Powerstroke A/C help!
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Junior User
Joined: Jan 2009
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From: Liberty, Utah
Powerstroke A/C help!
Hey guys i will post this in the other forum for these trucks but i am having problems with my a/c and need whatever help i can get! so my a/c is charged and it blows cold as ice and everything but my clutch isnt coming on. at first i could wiggle the pigtail on back of the compressor and it would kick on but now i cant ever get it to come on. i took out the shim in the clutch and still nothing. finally i took the wires off and tested them with a voltmeter and they arent getting power with the a/c awitch on or off. any ideas what to do next or how to fix it?? its like 100 degrees here all week and im dying!! thanks! 
Hotshot
Joined: Oct 2003
Posts: 17,799
Likes: 103
From: Ashland City, TN
You can jump the pins in the connector (not the pigtail) to the battery and see if your magneto engages. If it does not that way, then its bad.
Otherwise, you'll have to trace the wires on the cable to find out whats wrong.
I don't recall how it sends the signal, I don't remember any wires plugging into the climate controls in the truck. I will look later, I have a spare on the work bench.
Otherwise, you'll have to trace the wires on the cable to find out whats wrong.
I don't recall how it sends the signal, I don't remember any wires plugging into the climate controls in the truck. I will look later, I have a spare on the work bench.
Hotshot
Joined: Oct 2003
Posts: 17,799
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From: Ashland City, TN
I dont' think so. its just a coil.
I looked at my climate controls, and I remember the one in question breaking and having to switch them over. However, I still do not recall, or have a picture, of if there is a connector besides the vacuum lines.
I looked at my climate controls, and I remember the one in question breaking and having to switch them over. However, I still do not recall, or have a picture, of if there is a connector besides the vacuum lines.
Hotshot
Joined: Oct 2003
Posts: 17,799
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From: Ashland City, TN
The little one up by the clutch.
There are 2 pins in there. those control the magneto that pulls the clutch in to spin the compressor.
Thats where you should take your measurements with the volt meter if you are trying to see if its working as well.
Being an electro magnet, I'm pretty sure it doesn't matter which pin you go from pos or negaitive. Just run em to the closest battery. Thats all I did to test it.
There are 2 pins in there. those control the magneto that pulls the clutch in to spin the compressor.
Thats where you should take your measurements with the volt meter if you are trying to see if its working as well.
Being an electro magnet, I'm pretty sure it doesn't matter which pin you go from pos or negaitive. Just run em to the closest battery. Thats all I did to test it.
Posting Guru
Joined: Nov 2007
Posts: 2,158
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From: West Texas
Before you risk really screwing up the clutch eliminate the low pressure switch as the culprit. Just pull the connector off of it with teh engine running and ac switch on and jump both sides of the connector with a paper clip. That should turn the compressor on if the LP switch is bad.
If it doesn't then it's either a bad clutch or bad LP switch normally. Since you aren't seeing power at the clutch connector it probably is the LP switch. It could either be bad or a low charge causing it.
If it doesn't then it's either a bad clutch or bad LP switch normally. Since you aren't seeing power at the clutch connector it probably is the LP switch. It could either be bad or a low charge causing it.
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Hotshot
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Junior User
Joined: Jan 2009
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From: Liberty, Utah
okay so the low pressure switch is good but when i jump the magnet it turns on so i need to find out where the power comes from. does it come from the switch on the dash? all the fuses are good but no power through the wires. i followed them to the firewall. or does anybody have a wiring diagram? thanks for the help!
Hotshot
Joined: Oct 2003
Posts: 17,799
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From: Ashland City, TN
must be a switch on the blend controls.
To get that out, you take off the long trim piece that goes accross the dash.
Then under that, you will need a t-15 or whatever size socket it is 8mm i think.
That takes the bezle off. 2 screws at the top, then clips on the bottom, they break, so be careful.
Then there are 4 t-15/screws you can pull out that are the same as the other 2 to get behind the blend controls, which will only pull out so far because of the blend door cable. Just check to see if the conector is back there and if its plugged in.
I'm not sure what else could be causing a problem unless the AC clutch is vacuum operated, then you have a vacuum leak someplace.
When you have the controls on vent or floor, does the air come from where its selected, or does it come from the defrost? If it comes from defrost, then there is a big vacuum leak, if it starts on defrost for a few seconds, then eventually moves after 3 or 4 seconds, then you have a vacuum leak thats not allowing the AC to know to turn on.
I'd tear mine apart and check for you, but where the climate controls bolt in on mine, its slightly damaged, and not very easy to install or uninstall.
To get that out, you take off the long trim piece that goes accross the dash.
Then under that, you will need a t-15 or whatever size socket it is 8mm i think.
That takes the bezle off. 2 screws at the top, then clips on the bottom, they break, so be careful.
Then there are 4 t-15/screws you can pull out that are the same as the other 2 to get behind the blend controls, which will only pull out so far because of the blend door cable. Just check to see if the conector is back there and if its plugged in.
I'm not sure what else could be causing a problem unless the AC clutch is vacuum operated, then you have a vacuum leak someplace.
When you have the controls on vent or floor, does the air come from where its selected, or does it come from the defrost? If it comes from defrost, then there is a big vacuum leak, if it starts on defrost for a few seconds, then eventually moves after 3 or 4 seconds, then you have a vacuum leak thats not allowing the AC to know to turn on.
I'd tear mine apart and check for you, but where the climate controls bolt in on mine, its slightly damaged, and not very easy to install or uninstall.
Thread Starter
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Junior User
Joined: Jan 2009
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From: Liberty, Utah
i dont think there are any vacum leaks because everything works like its supposed to just the clutch dont come on but its electric not vacum operated so i will just take it apart and look or i have some extra controls i can stick on if i dont find anything
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Junior User
Joined: Jan 2009
Posts: 97
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From: Liberty, Utah
no problem thanks for all the info it was great! i am pretty mechanically inclined and will figure it out now that i know my pump and clutch are good i just havent messed with ac much and wanted to make sure thanks again
Posting Guru
Joined: Nov 2007
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From: West Texas
Wht do you mean the low pressure switch is good? If you jump the two pins on the LP switch connector and the clutch engages then you are either low on freon or the lp switch is bad. Or both. That's it. The power goes from the control head inside, to the lp switch then to the clutch. The lp switch tells the clutch sortof if it is safe to come on or not pressure wise.
Do you have a manifold gauge set for 134? If so then get the clutch engaged and look at the low pressure, suction side. If it is going below 30 then your charge is low. I'd have to write a book here to tell you all of your pressure scenarios that could happen. Cut out pressure, depending on the switch on your truck is about 20-25. Normal Low pressure is usually around 30-40 depending on the ambient temp.
Do you have a manifold gauge set for 134? If so then get the clutch engaged and look at the low pressure, suction side. If it is going below 30 then your charge is low. I'd have to write a book here to tell you all of your pressure scenarios that could happen. Cut out pressure, depending on the switch on your truck is about 20-25. Normal Low pressure is usually around 30-40 depending on the ambient temp.
