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post #1 of 5 (permalink) Old 12-14-10, 01:28 PM Thread Starter
yol
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1993 Taurus GL A/C problem

Hi all,

a couple of years ago i took my car to an A/C guy that replaced the compressor as the old one had a worn clutch. i did notice after he fixed it that he added a relay that activates the main radiator fan when the a/c is turned on. until today it worked ok. now it seems the relay is bad as it keep the fan working always. i disconnected it to avoid dead battery.
my question is - why is this relay needed ? dont the car "know"to operate the fan more often when i turn on the a/c ? or keep it working at minimum speed as long as the a/ is on ?

Thanks for any help !!

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post #2 of 5 (permalink) Old 12-19-10, 06:20 PM
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Question Re: 1993 Taurus GL A/C problem

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Originally Posted by yol View Post
Hi all,

a couple of years ago i took my car to an A/C guy that replaced the compressor as the old one had a worn clutch. i did notice after he fixed it that he added a relay that activates the main radiator fan when the a/c is turned on. until today it worked ok. now it seems the relay is bad as it keep the fan working always. i disconnected it to avoid dead battery.
my question is - why is this relay needed ? dont the car "know"to operate the fan more often when i turn on the a/c ? or keep it working at minimum speed as long as the a/ is on ?

Thanks for any help !!
Could you be more specific, he added relay or did he replace the CCRM (Constant Control Relay Module) under the warning label shield??? The PCM uses the CCRM to control the radiator fan, the A/C clutch, the fuel pump and power to the PCM.

Master ASE Certified L1 Chrysler Technician- still a Ford fan at heart.
1964 Thunderbird Hardtop- Chantily Beige- 390 FE 4V V8-Uncle's Car
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post #3 of 5 (permalink) Old 12-19-10, 07:35 PM Thread Starter
yol
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Re: 1993 Taurus GL A/C problem

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Originally Posted by tbird100636 View Post
Could you be more specific, he added relay or did he replace the CCRM (Constant Control Relay Module) under the warning label shield??? The PCM uses the CCRM to control the radiator fan, the A/C clutch, the fuel pump and power to the PCM.
Hi tbird, he put the relay in a way it bypasses the CCRM and activates the radiator fan. the relay's coil has a permanent grund and the activation comes from the compressor's clutch, the relay's common pole is connected to the wire that comes out of the CCRM and goes to the fan while the other pole of the relay has constant +12v .
i thought the CCRM or maybe the PCM had to know somehow that i turn on the a/c and then through the CCRM activate the fan as needed.
maybe the CCRM is either not getting the a/c on signal or its defective which makes the relay bypass a good idea.
if i disable the relay, the a/c will not cool although the compressor works.

thanks and merry xmas !!
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post #4 of 5 (permalink) Old 12-25-10, 12:51 PM
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Exclamation Re: 1993 Taurus GL A/C problem

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Originally Posted by yol View Post
Hi tbird, he put the relay in a way it bypasses the CCRM and activates the radiator fan. the relay's coil has a permanent grund and the activation comes from the compressor's clutch, the relay's common pole is connected to the wire that comes out of the CCRM and goes to the fan while the other pole of the relay has constant +12v .
i thought the CCRM or maybe the PCM had to know somehow that i turn on the a/c and then through the CCRM activate the fan as needed.
maybe the CCRM is either not getting the a/c on signal or its defective which makes the relay bypass a good idea.
if i disable the relay, the a/c will not cool although the compressor works.

thanks and merry xmas !!
The way it's supposed to work is you turn the A/C on and power from the control head goes to the A/C cycling switch and the PCM. The PCM then grounds the low speed fan relay coil in the CCRM to turn on the low speed fan. The fan stays on up to 45 MPH, when at that speed there's enough airflow that it's not needed, and the fan is shut off. When there is insufficient airflow through the condensor, when the radiator fan doesn't work, the A/C will not get cold. I have no idea why the guy would redneck a setup if there was a problem.

I'd remove the hack work, wire it back correctly and then see what happens. If it still doesn't work see what codes set in the PCM. Also disconnect the CCRM connector and check the pins for corrosion. Check the 60 Amp fuse in the fuse box behind the left strut tower too. Here's the diagram of the radiator fan itself.


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post #5 of 5 (permalink) Old 12-25-10, 01:12 PM Thread Starter
yol
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Re: 1993 Taurus GL A/C problem

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Originally Posted by tbird100636 View Post
The way it's supposed to work is you turn the A/C on and power from the control head goes to the A/C cycling switch and the PCM. The PCM then grounds the low speed fan relay coil in the CCRM to turn on the low speed fan. The fan stays on up to 45 MPH, when at that speed there's enough airflow that it's not needed, and the fan is shut off. When there is insufficient airflow through the condensor, when the radiator fan doesn't work, the A/C will not get cold. I have no idea why the guy would redneck a setup if there was a problem.

I'd remove the hack work, wire it back correctly and then see what happens. If it still doesn't work see what codes set in the PCM. Also disconnect the CCRM connector and check the pins for corrosion. Check the 60 Amp fuse in the fuse box behind the left strut tower too. Here's the diagram of the radiator fan itself.



ok, thanks for the schematics and advise, will check and post back...i still have to get/make myself the code blinker/display gauge...
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