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A few ac questions.

NevurMind85

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June 7, 2014
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City, State
Floyds Knobs Indiana
Year, Model & Trim Level
96 explorer limited
So my wifes 96 4.0 ohv blew the ac last year while she was driving up from the highway, she says it stopped blowing cold and she could smell freon and could hear it leak. Under visual inspection i noticed the accumulator dryer has rusted. Last weekend after having bought one, i i figured id check with my guages and it was sitting at 100psi, which suprisurp me. I can't figure out now what would have blown (haven't done a uv test yet) and how its still holding pressure. My other downside is when i took my guages off, the highside started spraying and wouldn't stop so i guess I get to replace that now. Any ideas? Do i swap on the new accumulator dryer and see ewha happens or was it the high side port like some people have had issues with?
 



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I never go by what a non-automotive person (in this case your wife) tells me. It will lead you down the wrong path every time. Verify the issue yourself. As your system is apparently still holding pressure, it doesn't sound like you had a refrigerant leak.

Have you tried jumping the A/C clutch to see if the system works? You might just have a small leak and the low pressure switch is preventing the system from working or the high pressure switch might be stuck. Jumping the A/C clutch will bypass both switches.

As far as your high pressure port leaking, you'll need to replace the schrader valve (looks like a tire valve) if you can't get it to stop leaking. Auto parts stores sell a tool to R&R the valve (looks like a tire valve tool, but longer).
 






Make sure the wife actually knows what R-134a smells like. I have no idea, having never smelled it myself, but the google says it has almost no smell at all.

I would ask her to describe the smell. I bet she'll say "syrupy" or "sweet," which indicates antifreeze.
 






No i haven't tried jumping it yet. Ill check all the fuzes and relays after work today. The compressor does turn by hand which is good
 






I did jump the clutch with the truck off, tried jumping the high and low switches. The clutch is good (i know jumping it with the clutch off doesn't help anything other than eliminate the clutch itself, i ran out of time before it started raining). Couldn't get it to do anything jumping the pressure switches and the fuse wnd relay are good
 






Not sure what you mean by "with truck off". Engine off? Key off? With the engine or key off I wouldn't expect the high & low pressure switches to do anything if jumped. The magnetic clutch might click/engage if jumped straight to the + terminal of the battery.

Do you have the automatic climate controls (EATC)? I would assume the Limited would. If you do, there's a component inside of the module that breaks a solder joint on a relay or something that controls the A/C compressor. A few people here have reported this problem an managed to fix the issue by re-soldering the joint.
 






Hmmm yes it has the eatc, ill have to check into that. I tried jumping the switches with the truck running and tried the clutch with the engine off and the keys out, jumpes it straight to the battery. Clutch still works. Im gonna go buta new high pressure valve and make sure it just didnt leak and was too low on running pressure to trigger the system.
 






Ok ive pulled the eatc and had a burnt connection. Reflowed that. Now i have power to both high and low pressure switched and nothing to the clutch. I jumped the clutch to the battery with guages on the system and it has enough to run the system, at least enough it should cycle the system. I checked the low pressure switch, the connector gets 12v like it should but when i run an resistance test across the switch itself i get 0 ohm's. So im thinking at least the low pressure switch is bad maybe the high. Or is there a safety switch somewhere in the dash or blower box that im missing?
 






Ok ive pulled the eatc and had a burnt connection. Reflowed that. Now i have power to both high and low pressure switched and nothing to the clutch. I jumped the clutch to the battery with guages on the system and it has enough to run the system, at least enough it should cycle the system. I checked the low pressure switch, the connector gets 12v like it should but when i run an resistance test across the switch itself i get 0 ohm's. So im thinking at least the low pressure switch is bad maybe the high. Or is there a safety switch somewhere in the dash or blower box that im missing?

The HIGH and LOW pressure switches are the system "safety". Seems awfully coincidental that you'd have a bad solder joint and a bad switch as the same time. Are you sure you have enough refrigerant in the system? Have you tried jumping the LOW pressure switch? IDK of the system expects to see an open or closed LOW pressure switch in order for the compressor to run.
 






Even with low pressure it should cycle some. And I would assume it would want the switches closed to pass some power on. And no i forgot to jump the switches.
 






Even with low pressure it should cycle some. And I would assume it would want the switches closed to pass some power on. And no i forgot to jump the switches.

The low pressure switch stops power to the AC clutch when the freon is low(pressure is too low), high pressure switch does the same for too much pressure.

