Takeuchi TL150, Workshop Manual

Page: 131 / 312

III-88
3. Add refrigerant until the gauges read in the normal range and the sight
glass appears clear. The sight glass may not be clear for a moment just
before or after the clutch cycles on and off but should generally be
clear. Gauge readings will fluctuate as the compressor cycles on and
off.
Note: Pressures within the air conditioning system vary with ambient
temperature. A normal pressure range is defined as follows:
Low side 15–30 PSIG
High side 150–280 PSIG
If R-134a is used in place of R-12 the high side readings will
be about 20 PSI higher. For this reason many OEMs are recom-
mending an increase in condenser capacity when retrofitting to
the new refrigerant, R-134a.
If the gauges show any abnormally high or low pressures as
you are adding refrigerant, stop and investigate for probable
cause. Never add more than one pound of refrigerant. If the
system is low enough on refrigerant to require more than that
amount you should stop and check again for leaks. Then re-
cover all of the refrigerant, repair, evacuate and recharge the
air conditioner. (See
Chapter 9
). You may want to add dry
nitrogen gas to the AC system instead of R-12 if pressures are
below normal and a leak is suspected. Nitrogen gas is sold in
cylinders under high pressure, 1800 to 2000 PSI. Be sure the
cylinder has a pressure regulating valve to control the pressure
when dispensing nitrogen gas. Dispose the gas at no more than
200-250 psi, as this is sufficient pressure to cause or indicate a
leak point. See note under
Troubleshooting by Manifold Gauge
Set Readings
in this chapter.
4. When the gauges show normal, close the hand valve on the manifold,
the hose end shutoff valve, and the valve on the refrigerant container.
You can now proceed with the performance inspection.
3. Stabilizing The AC System
For reliable gauge readings as an aid in troubleshooting, the AC system must be
stabilized.
Be sure your tools and test equipment are clear of all moving
parts of the engine and air conditioner.
Manifold Gauge Set Installation
CAUTION
CAUTION