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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 34446
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Hi, my 2002 Ford Ranger AC compresser/solenoid does not engage

Resolved Question:

Hi, my 2002 Ford Ranger AC compresser/solenoid does not engage until after about 10 minutes of running the engine. I thought it was underchaged so added AC coolant, but no diff, then I thought over charged and removed some, no diff, so the AC fluid is def. not the problem. After the 10 min. wait, it cools quite well, but I live in Phoenix AZ and this 10 min wait is pretty hard to put up with. Any ideas will be appreciated. Thank you. Eric.
Submitted: 6 years ago.
Category: Ford
Expert:  Ron replied 6 years ago.
Chat Conversation Started
Ron :

Hello, When the AC is turned on start with checking to see if you have power in and out of the pressure cyycling switch that is mounted on the Accumulator. See the diagram.

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Customer:

Thanks, XXXXX XXXXX will check that and get back.

Ron :

Ok, let me know

Customer:

Hi, if that is the wires that plug into a module located near the low-side port then I have check that, and here is what I got.

Customer:

ooops, continued:

Ron :

What did you find?

Customer:

There is a black wire and a red wire in a plastic black harness that plugs into a small input near the low pressure port. I pulled the black plug with the wires out, and measured the voltage between the black and the red. With my red probe on the Red wire and black probe on the black wire, it reads 0 with the engine off, and it reads -13 volts (negative) with engine running, but AC turned off. I reattach and turn on AC but clutch not engaged, hot air, voltage check is still -13, then put back, then after 10 minutes AC kicks in, take off wires and check to find still -13 volts.

Ron :

It need to be checked with the AC on and the voltage needs to be 12 volt plus.

Customer:

with ac on it is 13 V.

Customer:

I will be back later, thanks.

Ron :

Try jumping it across the connector and see if the clutch runs/

Customer:

Hi, this morning before jumping across the connector, I remeasured the voltage. Start Engine , ac switch "off" , 4-5 volts. AC switch "on" 4-5 volts, and no clutch engaggedment. Then during the next several minutes the votage gradually increased varying between 7-8-9 volts.

Customer:

When it was in the 4-5 volt range I jumped across the connector but the clutch did not engage.

Customer:

I replaced the connectors into the socket, and after a total of about 10 minutes or so the clutch engaged cool air emerged.

Customer:

Summary so far: on engine start from cold, no a/c for 10 min. Volttage at pressure cyycling switch that is mounted on the Accumulator around 4-5 V then 7-9 volts. Forgot to mention: once clutch engages finally, voltage at pressure cyycling switch is steday at 13-14 V.

Customer:

I think my previous readings when starting the engine and finding 13 V were real, but I cannot explain it, then today 4-5 volts.

Customer:

Thanks.

Customer:

Also when I jumped across the connector, the engine revved a little, sort of wavered, but clutch did not engage.

Ron :

I would now check and see if the clutch relay has the correct amount of power in and out of it and if so, suspect the relay may be the fault.

Ron :

Here is the flow chart.

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Customer:

Hi please tell me where (under the hood) I can find the clutch relay so that I can check the power there.

Ron :

The clutch relay is in the under hood fuse panel (battery junction box).

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Customer:

Hi, I removed the relay, and measured the voltage in the socket slots. 14 V into and out of the relay . Thanks.

Ron :

have you ever checked to see if you have 12 volts at the clutch when it dosnt engage?

Customer:

There is a plug with two wires going to the compressor, just behind the pulley, I suppose this is the clutch solenoid. The power to the plug when the engine is running and as soon as the AC was switched on is wavering from 6-9 volts. After fluctuating for a while, it then suddenly goes to 14v steady.

Customer:

this is about the same pattern as what I saw with the press. cycling switch on the accumulator.

Customer:

thanks.

Ron :

Then you have a voltage drop in the circuit, the power source is the AC compressor clutch relay which is controled by the PCM, go back to your relay and see if you have the same voltage there,

Customer:

Hi, every  since I removed the relay to check the voltages INSIDE the recepticle, and then replaced the relay, the ac has been acting much better.  It still takes time to engage, but only about 1 minute.  So I think it is the relay itself.  The voltage inside the receptical was always 14V and 14 V (primary and secondary) so I will try buying a new relay at the auto parts shop. Thanks for your guidance.

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