A/C Clutch not engaging

[BrooklynBay]

The valve that you are looking for is near the cut out switch. I didn't look at the layout of your truck, but it should be on, or near the accumulator which has the desiccant bag inside of it. That line also has the expansion (orifice) valve going into it.

 

[rgoers]

The valve that you are looking for is near the cut out switch. I didn't look at the layout of your truck, but it should be on, or near the accumulator which has the desiccant bag inside of it. That line also has the expansion (orifice) valve going into it.

Mine was near the passenger-side firewall. Right on the accumulator (can shaped thing with rounded top). On mine, the high and low side has a different size fitting, so you couldn't confuse them. Not sure about a '94 though. Mine's a 2000.

 

[insane3082]

i need help with my ac it died out couple days ago it was working fine but i no longer hear the compressor kicking on when i press the button for a/c i was told there is no power going to the compressor and that i should look into changing the relay only thing is i dont know where its at nor what it looks like. its my first car it runs fine but out here in chicago its getting too hot to not have a/c :fire: lol

 

[rgoers]

Could be lots of things

I'd start with the simple first. When it was working - was it ice cold? If it was getting warmer... it could just need a can of R134. If you think the charge is okay, I would try jumping the pos terminal of the clutch to the pos terminal of your battery. The pos on mine (2000 Sport) is the lower terminal of the 2-pin connector on the clutch. Turn off the engine, hook a wire to the connector, then start the engine, and lastly - touch the wire to the pos terminal of the battery. If the clutch engages, your charge is probably low.

 

[insane3082]

the compressor works turns on and all, well with what u said on top how to check for the clutch. but one more thing could the can not having any air be the problem? i pressed the pin to check and no air comes out.

 

[rgoers]

the compressor works turns on and all, well with what u said on top how to check for the clutch. but one more thing could the can not having any air be the problem? i pressed the pin to check and no air comes out.

There is a low pressure switch. Without pressure, the compressor will not run.

 

[Vermonter]

ok i ll try and keep this simple check to see if you have power going to the compressor buy 1st unplugging the connector at the compressor start the truck turn the ac on then use a test light or volt meter to see if you have power there, if not check for an open somewhere or check relay and trace it down ie fuse wiring in the eng compartment or the ac switch in the truck. if you do have power at the connector turn off the truck, see if you can turn the compressor by hand, if so good if not have the compressor replaced. if you can turn the compressor the check to see if the electromagnetic clutch is working HOW?????
ok the connector on the ac compressor has 2 pins or tabs 1 is ground 1 is the + feed to the compressor , with a 12 volt test light hooked to the positive battery terminal touch each ac connector (at the compressor) with the electrical connector un plugged when the light lights up that will be the neg or ground side, now replug the connector buck on to ac unit.
now this time use a 12 volt source without the light and back probe the + POSITIVE wire this should energize the ac clutch, you should here a loud click if you do start the truck and again send 12 volts to the positive side of the compressor and see if the clutch locks up and starts running if so then only run that for 2-3 seconds that is to test the clutch,
now you need to check the freon level WITH GAUGES!!!!!!!
if it s low, add freon as if you would but youll have to energize that ac clutch to draw the freon in with a 12 volt supply at the compressor.
with the clutch running and the ac on full blast youll need to check the gauges but the low side should read from approx 28-34 , becareful wear safety glasses if your not sure have someone who does know help you you might need a manual to check the correct pressure ,

ps if you have good pressure and the system still won t go on it will probably be 1 of acouple switches high or low side switch .....

I just had my AC system recharged and leak tested. I was told it was good to go, but I still have no AC. The compressor isn't kicking in at all, so I plan to do the above steps. One part I have a question on. When you say..."now this time use a 12 volt source without the light and back probe the + POSITIVE wire"...what do you mean by back probe?
Thanks

 

[rgoers]

That simply means to connect a 'jumper' wire to that terminal. On mine, it was the lower pin, as seen when connected properly.

I don't understand how someone could charge your system, and leak test it, if your A/C isn't working...

 

[Vermonter]

That simply means to connect a 'jumper' wire to that terminal. On mine, it was the lower pin, as seen when connected properly.


I don't understand how someone could charge your system, and leak test it, if your A/C isn't working...

The connector I have has the pins side by side not one above the other.

Exactly what I thought when I saw the compressor clutch not turning I could see that happening if the system wasn't leaked tested first, but it was (supposedly). I'll stop in tomorrow to see if he did the test & charge or if his assistant did it. Maybe it just needs to a tad more freon

 

[EvilleDave]

Sorry for the double post in the other thread but this is the thread I was reading when I wrote the reply, just replied in the wrong thread.


If I'm reading all this correctly I have bigger issues.
I checked all the fuses and relays.
I checked the plug at the compressor(no power)
I jumped the low pressure switch(nothing)
The cheapo gauge with the kit shows in the red but when I hit the needle valve there doesn't seem to be much pressure in it, I've recharged many times before.

I can't remember if I checked continuity at the plug but at the compressor side of the plug show no continuity showing either as ground. I'm on a limited income and would like to have this fixed, the wife is on oxygen as it is.


EDIT: When applying the 12 volts to the compressor do you also have to supply a ground?

 

[EvilleDave]

Decided to go out one more time. I tested the continuity on the low pressure switch and it was fine. So I say what the heck, I'm going to try the high pressure switch. There was no room to get into the switch to check for continuity so I just started the car with the AC on and jumped that plug, the clutch started working. I immediately pulled the wire but it stopped each time. I decided to put the gauges on it again and it showed just a bit low when I jumped the plug. I gave it a few "jumps" then hooked the plug back up and it works.

