Another A/C Clutch not Engaging Post | Ford Explorer Forums - Serious Explorations

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Another A/C Clutch not Engaging Post

DA73

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May 12, 2016
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Year, Model & Trim Level
2003 Ford Explorer
Haven't been on here in a while but I've run into an issue I know nothing about. After searching the forum and reading others post along the same lines I still find myself a bit lost.

I drive a 2003 Ford Explorer 4.0L with 220k miles. The thing still runs like a dream (Knocks on wood) but it hasn't had working AC since I bought it almost 3-4 years ago. It's finally become a massive annoyance so I've been looking into it. First thing I noticed was that the clutch doesn't engage. But spins freely by hand.

I checked the fuses and relays, all were okay. However in the diode connected to the system I wasn't able to get continuity, as if it may be blown. I'm not certain how large a role the diode plays is this circuit however.

When I jumped the pins on the relay I was able to get the clutch to engage and spin. I only allowed it to engage for a single second then I disengaged it again for fear of damaging the system.

Under the assumption that the relay is fine, am I looking at a bad "low pressure switch" or could it really be that it is just too low on R134a? If it is low, then how can I recharge the system without the clutch being engaged to create pressure and draw in the refrigerant?
 






System most likely has a leak and has lost all the refrigerant. It is the pressure of the refrigerant in the system that closes the low pressure switch to activate the clutch/compressor. Should put a set of gauges on the system to see what reading you get if any. Common leak areas are the side of the receiver/drier (left side of rad), bottom of condenser, compressor seal as well as other areas. Frequently leaks are caused by acid forming in the system and eating holes from the inside out as is the case with the receiver/drier.
 






I pressed in the valve and some compressed gas (Assuming Air) escaped. Would this be an identifier that its empty? I'll check the exact pressure with a gauge tomorrow, what is the normal range for the high and low pressure lines?
 






The circuit to engage the compressor rarely fails. Never assume a circuit fault and fully charged system.

Static pressure should roughly be associated with the ambient temp as long as the car has been sitting for hours.
 






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