Mechanics

F150 REPAIR QUESTION

1997 Ford F-150

Air Conditioning problem
1997 Ford F150 V8 Two Wheel Drive Automatic 135000 miles

Last month the heater core assembly was replaced by an out of town Ford dealer for $1,100. The AC was working perfectly when I took it in, which I knew from trying everything to clear my fogged windshield. A few days ago I discovered that my AC now blows only HOT air.
I took it in today to my local Ford dealer who insists that I need a new temperature door accuator motor and that it's in no way a coincidence that the AC only quit working after the heater core repair was done by a different dealer.
He said that the accuator motor and heater core aren't even near one another so wouldn't have been affected.
I called another mechanic who refuted that and said that most likely the temperature door wire was disconnected during the heater core repair and not reconnected.
How do I go about determining the truth and not spending another $305 if not needed?
I greatly appreciate your expertise and time.
Randi
Avatar
Randira
March 12, 2009.



I go with mechanic B! Is this auto tempo control?
Test manual a/c like this:
A/C DOES NOT OPERATE OR DOES NOT OPERATE PROPERLY 1. Check A/C Compressor Clutch Operation Start engine and allow to idle. Turn mode selector switch to MAX A/C position. Turn temperature control knob to middle position and blower to medium-high position. Ensure battery voltage is 12 volts or more. If compressor clutch does not engage, go to next step. If compressor clutch engages, compressor clutch circuit is operating properly. 2. Check Clutch Cycling Switch Turn ignition switch to OFF position. Disconnect clutch cycling switch connector. Connect a jumper wire between clutch cycling switch connector Red/Yellow wire terminal and Black/Yellow wire terminal. Start engine and allow to idle. Turn mode selector switch to A/C position and blower motor control knob to HI position. If compressor clutch engages, connect clutch cycling switch connector and go to next step. If compressor clutch does not engage, go to step 4). 3. Check Refrigerant System Pressure Turn ignition switch to OFF position. Connect manifold set to service ports. If refrigerant system pressure is 50-400 psi (3.5-28.1 kg/cm 2 ), replace clutch cycling switch. Ensure system is operating properly. If refrigerant system pressure is not as specified, check refrigerant system for leaks or low charge. Repair and necessary. Ensure system is operating properly. 4. Check Voltage At A/C High Pressure Cut-Off Switch Turn ignition switch to OFF position. Disconnect A/C high pressure cut-off switch connector. Turn ignition switch to RUN position. Turn mode selector knob to MAX A/C position. Using a voltmeter, measure voltage between ground and high pressure switch connector Purple wire terminal. If voltage is 10 volts or more, turn ignition switch off and go to next step. If voltage is less than 10 volts, go to step 13). 5. Check Voltage At Clutch Cycling Switch Connect A/C high pressure cut-off switch connector. Turn ignition switch to RUN switch. Turn mode selector switch to MAX A/C position. Using a voltmeter, measure voltage between ground and clutch cycling switch connector Red/Yellow wire terminal. If voltage is less than 10 volts, go to next step. If voltage is 10 volts or more, go to step 7). 6. Check A/C Pressure Cut-Off Switch Continuity Turn ignition switch to OFF position. Disconnect pressure cut-off switch. Using an ohmmeter, check continuity between pressure cut-off switch Purple wire terminal and Red/Yellow wire terminal. If continuity exists, repair open in Red/Yellow wire. If continuity does not exist, replace A/C pressure cut-off switch. Ensure system is operating properly. NOTE: Ambient temperature should be greater than 50 °F (10 °C) for compressor operation.7. Check A/C Clutch Cycling Switch Continuity Connect manifold set to service ports. Ensure refrigerant system pressure is 50-400 psi (3.5-28.1 kg/cm 2 ). Using an ohmmeter, check continuity between clutch cycling switch Red/Yellow wire terminal and Black/Yellow wire terminal. If continuity exists, go to next step. If continuity does not exist, replace A/C clutch cycling switch. Ensure system is operating properly. 