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Trouble shoot my a/c problems

stevenf on Wed July 09, 2008 1:55 AM User is offline

Year: 1989
Make: Ford
Model: Bronco II
Engine Size: 2.8L v6
Refrigerant Type: R134

The a/c in my Bronco stopped working about two years ago. I have since then purchased a new dailey driver so I figured my Bronco would be a good place to start learning about the a/c unit.
When I turn the a/c switch on, the compressor does not engage. absolutely no noise comes from the compressor while outside with the hood up. When it first went out, we added coolant thinking it might have been low and that didnt help. My brother then bypassed a switch (I assume it was the low pressure switch???) with a wire and that didnt work.
At the time, we didnt realize that the compressor wasnt engaging because we didnt know any better. Now that I have my new truck and see the noise the compressore makes, I know the broncos isnt engageing.
I guess my next step would be to check if the clutch is bad....???? If so, how would I do that?

Chick on Wed July 09, 2008 5:54 AM User is offlineView users profile

Ok, we are happy you want to learn. But throw the death kit away..meaning the can with the single gauge and all the magic in the can... First, you need to determine if there is pressure in the system,, you can use that single gauge for that..If there is, then since you bypassed the cycling switch on the accumulator, try tapping the front of the clutch inwards, if it engages, then it's a clutch gap adjustment that is needed. Also check to see that 12 volts is getting to the cycling switch with the ac on, and also leaving it..Post back and we'll go from there.. Hope this helps..

1 once the ac does come on, feel the suction line, low side, to see if it's cold
2. don't run the compressor jumped any longer than to test pressures..If undercharged you can damage the compressor

Email: Chick


Freedoms just another word for nothing left to lose

bearing01 on Wed July 09, 2008 11:00 AM User is offline

Your 1989 has R134a in it... did you get it retrofited to R134a or did someone else?

You want to unplug the wire going to the compressor clutch and then jumper/bypass that low pressure switch like your brother did (make sure AC control panel has AC turned on). Then measure (with a volt meter) to see if you got 12V on the wire going to the clutch. If the electrical connector going to the clutch has two wires, measure each wire individually using the engine as your black-probe volt meter ground reference. If you got no voltage on either pin then it's likely an electrical problem. Go through all the electrical switches, etc.. between the clutch and the dash control panel. If you got 12V on one wire then either it's a bad ground (in the other connector wire?) or the clutch has an open circuit. You can measure the resistance of the clutch winding to see if it has an open circuit or not. You should only see a few Ohms on the clutch winding.

It could also be a voltage drop problem. If there's a corroded wire going to the clutch then once power is drawn by the clutch a voltage drop in the wire is created. Instead of getting 12.4V on the clutch you end up with 9V or so and that isn't enough to keep the clutch locked up. You could back-probe the electrical connector on the clutch to make sure you got 12V when its activated.

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