Model: Town & Country
Engine Size: 3.3
Refrigerant Type: R134a
Ambient Temp: 90
Country of Origin: United States
I replaced the a/c compressor on our 2003 T&C recently. It was a new comp. not a reman. I also replaced the dryer and expansion valve with new o-rings. R134a system of course.
This was due a locked up clutch on the factor original comp with close to 180k miles. The compressor itself did not fail just the clutch. The oil that came out of the original compressor was as clear as brand new oil with no visible contaminants. I cost of a clutch alone was close to the cost of a reman compressor so I decided to go that route (long story after that but company took 3 weeks and 3 promises to send out my reman compressor so after calling to complain AGAIN and ask for a refund, they sent me a brand new comp. for the same cost since they could never get my reman in stock.)
Anyway.... it's been a few weeks since it was installed and I had to drive the van but the compressor was full of factory oil and I never attempted to even engage the compressor until I could get the system vacuumed.
Last night I have vacuumed down to 29 microns (or what the measurement is called), turned pump off and even after over night the vacuum held according to the manifold gauges. So I attempted to put in the first can of R134a (using synthetic Arctic Freeze). Because of the vacuum, I could hear a suction for a moment and could tell a small amount of coolant went in (low side), but with engine running and a/c button engaged, the compressor never started cycling to pull the rest in.
So more research, I see this is fairly normally since the system was vacuumed and had no coolant at all left in the system. I've read suggestions to try and put in a can upside down on the high side as they do in the factory to get enough in the system so the low pressure cut off would allow the clutch to start cycling.
Another option is to jump the low pressure cut off to force the clutch to engage.
Well, I don't have the right hose nor know how to force a can in liquid state in the high side so I have attempted to jump the low pressure cut off switch.
I'm running into conflicting information. Some sites say that these vans don't have low pressure switches and you have to jump the a/c relay on the power distribution box. Some sites say that the switch next to the dryer is indeed a low pressure cut off and to jump it.
Apparently I'm not jumping something correctly as I can't force the clutch to engage.
Can someone offer insight as to what wires or terminals exactly to jump to force the clutch to engage?
If jumping the a/c relay do you leave the relay in place (slightly raised to access the prongs) or pull it? I've read to jump point 30 and 87a but 87a makes no connection on the box.
Frustrated and hot.
Don't try to jump it. Get the pressure up and the compressor will start. If not, find out why. Seized / burnt out clutch is likely to blow the fuse. Or your new compressor is a dud. A lot of them come from, umm wherever they come from, with the clutch gap too wide.
How did you vacuum without connecting to the high side? Realize that the shrader valves are not designed to hold vacuum. You have to leave the same hose connected to the port the whole time the system is under vacuum or air is likely to leak in. After a vacuum leakup test, you should pull vacuum again for about 15 or 30 minutes to pull out any water etc that outgassed during the test period. Then charge immediately into the vacuum.
I used Mastercool a/c manifold gauges that I borrowed from Auto Zone. I have a 3cfm 2-stage vacuum pump.
On the manifold gauges, the red hose is hooked to the high side with quick connect, the blue hose is hooked to the low side with quick connect.
I ran the vacuum process a few times, hoping that the vacuum would 'suck' the coolant in when I first open the valves. And some does go in but apparently not enough to get the clutch working.
Each time, I have pulled the vacuum to 29" according to the manifold low gauge for at least 30 minutes. One time was at least 45 minutes. I have the high and low gauges open during the time the vacuum is pulling.
I close the high side and leave everything attached with the pump off. After several minutes (once over night) I checked and the vacuum is still holding.
Then I close both valves, remove the yellow hose from the pump and connect to the can tap, with R134a attached. I start the van, with a/c switch on and fan on high, I punctured the can, then opened the can tap valve, then opened the blue lowside valve.
I have no way of knowing an exact amount, but I fairly decent guess, is about 10-20% of the can gets pulled into the system and the pressure on the low gauge goes to around 70 every time. As I agitate the can, pressure will go up and down a little and has risen to around 90 and then it will take no more coolant and the clutch never kicks on.
I have revved the engine with the throttle cable under the hood during more of the above and it makes no difference.
So the clutch could be bad? Isn't the only way to tell if it's a bad clutch, is to jump the switch or relay or whatever is needed to be done, to see if it kicks on?
All artic freeze synthetic refrigerants have leak sealer in them,they may say system safe,but its not.
I think I found out exactly how to force the clutch to engage.
I pulled the a/c relay, inserted a jumper wire between where 30 and 87 would be if the relay was inserted.
Started engine, turned on a/c...... clutch not engaging
I wish I hadn't done it, but due to forced circumstances, I had to start using the van as soon the compressor and other components were installed without charging it. But as originally mentioned, the a/c was never attempted to be used nor the defrost (which temps were high enough that hadn't been needed anyway). In addition, the low pressure should have kept from attempting to engage. Could this have damaged the compressor? Wouldn't the clutch still click or do something or cause a drag on the system anyway?
I hope it's just another relay/switch or loose power connection somewhere.
What should I check next please?
Do not run the compressor without a decent charge of refrigerant. Buy some plain R-134a without additives and dump a couple of cans in as liquid into vacuum with the engine off. This will build enough pressure that the switch will close and the compressor should start.
So with the relay jumped, the clutch still did not engage? Have you checked the fuse? You should start measuring voltages rather than jumping parts. On some cars (mostly GM) the PCM will lock out the compressor but jumping the relay would have bypassed that.
I'll point out again, #1: burnt up clutch is likely to short circuit and blow the fuse. #2: the only electrical part you've replaced is the compressor so that's the prime suspect for an electrical problem.
Edited: Sun June 05, 2011 at 9:34 AM by mk378
From what I can see, the only fuse is the 15a fuse under the hood in the power distribution box (as it's called). Is that right? I have visually checked it and it looks good. I will check it again with a meter.
I can't find my meter, so using a simple test light....
15a a/c fuse under the hood is good.
I get power to pins 30 and 85 when the key is on.
I unplugged the 2 wire harness connection from the compressor and checked each wire, while jumping the relay (pin 30 and 87) with key just to ON, engine not running, no power to either wire going to the compressor.
left jumper in place, started engine, pressed a/c button, still getting power to pins 30 and 85 (and also 87 now of course since it's jumpered.... still power at a/c fuse. no power at either wire going to compressor.
so i lose power somewhere from the a/c relay to the 2 wire compressor connector.
I don't see any place where a wire could have gotten broke while replacing the compressor. but power to the compressor did work before replacing it.
what else should I check?
what colors are the two wires inside the harness for the compressor? do the same two colors stay the same from the power center to the plug?
Well, it's fixed. compressor is running. dumb cause, almost too embarrassed to say what it was.
The power connection to the compressor. I had already pressed it together to ensure it was seated firmly, but unplugging it to do some tests and then plugging it back up, for what ever reason, made it work now. I hope it just wasn't seated properly and not a loose connection that is only working for now. But at least I know where to look if it stops again.
And I know where to look at FIRST, next time I'm in a similar situation
Thank you all for your help. It really did help.
Just one comment on your technique when disconnecting the vacuum pump and connecting the can of 134a. After you disconnect the yellow from the vacuum pump, you pull into the yellow hose a complete fill of room temperature air. To purge that, you could connect the 134a can to the yellow hose, and purge it at the gauge set so that you would have only possible the miniscule portion of air between the valve seat and the inlet port of the gauge.
Another way to prevent that, and NickD would likely tell you how better, is to Tee into the yellow, so that all the yellow 'supply' has been put under vacuum with no chance of ingesting any air.
simplificate and add lightness
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