With some freon lost, the LP switch is probably stopping current from reaching the AC clutch. You can jump the LP switch and confirm it's okay, but it sounds like you just need more freon, and possibly a vacuum done depending on how long it's been(if over years some moisture or air has gotten inside). If you R&R the schrader valve, or the dryer etc, it will need evacuating with a vacuum pump.
 






Alright. Here goes. Im currently in the driveway with a set of guages on, have a long jumper wire with gator clips going from the battery to the power-in side of the low pressure switch and a short one going to the send side of the pressure switch connector. My freon pressures are currently 34 low and roughly 210 high and its currently 80°f outside. The power running through the switch and back through the system currently has the clutch on and the system running and a nice 38-40°f coming out of the middle vent. I did try jumping the low pressure switch to no avail. I have eliminated the pressure switch as a problem. When i hook my dvom into the wiring clip for the low pressure switch im getting fluctuating voltage, itll jumping to its 14 volts but then it drops back to nothing then back up and it might hit 10v but after the first initial contact and it jumps and drops from 14v it doesn't really go back and its never steady. Any ideas? Think its just a short somewhere or is it another issue like the eatc?
 






And the high pressure port cap holds pressure on it enough to keep the system stabil and I will change the port after i get this figured out so I don't have to do a bunch of stupid stuff to get the system to draw in freon. And yes i already know how to vacuum down and fill a system just never had to troubleshoot wiring issues before.
 






So when you hot wire power to the input of the low pressure switch, your AC clutch runs as it should?


I'm not sure, but I thought all of the late 90's EATC modules ran low current out and fed a relay to power the AC clutch. That might be the issue. Early AC control head units run full current through them, so the wiring or relay in that is likely to fail over time.

My old 91 Lincoln EATC stopped producing enough current to power the AC clutch, and I figured it out without repairing the EATC.

If the 96 EATC just puts out a low current signal and a relay powers the AC clutch, then work on that relay power circuit. If the 96 EATC still puts out high current(no relay between it and the clutch(not the AC cut out relay, that's different)), then either fix the EATC, or do what I did. I added a simple relay near the battery and AC clutch, used the stock clutch wiring nearby, to trigger the new relay. My Lincoln's EATC works fine to trigger the new extra relay, and that runs the compressor.
 






Hmm not a bad idea to add a relay. I might just have to do that
 






So my wifes 96 4.0 ohv blew the ac last year while she was driving up from the highway, she says it stopped blowing cold and she could smell freon and could hear it leak. Under visual inspection i noticed the accumulator dryer has rusted. Last weekend after having bought one, i i figured id check with my guages and it was sitting at 100psi, which suprisurp me. I can't figure out now what would have blown (haven't done a uv test yet) and how its still holding pressure. My other downside is when i took my guages off, the highside started spraying and wouldn't stop so i guess I get to replace that now. Any ideas? Do i swap on the new accumulator dryer and see ewha happens or was it the high side port like some people have had issues with?
The one thing no one mentioned is the pressure relief valve in the compressor...If your high side pressure gets too high it will open to reduce the pressure in the system and then close to protect what is left...Your system is running near the top end pressure-wise at 210 psi @ 80 F... I would look at the fan clutch, the condenser and radiator fins, or an overcharge in the system...If the system "blew" refrigerant and you lost refrigerant from the high side and didn't add more back and the system is running at these pressures you were grossly overfilled...But you really want to drop the pressures from what they are running now or that pressure relief valve might open up again...For 80 F your high side pressure range will be 184-216 psi and you will see that pressure increase as the temperature goes up...To see if the fan is cooling the condenser well use a garden hose to spray water into the condenser/radiator fins and watch the high side pressure drop...If the pressure drop is more than about 30-40 psi you have heat that your fan is not removing and probably have a weak fan clutch or problems with the fan blade...You should be seeing a high side pressure range based on the formula of 2.3-2.7 x ambient temp at the condenser...
 






Anyone have a wiring diagram for a 96 explorer ac system?
 






Free wiring diagrams are available here in the automotive repair section.

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Thank you so very much for help on the wiring diagrams. I pulled the eatc back out but still hooked up and started the truck and tested power out of the purple wire that feeds power to the low pressure switch and found its feeding the low and jumping voltage out of the eatc. I did read that the red wire coming from the guage cluster to the eatc can cause an issue like this so ill need to get back in there and test that. To double check the low voltage i did feed the purple wire 12v from the power outlet/cig lighter and it kicked on the compressor so at least I know its not the wiring in the engine bay.
 



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