TR21 & TRS21 Piston Seal Diagnostics

Items needed:

Refrigerant Manifold /Hose Set with ¼ SAE connections

¼ SAE Female Brass Sealing Cap

Stop Watch

Test Procedure:

Connect the Manifold High Side Hose to Discharge (OUT) of the TR unit.

Connect the Manifold Low Side hose to Suction (IN) of the TR unit.

Make sure common (middle) port of manifold is open to atmosphere.

Close High and Low Manifold valves.

Start the unit.

Open Low Side Manifold Valve.

You should notice the High Side Gauge beginning to increase in pressure. Let the unit run until the High Pressure Switch activates (550 PSIG). The unit should reach 550 PSIG and cut out on High Pressure in about 30 seconds. This time is based on a 6 foot refrigeration hose. 3 foot refrigerant hose would take about 20 seconds.

After the unit either shuts off on High Pressure Limit or fails to reach High Pressure Limit at 30 seconds, close Low Side Manifold Valve and turn unit off. Observe the manifold pressure gauges as follows:

• 1. Monitor the low side gauge. If the low side gauge starts to rise and the high side gauge falls, this may indicate that one of the discharge valves in the compressor head may not be seating properly. See COMPRESSOR HEAD REPAIR-DISCHARGE VALVE for corrective action.

• 2. Monitor the high side gauge. If the high side gauge falls but the low side gauge remains at zero, there is a leak on the high side of the unit. See HIGH SIDE LEAKS for corrective action.

If no issues observed in items 1 & 2, continue with diagnostics.

Make sure the unit is turned off. The next test will determine if the piston seals are adequate. With the High Side Gauge at 550 PSIG, place a brass sealing cap on the common (middle) port of the manifold. Open the high side manifold valve. Then very slowly open the Low Side Manifold Valve until it reaches 100 PSIG, then close.

• 3. Monitor the Low Side Manifold gauge. On brand new unit, the pressure will be held or fall very slowly over time. As the seals wear, you will see the pressure fall faster. The rate of fall will determine the status of the piston seal.

a. Pressure drop from 100-50 PSIG should be longer than 1 minute to be acceptable for flammable type refrigerants. This timed pressure decay correlates into a .1% leak rate on the piston seals. If shorter than 60 seconds, proceed to PISTON SEAL MAINTENANCE/REPLACEMENT.

b. Pressure drop from 100-50 PSIG should be longer than 20 seconds to be acceptable for standard refrigerants. If shorter than 30 seconds, proceed to PISTON SEAL MAINTENANCE/REPLACEMENT.