CPS TEMP-SEEKER TM360 Manual del usuario - Página 19

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EVAPORATOR FLOW CHART C

Measure the evaporator inlet and outlet temperatures as close to the evaporator core as

possible. The ideal temperature difference between the inlet and outlet is 0°F (-18°C).

The acceptable temperature range for the outlet tube is from 5°F (-15°C) colder to 5°F

(-15°C) warmer than the inlet tube. Readings within this range indicate there is adequate

refrigerant flowing in the system to transfer heat properly and carry the refrigerant oil out

of the evaporator, to the compressor.

Outlet Tube < 5°F (15°C)

Colder than inlet tube

CHECK SYSTEM FOR

Overcharge condition

Leaking o-ring seals at the orifice tube

Correct OT (orifice tube) for the

application (too large)

TXV (Thermal Expansion Valve) stuck

open

Notes:

•

Many systems (both OT (Orifice Tube) and TXV (thermal expansion valve)) do not

allow adequate access to the evaporator tubes for proper temperature drop testing.

As noted on page 11, (Technician Operating Tips), you may be able to gain access

by cutting a small section of the evaporator case away with a hot knife or vibratory

cutting tool. After completing the repair, reinstall the removed case piece and seal

with HVAC Permagum or insulation tape.

•

Variable Orifice Tubes (VOTs) are available for most applications that originally

had a fixed orifice tube. VOTs have been found to increase system performance,

lowering duct temperatures as much as 5-12 degrees F, at idle. VOTs are highly

recommended, especially in older vehicles converted from R-12 to R-134a.

•

An evaporator high-side outlet tube temp warmer than the low-side inlet tube

by 10°F (-12°C), or more indicates a restriction to refrigerant flow, or a very low

refrigerant charge. Check the high-side of the system for failures using Condenser

Flow Chart A.

Outlet Tube > 5°F (15°C)

Warmer than inlet tube

CHECK SYSTEM FOR

Undercharge condition

Excessive oil in system

Inspect orifice tube for restrictions (dirty

screen)

Correct OT (orifice tube) for the

application (too small)

TXV (Thermal Expansion Valve) clogged