Max a/c vs regular a/c setting
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Senior User
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From: Bethel Park, PA
Max a/c vs regular a/c setting
I know that the difference between the two is that the regular a/c setting uses outside air and max a/c recirculates the air from the cabin. I've had an issue with my a/c compressor shutting off when I have to floor the gas and sometimes it shuts off on its own during certain situations while driving normal. Would this issue possibly go away if I keep the setting on max all the time? I would think that there would be less of a load on the compressor since you're recirculating cold air from the cabin instead of relying on hot outside air to cool things in the cabin. Am I right on this or is there more to it than that? Thanks.
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Senior User
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From: Bethel Park, PA
Thanks for the advice. You're right about it not making any difference. I was sitting at a light earlier tonight and the a/c shut off on me and I had it set to Max A/C. A few minutes later I turned it off and turned it back on and it worked the rest of my drive home. I went over to the HVAC forum and it talked about possibly needing to remove a shim if my clutch is slipping. How do I do that? There's a center bolt on the clutch plate. Do I just loosen that to take the plate off or is it more complicated than that? Knowing my luck, it's probably more complicated. lol Would tightening that same bolt help close the gap? Thanks.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
It's just that easy. Check the gap first, though.
Slip a business card about 1/4" into the gap. If it falls out, the gap is too wide. Remove the bolt, slip the clutch plate off, watching for falling shim washers. Remove one shim from the clutch plate bore(maybe the only one) and reinstall the plate.
This "usually" closes the gap just enough that the clutch and pulley don't rub with the compressor is off. If it rubs after removing the shim, you'll need to get a shim kit from Ford and actually set gap to .020" or less.
Slip a business card about 1/4" into the gap. If it falls out, the gap is too wide. Remove the bolt, slip the clutch plate off, watching for falling shim washers. Remove one shim from the clutch plate bore(maybe the only one) and reinstall the plate.
This "usually" closes the gap just enough that the clutch and pulley don't rub with the compressor is off. If it rubs after removing the shim, you'll need to get a shim kit from Ford and actually set gap to .020" or less.
Thread Starter
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Senior User
Joined: Jun 2008
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From: Bethel Park, PA
It's just that easy. Check the gap first, though.
Slip a business card about 1/4" into the gap. If it falls out, the gap is too wide. Remove the bolt, slip the clutch plate off, watching for falling shim washers. Remove one shim from the clutch plate bore(maybe the only one) and reinstall the plate.
This "usually" closes the gap just enough that the clutch and pulley don't rub with the compressor is off. If it rubs after removing the shim, you'll need to get a shim kit from Ford and actually set gap to .020" or less.
Slip a business card about 1/4" into the gap. If it falls out, the gap is too wide. Remove the bolt, slip the clutch plate off, watching for falling shim washers. Remove one shim from the clutch plate bore(maybe the only one) and reinstall the plate.
This "usually" closes the gap just enough that the clutch and pulley don't rub with the compressor is off. If it rubs after removing the shim, you'll need to get a shim kit from Ford and actually set gap to .020" or less.
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
Likes: 5
From: Lorain County, Ohio
I checked the refrigerant level and I'm good with that.
How did you do that?
It could also be that there is an airflow issue over the condenser (bad fan clutch, debris, etc). That would make it cycle on the High Pressure Cutout switch. You would need to monitor the high side pressure to find out.
Check the clutch gap first. Then go from there.
How did you do that?
It could also be that there is an airflow issue over the condenser (bad fan clutch, debris, etc). That would make it cycle on the High Pressure Cutout switch. You would need to monitor the high side pressure to find out.
Check the clutch gap first. Then go from there.
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From: SW Va
On the A/C shutting off, I like the high side pressure idea.
Seeing as how it's bug season, if you have lots of bugs in your area & don't use a bug screen, or haven't cleaned the condeser lately, maybe have a look up front, for bugs, leaves, mud, or a plastic bag covering the condenser & restricting air flow.
If that doesn't pan out, check the fan clutch, it may not be working at idle, to pull enough air through the condenser & radiator.
A clue may be, does the engine coolant temp gauge climb when setting at a long light????, If so, put the fan clutch on your suspect list too.
More thoughts for your suspect list, let us know what you find
Seeing as how it's bug season, if you have lots of bugs in your area & don't use a bug screen, or haven't cleaned the condeser lately, maybe have a look up front, for bugs, leaves, mud, or a plastic bag covering the condenser & restricting air flow.
If that doesn't pan out, check the fan clutch, it may not be working at idle, to pull enough air through the condenser & radiator.
A clue may be, does the engine coolant temp gauge climb when setting at a long light????, If so, put the fan clutch on your suspect list too.
More thoughts for your suspect list, let us know what you find
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Senior User
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From: Bethel Park, PA
I have a question. I tried to loosen the bolt in the center of the clutch on the compressor but the clutch plate just turns with it. Do I need to somehow clamp down the clutch plate so I can get the bolt loose?
As far as the other suggestions go, I took a look at the condensor and I don't see any debris in it. The fan runs at idle and my temp gauge doesn't go up at idle. It's weird because it can randomly just shut off and it also can work just fine for long periods of time. This morning it shut off just parked in a parking lot. The rest of the day so far it's worked fine. I noticed this morning when it shut off the fan was on the low setting. When I've had it on the high setting it hasn't shut off so far today. That may just be a coincidence, I don't know. Trying to figure out what is making it shut off is driving me nuts since it seems so random.
Anyway, any advice concerning how to get the clutch plate off would be appreciated. Thanks!
