a/c compressor cycling
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New User
Joined: Nov 2000
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a/c compressor cycling
I am a new Explorer owner (97 Sport 4x4 SOHC) and new to this site, which is great by the way!
When I set the climate panel to any setting which requires the a/c compressor to run (defrost, a/c, etc.), it short cycles (1 second on- 1 second off) and the idles jumps from about 400rpm to 1000rpm while doing this. My first thought was low on freon, so I disconnected the low pressure switch and shorted out the connector pins, but compressor still short cycles. Next I swapped the WOT a/c relay in the fuse box with another one like it, still no help. What else sends a signal to the clutch for engaging/disengaging? When the truck is at idle with any settings on the panel where the compressor isn't supposed to run then it idles smooth. I've only had the truck for 6 weeks and I just got it out of the shop (2 weeks ago) for the dreaded camshaft tensioners and the intake gaskets were replaced as part of that repair. Has anybody figured out what is causing this?
I really like the Explorer and I live in Louisville where they are made. I was hoping to help the local economy by buying one (the assembly plant, not the service department), but when do the repairs stop on this thing??
thanx
Dale
When I set the climate panel to any setting which requires the a/c compressor to run (defrost, a/c, etc.), it short cycles (1 second on- 1 second off) and the idles jumps from about 400rpm to 1000rpm while doing this. My first thought was low on freon, so I disconnected the low pressure switch and shorted out the connector pins, but compressor still short cycles. Next I swapped the WOT a/c relay in the fuse box with another one like it, still no help. What else sends a signal to the clutch for engaging/disengaging? When the truck is at idle with any settings on the panel where the compressor isn't supposed to run then it idles smooth. I've only had the truck for 6 weeks and I just got it out of the shop (2 weeks ago) for the dreaded camshaft tensioners and the intake gaskets were replaced as part of that repair. Has anybody figured out what is causing this?
I really like the Explorer and I live in Louisville where they are made. I was hoping to help the local economy by buying one (the assembly plant, not the service department), but when do the repairs stop on this thing??
thanx
Dale
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New User
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a/c compressor cycling
> You need to have the
>system checked to make sure
>it has the proper amount
>of R134A . You cant
>diagnose any problems other than
>the obvious if the system
>is low on R134A .
>
Thanks for the reply Paul!
If I shorted the connector for the low pressure switch for the freon level, wouldn't that bypass any low freon condition and cause the compressor to stay engaged? I have tried that and the compressor still short cycles. The WOT relay also opens and closes with each cycle, so I feel that something electrical is telling the clutch to turn off and on. Is there some other switch or solenoid that sends the clutch a signal?
Thanks again,
Dale
>system checked to make sure
>it has the proper amount
>of R134A . You cant
>diagnose any problems other than
>the obvious if the system
>is low on R134A .
>
Thanks for the reply Paul!
If I shorted the connector for the low pressure switch for the freon level, wouldn't that bypass any low freon condition and cause the compressor to stay engaged? I have tried that and the compressor still short cycles. The WOT relay also opens and closes with each cycle, so I feel that something electrical is telling the clutch to turn off and on. Is there some other switch or solenoid that sends the clutch a signal?
Thanks again,
Dale
Postmaster
Joined: Jul 1999
Posts: 3,172
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a/c compressor cycling
Im not really familiar with the A/C system on your Explorer , but I think the system also works with a temp sensor that reads the outside ambient temp ? A great site for A/c related things is http://www.aircondition.com . There are a couple of A/c techs there that really know their stuff .
Posting Guru
Joined: Jan 2001
Posts: 1,124
Likes: 1
From: Rural Florida Panhandle
a/c compressor cycling
I don't know the location, but there is also a hi pressure switch. By law, the r134 systems are supposed to shut off with high pressure just like low pressure (to prevent venting to atmosphere).
I would definitely get a set of gauges and check the pressures before spending any time or money otherwise. Or have an a/c technician do it for you.
Winford
I would definitely get a set of gauges and check the pressures before spending any time or money otherwise. Or have an a/c technician do it for you.
Winford
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a/c compressor cycling
Well I have tried numerous things and now only have the problem very rarely.
I believe it was related to a low freon condition, I have recharged the system and really dont see the problem much at all anymore.
Some other things I have tried that seemed to also help was clean the IAC, Throttle Body and MAS sensor. Everytime I would clean these the problem would go away also, so I'm not real confident on what actually caused it. I would suggest cheking your freon level first, preferably with guages so that you can be accurate, and you may want to clean the above listed components, that also seemed to help.
Dale
I believe it was related to a low freon condition, I have recharged the system and really dont see the problem much at all anymore.
Some other things I have tried that seemed to also help was clean the IAC, Throttle Body and MAS sensor. Everytime I would clean these the problem would go away also, so I'm not real confident on what actually caused it. I would suggest cheking your freon level first, preferably with guages so that you can be accurate, and you may want to clean the above listed components, that also seemed to help.
Dale
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New User
Joined: Jun 2002
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a/c compressor cycling
You've said the WOT relay cycles. I believe the electrical path for the AC clutch feed is that the control from the dash feeds the pressure switch, then it goes through the WOT relay to the AC clutch.
Your computer is cycling the AC clutch ( you can verify this by removing the WOT relay and shorting the NO contacts). Unless the Computer is getting a pressure signal from the AC system and shutting you down for High pressure, then High pressure cutout isn't your problem.
I would be trying to find out if the computer is getting a signal which makes it think you have a WOT condition.
Your computer is cycling the AC clutch ( you can verify this by removing the WOT relay and shorting the NO contacts). Unless the Computer is getting a pressure signal from the AC system and shutting you down for High pressure, then High pressure cutout isn't your problem.
I would be trying to find out if the computer is getting a signal which makes it think you have a WOT condition.
Senior User
Joined: Aug 2001
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From: peekskill'ny
a/c compressor cycling
also engine temp will cause ac to drop out.but its normal for ac to cycle on and off every 10-15 seconds or so on all 98+ in any selector position except the vent position and off