I'm not sure what the deal was here, maybe just a bad connection at the high pressure plug. Just something else to look at when all else fails. Thanks again to this site, it didn't solve my problem but gave me the kick I needed to look farther into it.

 

[james801]

ok i ll try and keep this simple check to see if you have power going to the compressor buy 1st unplugging the connector at the compressor start the truck turn the ac on then use a test light or volt meter to see if you have power there, if not check for an open somewhere or check relay and trace it down ie fuse wiring in the eng compartment or the ac switch in the truck. if you do have power at the connector turn off the truck, see if you can turn the compressor by hand, if so good if not have the compressor replaced. if you can turn the compressor the check to see if the electromagnetic clutch is working HOW?????
ok the connector on the ac compressor has 2 pins or tabs 1 is ground 1 is the + feed to the compressor , with a 12 volt test light hooked to the positive battery terminal touch each ac connector (at the compressor) with the electrical connector un plugged when the light lights up that will be the neg or ground side, now replug the connector buck on to ac unit.
now this time use a 12 volt source without the light and back probe the + POSITIVE wire this should energize the ac clutch, you should here a loud click if you do start the truck and again send 12 volts to the positive side of the compressor and see if the clutch locks up and starts running if so then only run that for 2-3 seconds that is to test the clutch,
now you need to check the freon level WITH GAUGES!!!!!!!
if it s low, add freon as if you would but youll have to energize that ac clutch to draw the freon in with a 12 volt supply at the compressor.
with the clutch running and the ac on full blast youll need to check the gauges but the low side should read from approx 28-34 , becareful wear safety glasses if your not sure have someone who does know help you you might need a manual to check the correct pressure ,

ps if you have good pressure and the system still won t go on it will probably be 1 of acouple switches high or low side switch .....

Just found this from you and try n it out. When i hook to the + side then hit the tabs on the AC Comp i cant get a ground off the top or bottom tabs. I know the light is good i tested it by just hitong a bolt on the ac comp and got a good light. How can the plug not be grouned?

 

[jimmyjamed]

The ground will be coming from the harness, not from the compressor side of the connector

 

[aryork]

2000 Ford Explorer Limited. I had same problem as the original post. First I went thru the "easy" stuff like fuzes/relay - all good.

Enough pressure had leaked out such that the pressure sensor would not allow the compressor clutch to engage and thus the compressor would not run. When the compressor doesn't run, you can't charge the system using the usual procedure.

First I removed the electrical connector to the compressor (small, 2-wire connector). Cleaned off the wires so I could see they were both not black. The white one, I guessed, was the +12V side. I got two alligator clips and clipped them on, and hooked the black to the - side of the battery terminal. Also, had to make sure two things: 1) the metal parts of the clips would not touch each other, and 2) they were out of the way of the belt.

Cranked the motor, turned A/C on max. Hooked up the coolant recharger to the low-pressure side (on passenger side). Connected the +12V wire to the battery and the clutch engaged and compressor started running. Then went and recharged the system as per the directions. All went fine.

Turned motor off. Reconnected the compressor clutch connector and was done. Thanks for all the prior posts - that gave me the confidence to do this!

BTW: this compressor is a 5-cylinder mini-engine all in itself. After seeing how it works, since I had it replaced a couple of years ago, I have a new appreciation of why you need fluid. The fluid doubles as the lubricant. This mini-engine needs lubricant just like your motor - without it you are doomed. So, keep your fluid filled!

 

[noxious]

I have the same problem on my 97 5.0 limited. I've jumped both the high side and low side safeties and it still didn't turn on. Then I jumped from the battery with the truck off to the compressor to see if the clutch works. Yep, I can hear and see it engage.

Hooked to the low side it reads in the normal range for pressure. I guess I should go ahead and jump it while running like the rest of these guys. I'll update.

 

[BrooklynBay]

Check the A/C relay.

 

[noxious]

Check the A/C relay.

There isn't a relay besides the WOT shutoff I'm aware of. I have the wiring diagram for 97.

Recharged the system with it jumped at the compressor. Cold air inside. Reconnected factory wiring. No clutch engagement.

Supplied 12v to the low pressure supply wire, purple, and the compressor kicked on.

Checked wiring diagram the purple goes to the EATC. Probed purple at the back of EATC and got no voltage with ac on.

BAD EATC?

 

[BrooklynBay]

That's what it looks like.

 

[noxious]

That's what it looks like.

Well, since I paid 800 bucks for the truck I'm not dumping more money into it. Already had to put shocks on it and remove the air ride BS.

Since the EATC still operates the blend door and what vents are being using I decided I could make it work. Besides, a mail order repair job is 50 bucks on Ebay and a replacement is 80. I had a few old switches from my nitrous days and wired one up to the purple and acc. Now I just flip the switch which went where the old air ride height selector was. Can't beat free. Even used an old lamp cord for the wires.

I do have ac gauge plenum so it does have the appropriate charge. The high side and low side switches should still operate so I feel like this crises has been averted. I live in Georgia. You need ac if you live anywhere you might get caught in traffic.

 

[JiminIowa]

Mine had the same issue but I had power to one side of the pump connector. According to my schematic, the other wire goes directly to ground, but it has very high resistance so I am going to jumper it to ground and see if the pump will cycle.