow (HI)
ON
PERIODIC SERVICE 77