My AC clutch is not engaging… I know a little bit of HVAC I’m a maintenance tech and I work on housing HVAC…anyhow I have a 2002 f150 lariat v8 I’ve checked the compressor diode fuse by swapping with another I’ve checked the clutch relay and 15amp fuse everything is good….my clutch won’t engage I’ve tried the paper clip to the relay and it doesn’t work I’ve tried jumping the low pressure switch it won’t engage but the only way I can get my clutch to engage is jumping the low pressure switch and adding 12v to the jumper and boom clutch engages….I’m lost neither low pressure switch or high pressure switch have 12v or continuity with truck running and ac max set to on? Is there a bad wire somewhere or broken? I’m completely lost and it’s HOT outside please help!

 

You sure it's charged? Checked the clutch air gap?

 

I’m not sure what charge it has since clutch won’t engage however with the low pressure switch u hooked shouldn’t I still be getting 12v at the plug? I’m getting 0v at the plug with ac on max EATC

 

You can check the static pressure with gauges. Should be around 100 psi both sides.

Have you done the EATC self test?

https://www.idmsvcs.com/2vmod/eatcswap/selftest.html

 

If the series pressure switch circuit does not have power, the PCM will never turn on the clutch. If the system cooled properly when you jerry-rigged it to engage, the pressures are not the problem, the control circuit is.

Assuming an EATC (it's a Lariat), power for that circuit is supplied from the EATC C228a-11 on a VT wire to the HPCO switch. It is fed through NC contacts in the HOCO switch to the LP cycling switch via a RD/YE wire. Power for the whole circuit is supplied by one of the two fuses that supply power to the EATC, fuses F24 and F02 in the CJB.

Check the two fuses.
Check the EATC self-test, as suggested.
Check the continuity of the circuit described above.
Report results or updates.

 

so I just replied a big message not sure where it went but idk I’m new to this site so today at work I ran the EATC test and I received 888 and a bunch of other stuff and google says that’s the correct display if everything is correct however I ran the EATC with the LP switch unplugged….forgot to rehook it back up…anyhow after getting home from work I went over everything again checked all my AC related fuses and pcm fuse everything is working has continuity and 12v while AC is on max however I’m lost now because both my high and low switches have power now?!? BUT when I jumped the LP switch like I did last night with 12v directly from the battery it won’t engage like it did last night when I did it last night I engaged it twice
for a good 5 seconds then left it alone what happen? Why do I have power now? Why isint the clutch engaging like it
did last night? I’m assuming I f it
up?

 

Ok so here’s an update….idk what happen I about gave up on it. Yesterday was really hot I tried messing with it after work if you can u understand anything I wrote lol any who today I started my truck feeling miserable knowing it was going to be hot today and my ac was set to max last night after messing with it so after starting my truck up ac max was already set and I heard a noise sounded like my clutch and after opening my
hood low and behold my clutch cycling on for 5 sec and off for 3 and I did absolutely nothing besides run the EATC self test so I’m picking up some guages today bcuz my ac feels cool but not as cool as I want so for anyone that has a Ford with an EATC my advice to you is run the EATC test FIRST b4 anything else because I think it fixed itself? Idk anyone’s input would be greatly appreciated.

 

Have you checked the clutch gap like glc suggested?

 

I haven’t but it looks very small and also I haven’t had a chance to pickup guages yet but I’ve noticed when it gets hot my clutch won’t engage is this a low Freon symptom?

 

The *only* way to ensure you have the correct amount of refrigerant is to vacuum the system down and "weigh in" the correct type of refrigerant. That's true for any package AC unit. It takes a while and a couple of special tools, but it's not difficult.
IMHO these little cans of "freon" should not be sold, they cause more headaches than anything else.
The only exception to weighing a charge in is when there's a line set whose exact length is not known or when switching refrigerants. In that case, you measure superheat. It's an accurate method, but weighing in is always dead on... and required when possible.

 

True, but an experienced AC guy can use a gauge set to get it close enough. The charge doesn't have to be exact for the system to work just fine. I've been charging my auto and home AC units for 50 years.

 

I miss the old days with sight glasses - just charge it till the bubbles stop.

 

Ok I picked up some feeler guages and the smallest it goes 0.038 in metric and the thickest is0.635 I have an f150 super crew cab v8 5.4 2002 does anyone know what the gap should be?

 

If no one responds, I'll look it up in my manual tomorrow. I keep my manuals in my truck.

 

thankyou I have my owners manual would it be in it? I’m pretty sure it’s my clutch gap I seen a YouTube video of someone pushing a stick against the clutch and if it engaged your gap is too far out but I pressed on mine b4 requesting it to kick on and when I hit max ac the clutch engaged