8. Check PCM Input Voltage From Clutch Cycling Switch Turn ignition switch to OFF position. Connect 104-pin break-out box to PCM Gray connector. Turn ignition switch to RUN position. Turn mode selector knob to MAX A/C position. Using a voltmeter, measure voltage between ground and break-out box terminal No. 41 (Black/Yellow wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair Black/Yellow wire. Ensure system is operating properly. 9. Check Voltage To Compressor Clutch Turn ignition switch to OFF position. Disconnect compressor clutch connector. Turn ignition switch to RUN position. Turn mode selector knob to MAX A/C position. Using a voltmeter, measure voltage between ground and compressor clutch connector Black/Yellow wire. If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair Black/Yellow wire. Ensure system is operating properly. 10. Check Compressor Clutch Ground Turn ignition switch to OFF position. Using an ohmmeter, measure resistance between ground and compressor clutch connector Black wire terminal. If resistance is one ohm or less, go to next step. If resistance is more than one ohm, repair Black wire. Ensure system is operating properly. 11. Check Compressor Clutch Coil Resistance Using an ohmmeter, measure resistance across compressor clutch coil terminals. If resistance is less than 6 ohms, go to next step. If resistance is 6 ohms or more, replace compressor clutch. Ensure system is operating properly. 12. Check Compressor Clutch Field Coil Current Draw Turn ignition switch to OFF position. Connect ammeter between compressor clutch field coil Black wire terminal and compressor clutch field coil connector Black wire terminal. Connect a jumper wire between compressor clutch field coil Black/Yellow wire terminal and compressor clutch field coil connector Black/Yellow wire terminal to complete circuit. Turn ignition switch to RUN position and measure current draw. If current draw is 2.5-4.5 amps, repair compressor clutch air gap. If current draw is not 2.5-4.5 amps, replace compressor clutch. Ensure system is operating properly. 13. Check Voltage At Mode Selector Switch Turn ignition switch to OFF position. Disconnect mode selector switch connector. Turn ignition switch to RUN position. Using a voltmeter, measure voltage between ground and mode selector switch connector terminal No. 1 (Light Blue/Pink wire). If voltage is less than 10 volts, go to nextstep. If voltage is 10 volts or more, go to step 16). 14. Check Voltage At Mode Selector Switch Using a voltmeter, measure voltage between ground and output side of fuse No. 5 (Light Blue/Pink wire), located in junction box fuse/relay panel. If voltage is less than 10 volts, go to next step. If voltage is 10 volts or more, repair Light Blue/Pink wire. Ensure system is operating properly. 15. Check Light Blue/Pink Wire Turn ignition switch to OFF position. Disconnect mode selector switch connector. Using an ohmmeter, check for continuity between ground and mode selector switch connector terminal No. 1 (Light Blue/Pink wire). If continuity does not exist, connect mode selector switch connector and go to next step. If continuity exists, repair Light Blue/Pink wire. Replace fuse No. 5 (15-amp). Ensure system is operating properly. 16. Check Mode Selector Switch MAX A/C Position Disconnect A/C high pressure cut-off switch connector. Turn ignition switch to RUN position. Turn mode selector switch to MAX A/C position. Using a voltmeter, measure voltage between ground and mode selector switch connector terminal No. 3 (Purple wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, replace mode selector switch. Ensure system is operating properly. 17. Check Mode Selector Switch A/C Position Turn mode selector switch to A/C position. Using a voltmeter, measure voltage between ground and mode selector switch connector terminal No. 3 (Purple wire). If voltage is 10 volts or more, go to step 5). If voltage is less than 10 volts, replace mode selector switch. Ensure system is operating properly. Page 1 of 1 A/C-HEATER SYSTEM - F150 & F250 LD -1997 Ford Pickup F150 3/12/2009


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Merlin2021
Mar 12, 2009.