03 Mounty AC clutch

[lilfk430]

Hi, I spent all sunday chasing this one.. Clutch not engaging. I tried jumping both hi and low side pressure switch harneses. NOTHING... in fact there is NO power to the harnesses.... i can feel and hear the relay click in the underhood fuse box when the dash AC botton is pressed.. AC worked FINE on Thurs Friday AC failed. .. we did use the cruise control on Thursday... all fuses check out... diode on the fuse box under the hood is fine.. Just no power to those switches.

thoughts?? HELP!!!

 

[TheJackal]

did you test the relay contacts in the box to see if power was getting there?

 

[lilfk430]

yes points 1 and 3 have power... i can hear and feel the relay close when the AC botton is pressed.. yet still no power at the hi and or low pressure sensor...

 

[TheJackal]

That sounds about right, try jumping the coil contacts and see if you have power at the pressure switch harnesses again. If so, the relay's coil is bad and you need a new relay.

 

[lilfk430]

thanks! little confused as to what a relay coil is.. unless u mean the coil within the realy... i can hear and feel the relay click and swapped with another one.. still no power to the sensors.. could there be something else "telling" the PCM not to engage the AC? do u know if this truck has a WOT relay.. i read some older trucks have one.. i really doubt its a wiring problem.. all started the day AFTER i used the crusie control... not sure if its related..

 

[TheJackal]

sorry about that... the night I posted that my "server" was updating and I didn't have access to the manual. At first I thought the relay was hooked directly to the switches but it's not, it goes through the PCM first...

When the high and low pressure switches are closed, they create a ground path. i don't see a WOT cut-out relay so that shouldn't be an issue.

You say you can hear the relay close... are you sure there is no power at the clutch harness?

 

[lilfk430]

thanks!! i was looing for 12v at the connectors when i guess there shouldnt be.. just a ground closed.... i do hear the relay close when the AC botton is pressed... i have NOT checked the clutch harness for 12v... in fact i cant see, of havent found the clutch connector yet... i do hear something (not the clutch engaging).. but something does happen when i close those contacts.. maybe its just a slight increase in rpm. but something does happen.... do u know where the connector is?? front,back, top or bottom on the compressor? i have been focused on looking for the 12v..havent really crawled under the truck yet..... this has been a lot of help... might end up being the clutch if i dont see 12v.. when ever i find that connector..

 

[TheJackal]

I have the V6 OHV... doesn't the Mounty have the 5.0L?

It's on the top of the compressor, on the driver's side. You can't miss it on mine, but yours sounds like a different story...

watch those fingers, too.

 

[lilfk430]

ok so bad news for me... pulled the connector off the clutch,went through the wheel well... had power at the connector... i am going to assume at this that i need a new clutch... truck only has 60k on it... oh well.. its sept 5 might wait till next year.. any idea what a job like that should cost? or will most places want to replace the entire compressor and clutch... thanks for help

 

[BrooklynBay]

Check the clutch coil with a multimeter. Sometimes it could have a bad solder connection on the connector.

 

[lilfk430]

do u know how much resistence i should see across the coil? would it be worth trying to hardware from battery to clutch points to see if the clutch engages?

 

[BrooklynBay]

You said that there was power at the connector. You could try to use a direct connnection from the battery, but 12 volts from a direct connection would still be the same 12 volts that it's already getting now.

 

[lilfk430]

happy labor day!! i went under the truck today to turn over the clutch and compressor by hand.. started the truck and the clutch engaged and all was well.. shut off the truck and clutch didnt re engage... went to re turn by hand the clutch and cant get it to start up again.. tried spraying a ton of wd40 hoping to free up what ever dirt may be in there.. any other thoughts???

 

[Carguy3J]

happy labor day!! i went under the truck today to turn over the clutch and compressor by hand.. started the truck and the clutch engaged and all was well.. shut off the truck and clutch didnt re engage... went to re turn by hand the clutch and cant get it to start up again.. tried spraying a ton of wd40 hoping to free up what ever dirt may be in there.. any other thoughts???

Ummm. why would you spray WD-40 (a lubricant) on a clutch (a/c or otherwise)? Would you use WD-40 to clean your brake pads? I would suggest using a good brake cleaner, if you want to clean the a/c clutch area.

Now, back to the original issue. Have you checked to make sure you have a proper amount of refrigerant charge? A low charge can cause erratic a/c clutch operation. Perhaps you had a small leak, that only recently caused the level to be low enough to cause a problem. Most auto parts stores, or Wal-Mart, should have an a/c recharge kit which comes with refrigerant and a gauge. You can also buy a gauge seperately. Check the pressure at the LOW side service port. The kit will come with basic generic instructions. That should give you enough to tell if the charge is low. If it is, add some refrigerant, with the truck running and the a/c on max. It may take a little bit for compressor operation to stabilize. Follow the instructions for the approx. amount to put in. .....or take it to a shop and have them check.

Another thing you can do, is jump 12v driect to the clutch wires (on the compressor, with the connector unplugged) If this engages the clutch, then you know it's good, and the problem is somewhere else in the system.

 

[lilfk430]

carguy thanks for your message i dont know why i sprayed wd40... i was thinking maybe the "brushes" or "contacts" on the clutch might be dirty and wd40 would clean that.. since i moved the compressor shaft a little and clutch engaged... i do have 12 v at the connector.. i was thinking about jumping 12 v from the battery to eliminate of confirm the connector... i will try the brake cleaner and jumping 12 v its a real bear getting to the clutch..its under the truck.. no fun thanks!!!

 

[lilfk430]

hey man i think i nailed this and want to check with you.

at the clutch connector i have 12 volts but NO GROUND>>> confirmed with multimeter...
i stripped a little insulation off the ground wire that goes to the clutch connecotor and tapped in a ground and the clutch engaged! now my question.. can i make this perm? or should the ground be sent from a sensor or the PCM ... it looks it will work with the ground jumped in but i dont want to it if will cause any harm....

let me know...

i am pretty exicted!!! at least i know the clutch is good!!!!

thanks for your help

 

[BrooklynBay]

Are you getting constant 12 volts when the A/C is switched on or all of the time (even when the A/C is switched off)?

 

[BrooklynBay]

By the way, a relay could be defective even if it clicks. The click only indicates that the coil is good, but won't tell you if the contacts are bad. You could check it two ways. The first way is to connect a test light or a meter to the output of the contacts, and see if you get voltage when you hear the click. Another way to test this is to remove the relay, and use a piece of wire to jump the connection in the socket. You could always test the relay with a booster pack, and a continuity tester if you don't want to touch any wiring inside of the vehicle.

 

[lilfk430]

... so at the clutch connector i only have 12 volts when the AC switch is turned to ON... i jumped out the ground and the clutch is engaging and the compressor is cycling... i may just leave it like this unless you think it may hurt something else. just odd to lose the ground in the first place......

 

[lilfk430]

FYI FOR EVERYONE: i left my ground jumper connected... AC has been working ever since.. i pull the low pressure connector off compressor stopped I also tested the hi side bu pulling the connector off and compressor stopped... so i am leavin it as is... thanks