AC will not blow cold

[Eddie Lanham]

Less than a year ago I replaced the AC compressor, relay, and fuses that deal with the AC compressor. Recently checked all fuses and replaced the relay for 10$ just for ***** and giggles..

Problem is the AC won’t blow cold, and the clutch will not engage. I’ve tested the wiring to the compressor with a test light and I do have power. Wiring is not frayed or damaged. Really not leaning towards an electrical issue. It’s winter season here so I have not used the AC since September-October and I did not know how low the Freon was prior to the winter. It’s not december 14th and here’s more clues.. ac system will not take Freon, and has a very low amount of pressure in the system. I’ve read about low pressure lockouts but I can’t seem to find a “low pressure switch” to replace to maybe fix the problem. Anyone know where it’s located? Usually by the classic canister looking condenser but this model has a radiator style condenser so it’s kind of confusing.

I’ve tried to bang the compressor with a hammer to get it to engage, hand spun the clutch, smells burnt, there IS power going to the compressor, but no luck. Even tried to jump start the clutch but no luck either.

not sure if the low pressure switch can cause the compressor to not work, or if I’m thinking too deeply and my compressor shit the bed. Any help is useful , thanks!

2004 expedition 4.6L Edie Bauer

 

[Eddie Lanham]

@stamp11127

 

[Eddie Lanham]

@stamp11127

I know you’re a guru, any knowledge is always appreciated brother !

 

[riphip]

Never hammer a compressor. 'Freon' has probably leaked out as you have noticed. System will not receive 'freon' unless compressor is running or system is in a vacuum (compressor not running). Look on all lines for green/yellow oil to find evidence of leak, repair then pull vacuum and see if it will hold (I keep mine under vacuum for 12 hours myself0 then recharge system.
I am not sure if you can jump any connections to make compressor come on on low 'freon' on these since high/low pressure sensors, etc are involved.
Don't know what AC tools or experience you have but visually finding the possible leak is a start.

 

[Hamfisted]

The low pressure cutout switch is in the front expansion valve up by the firewall. I've only seen the low pressure switch come complete with the Motorcraft YG386 expansion valve, I haven't seen it sold separately by itself. You can try jumping the harness plug with a jumper wire and see if you can get the compressor to kick on. Other than that there's the high pressure cutout there by the high pressure service port. Those are sold separately. What are your static pressures high/low if you have a pressure gauge set?


https://www.amazon.com/dp/B000C5C47K/ref=au_as_r?_encoding=UTF8&Make=Ford|54&Model=Expedition|662&Year=2004|2004&ie=UTF8&newVehicle=1&vehicleId=1&vehicleType=automotive

 

[04WHITEEDDIE]

I'm not an expert in this area , but if your getting power the the compressor clutch and it won't engage, would that point to the magnetic clutch coil? You mentioned that it smelled burnt....which maybe the insulation that got overheated/ burned out from a short or ground in the clutch coil?

 

[Dustin Gebhardt]

I agree with @04WHITEEDDIE . If the compressor is getting power, the clutch should be engaging. The upstream sensors should prevent power going to the compressor clutch if any of them are faulted out. As others have said, what do your gauges say? With everything off and settled, what is your static pressure? When you turn on the engine, what is the high/low pressure readings? With a voltage meter (or test light), what are the incoming and outgoing voltages at each sensor?

The AC system is fairly easy to troubleshoot, but you will need a set of gauges to do it right. Similarly, a UV light will help pinpoint any leaks (assuming UV dye indicator is used) if you have them. In my '07, I have 3 sensors before the compressor (in no certain order): high pressure, low pressure, and evaporator box temperature. My evap box sensor doesn't work, and it's a real PITA to replace, so I jumpered a resistor across the connector and it works well. I also used to sit in a lot of hot, stop & go traffic while crossing the US/Mexico border, so I installed 2 electric fans in front of the condensor, which I wired to a relay that took its signal from the AC compressor power wire. Whenever the compressor would see power, the electric fans would spin up.