A/C compressor not engaging
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Registered User
Joined: Feb 2020
Posts: 8
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From: Savannah, GA
A/C compressor not engaging
2000 Dakota 3.9 A/C compressor clutch not engaging.
I looked through the old threads and can’t find what I’m looking for so maybe someone can help me. It might be a process problem on my end. I don’t have the wiring diagram so please bare with me.
I have never seen the AC in this truck work. I got it about 6 months ago. As far as I know the lines haven’t had Freon in them the whole time. I went to set up the system and replaced the compressor and drier to be safe. I hooked it al back up but the new clutch won’t engage when I try to charge it. I’ve drawn a vacuum on the system and held it to make sure it’s not leaking. The pump I have will only hold about -15 in mercury not 30 like people recommend. But when I charge through the low port, the clutch never kicks on.
I’ve started trouble shooting and here’s what I’ve found.
1. The fuse is good.
2. I can feel the relay kick in. I’ve also tried other relays I know for a fact are working.
3. I have continuity from the fuse box to the relay input.
4. I have continuity from the relay output to the lead that goes into the compressor.
5. when volt testing I have 13 volts from the compressor to the negative battery terminal.
6. I have almost 0 (about.03v) voltage difference between the positive and negative on the compressor lead
here are my main questions:
1. Is this a bad ground?
2. does anyone know where the ground from this harness leads? I see it dive back behind the engine and lost it last night because I was working outside and it got dark.
3. Am I charging my system correctly? I see people ask what the high side is reading but how can you take a reading if you only can fill from the low side?
thanks for any feedback I can get! Sorry for any typos I am on my phone
I looked through the old threads and can’t find what I’m looking for so maybe someone can help me. It might be a process problem on my end. I don’t have the wiring diagram so please bare with me.
I have never seen the AC in this truck work. I got it about 6 months ago. As far as I know the lines haven’t had Freon in them the whole time. I went to set up the system and replaced the compressor and drier to be safe. I hooked it al back up but the new clutch won’t engage when I try to charge it. I’ve drawn a vacuum on the system and held it to make sure it’s not leaking. The pump I have will only hold about -15 in mercury not 30 like people recommend. But when I charge through the low port, the clutch never kicks on.
I’ve started trouble shooting and here’s what I’ve found.
1. The fuse is good.
2. I can feel the relay kick in. I’ve also tried other relays I know for a fact are working.
3. I have continuity from the fuse box to the relay input.
4. I have continuity from the relay output to the lead that goes into the compressor.
5. when volt testing I have 13 volts from the compressor to the negative battery terminal.
6. I have almost 0 (about.03v) voltage difference between the positive and negative on the compressor lead
here are my main questions:
1. Is this a bad ground?
2. does anyone know where the ground from this harness leads? I see it dive back behind the engine and lost it last night because I was working outside and it got dark.
3. Am I charging my system correctly? I see people ask what the high side is reading but how can you take a reading if you only can fill from the low side?
thanks for any feedback I can get! Sorry for any typos I am on my phone
Veteran
Joined: Oct 2018
Posts: 451
Likes: 64
From: Midwest
If you don't have the proper equipment you really need to have an AC pro work on this. Drawing a vacuum down to 15 isn't nearly enough to get moisture out of the system and if the system has been open for any length of time it's full of moisture. It will also never perform properly, as not drawing it down leaves regular air in the system. A proper set of gauges will connect to both the high and low sides, and will tell the condition of the system by the high and low side pressures.