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Old 07-02-2018, 04:00 PM   #1
wrenchboss26
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A.c. relay not getting power

2004 f150 4x4 5.4 ac relay isn t getting power. The relay kicks on but there is no power on the pink/blue wire to relay. I have laid in the floorboard and checked every fuse with a test light. Found one blown on an unrealated system and replaced it. If I apply power to the grey/black wire the clutch kicks on. Any suggestions? System has a full 134a charge. Reading 100psi on high and low side. Low pressure switch has been jumped. High pressure switch has been jumped.
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Old 07-03-2018, 02:21 AM   #2
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Re: A.c. relay not getting power

Jumping a high pressure switch will usually do nothing to a compressor-- they are usually normally closed switches and open with high pressure. Jumping it will de-activate your safety switch. Just because you read 100psi in system does not mean it is full- it means you have enough to energize the switches etc. You could have 5 ounces or 5 lbs in your system and it will read 100 psi- just a heads up.

Very rare to not have power to the input terminal of your relay- it usually comes straight from a 10 amp fuse right next to the a/c relay. I hope you test either with a DVM or a test light the back test probe holes of each fuse- just looking at the fuse element is no good- I have seen great looking fuses test bad... Just Sayin...

A lot of Fords use a CCRM- I guess yours is old- school
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Old 07-03-2018, 04:31 AM   #3
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Re: A.c. relay not getting power

The fuse is in the kick panel on the passenger side. The system has 33 oz if 134a installed by myself from a robinaire ac machine. The relay is on the drivers side in in the auxillary box along with the ac diode which protects the computer during clutch disengagement. It is very rare to not have power to the relay. That is why I'm stumped.
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Old 07-04-2018, 07:49 AM   #4
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Re: A.c. relay not getting power

May want to test the diode......I've seen them go bad....
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'99 IH 4700 Toy Hauler
(2) '95 GEO Prizms both maroon
'99 GMC Yukon
'95 Chev 3500, 454 Dually Crew Cab- 145k miles-
Wife's Camel trailer puller.
'94 Astro- 370k miles
'94 Firebird Formula- 5.7L 180k miles- gone-
'92 Chevy Lumina Van 3.8L 264k
'86 GMC S-15 - 2.8L 154k
'87 Buick Park Ave . 187k
'86 Buick Park Ave 3.8L 199k miles- gone
'77 Chevy Vega- 2.5L 175k miles gone but not forgotten
'68 Camaro 396 4 spd RS/SS -72k miles-
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