"UPdate"A/C is being a pain in my *ss

[Vindictus]

I have a bottle of Pag 46 oil left for last years install. I'm going to order a new dryer and orifice tube from rockauto just to be on the safe side

 

[Vindictus]

Just want to say thanks to rubydist, RonD, Shran and 55trucker for all your help and advice.

 

[55trucker]

I take it that you have a proper set of manifold gauges & a vacuum pump?
remember after drawing the vacuum on the system, at the point where you connect the cans of refrigerant to the center yellow fill hose ...keep the manifold handwheels closed, open the can valve, pressurize the line & *burp* the air out the hose going up to the manifold by backing off the hose fitting under the manifold for a second.

 

[Vindictus]

yes I have gauges and pump and know to bleed out the air. Thanks for making sure i'm not missing any steps. It's always good to have brain refreshed from time to time

 

[Eddo Rogue]

your compressor is probably junk. Mine only lasted one summer as well, then the autozone compressor crapped out. I replaced it and re did refrigerant process, but it wont blow as cold. I should have changed the orifice tube and maybe some other parts. will probably do it again next summer.

 

[Vindictus]

The Engine Computer(PCM) activates the AC Clutch relay when it gets the 12volt "demand signal" from the dash switch

In 2007 and up, 12v(fuse 27) is sent out of the dash switch and THRU the 2 pressure switches to the PCM pin 15
PCM will then Ground pin 14 which activates the AC Clutch relay in engine fuse box

Pressure switch should have a green/blue stripe wire, that's the wire to PCM, if that wire has 12volts then PCM will activate the AC relay
The 12v from the dash switch comes into pressure switch on a green/orange wire

PCM control allows the PCM to shut off AC if engine is over heating(ECT sensor) or if driver wants best power, i.e. Wide Open Throttle(WOT)
It also allowed PCM to turn on electric cooling fan in 2.3l models, with AC on

Ford used a Micro-relay for AC Clutch, seen here: http://www.gtsparkplugs.com/images/micro-automotive-relay-wiring.jpg

Pull out the relay
85 and 86 slots are the coil hook ups, key on, test both for 12v, only one should have 12v from engine fuse box fuse 43
The other slot is the Ground from PCM, there is no assigned 85 or 86 so can be either way
Start engine, turn switch on dash to AC
Test if this "other slot" is a Ground
If not then PCM is not getting the 12v from dash
If so then PCM is seeing the 12v so pressure switch is not the issue

Key off
Test slots 30 and 87, only one should have 12v, from fuse 25 in engine fuse box
The other one is the OUT to AC clutch coil
If you were to jumper these 2 slots together the AC clutch should activate, "click" if its working, engine or key on or off wouldn't matter, should still click as the coil becomes a magnet and pulls the clutch IN

Having more problems with a/c.
It quit yesterday and does not even try to start
I put manifold on it tonight with engine off both sides are 75 psi just like it was 2 months ago when I had bad o-ring

I pulled the relay and slot 86 had 12.39 volts, slot 85 is grounded
slot 30 has 12.66 volts key off, but when I jump slot 30 and slot 87 there is NO click

Do I have a bad pressure switch???

 

[RonD]

No, its the clutch itself

Jumping slot 30 to 87 sends 12v to the Clutch field coil, that should change it to a magnet and pull in the clutch plate and engage the compressor
The "Click" would be the plate being pulled in

This set up has an "air gap" that needs to be close enough so the magnet can pull in and hold the plate but wide enough so it doesn't rub when AC is not engaged
Shims are used, thin washers, to set the air gap


Bad pressure switch would mean slot 85 would not be grounded, so relay wouldn't activate

 

[Vindictus]

Thanks @RonD I'll play with the shims this weekend and see if I can make it last this summer

 

[RonD]

With AC turned on or 30/87 jumpered tap on the clutch plate to see if it goes in

If not test the Clutch coil with OHM Meter
Unplug the 2 wire connector
Connect meter to both contacts, 3 to 5 ohms is normal
No change in display means coil is broken inside, no connection
under 2 ohms is a short, that usually blows the fuse, but not always

 

[Vindictus]

The OHM on the clutch coil is 6.19

When I tap the clutch with 30/87 jumpered I can hear the plate move each time I tap it
Moves but doesn't seem to hold

 

[RonD]

6 ohms is OK, OHM Meters are not calibrated

Re-shim it, remove a shim to bring plate closer to coil, also inspect it, no debris stuck to anything
Replace coil/clutch if that doesn't work

 

[rumblecloud]

Is it supposed to hold when you jump it or is it just a momentary connect to confirm that it is working? I suspect it is the latter.

 

[RonD]

When 12v and ground is applied the coil becomes an electro-magnet..............so holds until 12v or ground is cut

Not momentary


Like the big cranes with electro-magnets used to pick up metal scrape, turn on the coil and it holds, turn off the coil and it drops the metal
Same unit just larger scale

It could be the coil is bad, it maybe separating when heated up(voltage applied) so 12v or ground is cut, not sure how you could test for that

Like a bad spark coil, tests fine but fails when in use, it happens
Hard to test low OHM devices
You can test if they are bad, but can't test if they are good, lol

If initial application of voltage causes it to pull the plate in, but it releases soon after without removing voltage then I would guess bad coil, too big of an air gap should cause intermittent engagement when applying power, I would think, but would hold after engagement