Insufficient Or No A/C Cooling

NOTE: A continuously running A/C compressor is considered normal when ambient temperature is greater than 80°F (27°C) and high humidity conditions.

Check A/C Compressor Clutch

If the A/C compressor clutch engages, proceed to the next step. If the A/C compressor clutch does not engage, proceed to COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS .

Check Pressure & Compressor Clutch Cycle Rate

Connect manifold gauge set. Set function control to MAX A/C. Set blower to highest speed. Set temperature control to full cool position. Close all doors and windows. Install thermometer at center discharge register. Record outside ambient temperature. Run engine at 1500 RPM with compressor clutch engaged. Stabilize A/C system with above conditions for about 10-15 minutes. Compare manifold gauge readings to normal system pressures. Low side pressure remains constant at 22-50 psi (1.5-3.5 kg/cm² ) throughout normal operating range. See A/C SYSTEM HIGH SIDE PRESSURE SPECIFICATIONS table. If clutch does not cycle rapidly (5 seconds on, 5 seconds off) and system pressure is within limits, A/C system is operating properly. If compressor cycles rapidly (5 seconds on, 5 seconds off) and low-side pressure is within limits, go to next step. If compressor cycles on at greater than 52 psi (3.7 kg/cm² ) and off at less than 21 psi (1.5 kg/cm² ), replace A/C cycling switch (also referred to as clutch cycling pressure switch). After replacing switch, verifyA/C system operation. If system still is not operating properly, reinstall original switch and go to next step.

A/C SYSTEM HIGH SIDE PRESSURE SPECIFICATIONS

Application Ambient Temp. °F (°C)		psi (kg/cm² )
Aerostar, Explorer & Ranger
60 (16)		120-210 (8.4-14.8)
70 (21)		140-220 (9.8-15.5)
80 (27)		160-250 (11.2-17.6)
90 (32)		180-270 (12.7-18.9)
Bronco, "E" & "F" Series
60 (16)		75-175 (5.3-12.3)
70 (21)		100-200 (7.0-14.1)
80 (27)		128-230 (8.9-16.1)
90 (32)		150-260 (10.5-18.3)

Check Pressures

Disconnect blower motor connector. Check low pressure gauge for pressure at which clutch cycles off. If clutch cycles off between 22-25 psi (1.5-1.8 kg/cm² ) and ambient temperature is more than 80°F (27°C), A/C system is operating properly. If clutch cycles off at less than 22 psi (1.5 kg/cm² ) or greater than 52 psi (3.7 kg/cm² ), go to next step.

Check For Leaks

Leak test system. If leaks are found, repair as necessary. Evacuate and recharge system. Recheck A/C system for leaks. If no leaks are found, refrigerant charge is low or there is moisture in the system. Evacuate and recharge system.