Have properly installed new A/C Compressor, Clutch, and Dryer. Tested system for leaks and vacuumed the system for approx. 40 min. Held a 30psi vacuum for 30 min. Then started to fill system. Also air gap is at .025 and added 7 oz.oil to compressor and 7 oz oil to dryer. hand turned compressor for about 12 turns before vacuuming system.
However, I have added only about 24-30oz of 134a and my clutch will not come on. I am nervous because I am getting a 100-102PSI on my low pressure and not even half the 134a the Hanes says it should take (68oz).
I tried jumping the low pressure sensor with a paper clip but did not force clutch on. fuses and diode visually look in tact.
Any sage advice would be greatly appreciated. Do I need to just proceed with the filling and the pressure will come down? My son is telling me he turned the rear A/C off so only the front was running. Would that have jumped the low side PSI?
Thanks in advance

 

If the compressor is not turning, you're just measuring the static pressure from the refrigerant container. You won't be able to put more refrigerant into the system until you get the compressor clutch to engage to suck it in.

With that much static pressure and a jumpered low-pressure switch, it can only be concluded that you have an electrical circuit fault that is preventing clutch engagement. Since you didn't identify the year and engine of your Exc, it's not possible to look up the correct diagrams.

 

Whoops, sorry. 2000 XLT 2WD 6.8L V-10. I am reasonable sure that the cutch, although new, is defective. I cant get my meter on it because the connection is in such a difficult location on the gas model. My friend bought a a/c compressor from the same parts house and it to came initially with a defective clutch. He was having it professionally installed so they took the mechanics word for it and replaced it. Since I am not employed as a mechanic at this time I am having to jump through hoops to have them warranty it.
But I thought you could jumper the relay and force the clutch on. I was really hoping to do this so I could at least know if the clutch was ever going to engage or not. In retrospect I should have tested it right out of the box. Live and learn the hard way - story of my life.
Cheers

 

Take the connector off the clutch and check it with a test light, do you have power at that connector? As you have done, you can jump the pressure switch to make the clutch kick in.

 

You may have to reset the computer on this model, they are controlled by the body module, when the compressor is not running, both gauges should read equal, the system always equalizes so it doesn't start the compressor with excessive head pressure, disconnect the battery and wait or scan tool it and reset KAM. clutches are pretty reliable it's just a winding, you can even ohm out the coil and anything but OL is good. If your HPCO and your LPCO have more than 2 wires going to them there not switches but sensors that the ecm reads and adjust the system accordingly. Days of jumping switches and putting power to compressors is over my friend.

 

You might be surprised how much you can still do once you understand how the system works... Also, there isn't a body module involved, the compressor is controlled by the PCM. There is no need to reset the computer...


Yes, it's a PITA. It might not be necessary, though.

Open the battery Junction Box under the hood and identify the A/C clutch relay (see owner's manual). With the engine running, have an assistant switch the A/C mode switch ON and OFF several times. If the relay is being commanded to energize, you should feel the relay click with your finger.

If it doesn't click, it's probably a pressure switch or other problem that's not communicating to the PCM that compressor operation is required. Check the low and high pressure switches (jump them, they're only two wire switches) and see if the relay energizes and the clutch pulls in. Verify you have 12 volts at each of the wires on both of the switches when connected.

The input side of the circuit is a series circuit consisting of under dash fuse F24 > MODE switch > Low Pressure switch > High pressure switch > PCM input. If you have a capable scan tool, you can "read" the A/C request signal that the PCM is "seeing" to see if a valid request is present (or not).

If the relay energizes, it's supposed to route power from under-hood fusebox F6 to the clutch coil to energize the clutch.

Since you have an ohmmeter, turn off the truck, pull the AC clutch relay, identify the #87 terminal in the socket, then perform a resistance check between the fusebox socket pin for #87 to vehicle ground. If the clutch coil circuit is good, you should read around 3-5 ohms at this point. If you read an open circuit, then either the coil is open, the connector isn't mating properly, or there's some other damage to the wire or connector that is preventing a completed circuit.

If the continuity check is good, install a jumper from relay socket terminal #30 to #87 and you should hear the clutch click in. If it doesn't check fuse f6 (Always hot).

That will give you some checks to make to see what works (or doesn't).

 

I'm mobile, and can't do the deed. Can someone rep out SHO? Great posting, and he needs more greenies! C'mon all you heavy hitters.

 

Got em!

 

Got him too

 

Thanks boys, went through the search and tested the relays and diode. Ended up having a blown fuse at #24 in the engine fuse box. It was barley blown so the first visual inspection was deceiving. Replaced it with the airbag fuse temporarily and viola a/c clutch! Now no blower motor so off to Autozone hopefully one last time!
Replaced motor continued filling alls well blowing 62 degrees on a 102 degree day.
One last question low side is 54 psi but high side is only 225 psi does this seem correct for such a hot day? My Gauge set guide says high side should be about 315-325 for 105 degree ambient temp?
Thanks in advance.

 

Making good progress! Glad the electrical stuff is resolved.

Here's a P/T chart that works for most Fords, courtesy of another of this site's users:



Unless you flushed the system as part of the repair, I suspect it might have too much oil in it. 14 oz is correct for a dual-air system that has no residual oil in it. Otherwise, the replacement compressor is a bit weak.

 

^^^^ Good stuff, reps sent ^^^^^

 

Thank you projectSHO89 you have been great help getting through several of these challenges. Was 105 here most of day and a/c was ice cold. I did not "flush" the system so you may be correct in that it is over oiled. I will put the gauge set on it after the weekend. I hope it is not a weak compressor. would hate to have to start over and evac and recharge.
Thanks again for your charts and assistance.

 

I put a compressor and desiccant sock on a Lexus the other day. A new Denso compressor comes with enough oil charge for the entire system. I measured the oil from the old compressor, 1oz. Drained the oil from the new compressor and then added back 1oz of fresh oil to match the old and less than an oz in the condenser. I charged the system and hit the road, 60 degree vent temp on a 95 degree day was the best it would do. I evac'ed the system and pulled a 45 minute vacuum, recovering 3oz of oil. Must have not got all the oil out of the new compressor. I charged the system back and went to the road again. This time I had 44 degrees out the vents. To much oil can make a big difference.

 

I see that this has been repaired but I thought maybe I could throw 5 cents in according to an 2002 wiring diagram if you have manual controls in no way is the PCM controlling anything. If you have auto controls the dash unit controls it not the PCM. Both of which should allow you to jump the low pressure switch to kick it on. I have ran into some fords that require this before the pump will kick on and you get some refrig. Flowing