Takeuchi TB175W, Руководство по ремонту

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III-78 TB175W
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 compres -
sor 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 rec -
ommending an increase in condenser capacity when retrofit -
ting 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
recover 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 pres-
sures 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 mani-
fold, 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 mov-
ing parts of the engine and air conditioner.
Manifold Gauge Set Installation
CAUTION
CAUTION