As far as the other suggestions go, I took a look at the condensor and I don't see any debris in it. The fan runs at idle and my temp gauge doesn't go up at idle. It's weird because it can randomly just shut off and it also can work just fine for long periods of time. This morning it shut off just parked in a parking lot. The rest of the day so far it's worked fine. I noticed this morning when it shut off the fan was on the low setting. When I've had it on the high setting it hasn't shut off so far today. That may just be a coincidence, I don't know. Trying to figure out what is making it shut off is driving me nuts since it seems so random.
Anyway, any advice concerning how to get the clutch plate off would be appreciated. Thanks!
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Joined: Jan 2004
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From: SW Va
OK, good feedback on the condenser & fan.
The in cabin low speed fan setting notation may be a clue, if you live where it's really hot & humid, as the evaporator may be freezing up from lack of sufficient air flow through it,, such that it freezes up & restricts air flow & that can cause high side compressor pressure to rise & the high side pressure switch to turn the compressor off, so it isn't damaged.
Then after the pressure drops, it'll reset & allow the compressor to run again until it again rises to the cut off point.
If running the fan at meduim or high speed eliminates the compressor turning off for long periods,, that may be the problem.
Are you certain the system isn't over charged???? It should be evacuated & then charged by the specified refrigerant weight & the low & high side pressure should then be within specs.
If all that checks out, maybe the high side pressure switch is acting out, or maybe a piece of trash is plugging an internal orifice & causing mischief???
More thoughts for pondering.
Let us kow what you find.
The in cabin low speed fan setting notation may be a clue, if you live where it's really hot & humid, as the evaporator may be freezing up from lack of sufficient air flow through it,, such that it freezes up & restricts air flow & that can cause high side compressor pressure to rise & the high side pressure switch to turn the compressor off, so it isn't damaged.
Then after the pressure drops, it'll reset & allow the compressor to run again until it again rises to the cut off point.
If running the fan at meduim or high speed eliminates the compressor turning off for long periods,, that may be the problem.
Are you certain the system isn't over charged???? It should be evacuated & then charged by the specified refrigerant weight & the low & high side pressure should then be within specs.
If all that checks out, maybe the high side pressure switch is acting out, or maybe a piece of trash is plugging an internal orifice & causing mischief???
More thoughts for pondering.
Let us kow what you find.
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Senior User
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From: Bethel Park, PA
Just something else to throw out there for now, is it possible that my compressor just could be going? It is an old truck with the original compressor. I took my truck to a mechanic last year concerning this and as soon as he heard the compressor kick on he said the compressor sounded like it was going bad. Now, I'm pretty sure that compressor has always been pretty noisy anyway so I'm not sure. I want to at least try and take a shim out first and see if that makes a difference or not, once I figure out how to get the clutch plate off of course. If that doesn't change anything then I'll go from there. Even though it shuts off randomly sometimes, it still almost always shuts off when I have to hit the gas pretty hard.
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Senior User
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From: Bethel Park, PA
Yeah I know but it's not supposed to completely be shut off for a while after that is it? When my ac used to operate normally, when I'd go to WOT the air would get slightly warmer while flooring it but go right back to being ice cold after. Now, when I floor it the compressor shuts off and I get warm air through the vents for a while. Sometimese turning the ac off and on a few times gets it cold again. I was just sitting in a parking lot eating for a good while with my ac blasting and it was ice cold the entire time. When I pulled out of the lot it eventually shut off and blew warm air again for a bit. When I pulled up to a light for a minute it got cold again. I didn't floor at all through any of this. Probably didn't go any faster than 30mph. Sometimes it shuts off and sometimes it's fine.
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From: SW Va
Are you certain the compressor is turning off???? Is it such that you don't feel the compressor cycling on & off when it doesn't seem to be cooling????
The reason I ask is, the conditions when you say it seems to not be cooling, is when engine vacuum is low, ie when your acceleratng, so if you have a vacuum leak in the hvac control, maybe the blend door is opening & bleeding in air from the heater & causing you to think the AC has turned off, then when you reach cruising speed, or coast to a stop at a light, engine vacuum goes back up because the throttle is closed or nearly so & the blend door closes & you get only cool air from the A/C????
More thoughts to ponder. lol
We could speculate all day on this, so
maybe just consider taking the danged thing to a known good Ford A/C specialist & let them unravel the mystery????!!!!
The reason I ask is, the conditions when you say it seems to not be cooling, is when engine vacuum is low, ie when your acceleratng, so if you have a vacuum leak in the hvac control, maybe the blend door is opening & bleeding in air from the heater & causing you to think the AC has turned off, then when you reach cruising speed, or coast to a stop at a light, engine vacuum goes back up because the throttle is closed or nearly so & the blend door closes & you get only cool air from the A/C????
More thoughts to ponder. lol
We could speculate all day on this, so
maybe just consider taking the danged thing to a known good Ford A/C specialist & let them unravel the mystery????!!!!
Fleet Mechanic
Joined: Feb 2006
Posts: 1,776
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From: Lorain County, Ohio
If there is debris in the condenser you may not be able to see it. It collects in between the condenser and radiator.
A High or Low pressure issue can only be diagnosed by looking at the pressures. Check the clutch gap FIRST. If that's not the problem, you'll need to monitor the pressures.
You can hold the clutch plate by clamping across the pulley with a pair of channel locks. Don't take it apart until you know for sure the gap is too wide. One step at a time.
A High or Low pressure issue can only be diagnosed by looking at the pressures. Check the clutch gap FIRST. If that's not the problem, you'll need to monitor the pressures.
You can hold the clutch plate by clamping across the pulley with a pair of channel locks. Don't take it apart until you know for sure the gap is too wide. One step at a time.
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