AC Condenser Cooling Fan

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brokencase
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Re: AC Condenser Cooling Fan

Post by brokencase »

My implementation is really quite simple to explain.

A new relay is placed in parallel with the existing condenser fan relay - either relay can turn on the fan.

This new relay is activated by the high side of the A/C clutch.

Note that all previous functionality is unaltered - if the three way pressure switch wants to turn on the fan in may do so.

This works if you have the two speed or single speed implementation.
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Ed Lijewski
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Re: AC Condenser Cooling Fan

Post by Ed Lijewski »

I truly appreciate your sharing of this mod in all detail.

Here's why I won't do it.

I think it will increase the cycling of the system as the de-icing switch reacts to evaporator temperatures much more often reaching the ~30*F activation point. That puts increased wear on both the de-icing switch and the a/c compressor clutch. I have a few spare used Merkur de-icing switches; they aren't easy to find anymore. The compressor uses a dry clutch so the material wears even if slowly (compared to a wet clutch) and our compressors are 30+ years old. Replacing the clutch isn't difficult and they will be available for years I'm sure but requires removal of the compressor (so we'll lose refrigerant charge, R12 in my case, unless the work is done by a shop).

In this case I'll stick with periodic cleaning of the condenser fins and periodic but less often replacement of the fan clutch.

YMMV
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Re: AC Condenser Cooling Fan

Post by brokencase »

Ed Lijewski wrote: Sun Jul 11, 2021 7:26 pm I truly appreciate your sharing of this mod in all detail.

Here's why I won't do it.

I think it will increase the cycling of the system as the de-icing switch reacts to evaporator temperatures much more often reaching the ~30*F activation point. That puts increased wear on both the de-icing switch and the a/c compressor clutch. I have a few spare used Merkur de-icing switches; they aren't easy to find anymore. The compressor uses a dry clutch so the material wears even if slowly (compared to a wet clutch) and our compressors are 30+ years old. Replacing the clutch isn't difficult and they will be available for years I'm sure but requires removal of the compressor (so we'll lose refrigerant charge, R12 in my case, unless the work is done by a shop).

In this case I'll stick with periodic cleaning of the condenser fins and periodic but less often replacement of the fan clutch.

YMMV
I observe no increasing in the cycling of the system. If you were to follow your erroneous reasoning then you come to the conclusion that the system would cycle too often at 80F ambient then it would at 100F ambient and that you should never run the A/C at 80F.

More importantly, airflow over the condenser with the car at highway speeds is probably more so that it is with the fan running with this modification in play. Are we not to drive the car at highway speeds because the compressor would cycle too often?

It is far better to avoid over heating of the condenser in high ambient temperature, especially if you have converted to R134 and/or you are stuck in traffic idling for long periods of time.

Now, are you going to continue with this argument or are you going to say "He persistently states R134 when it should be R134a?"
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Re: AC Condenser Cooling Fan

Post by brokencase »

The dual speed fan was disabled as part of the M57 rework as shown in the following attachments.
"Rewire condenser fan resistor". The resistor is bypassed and the low speed is no longer utilized.

My Scorpio has this change. Also note the "Check A/C diode continuity"
m57.jpg
m57.jpg (98.51 KiB) Viewed 2951 times
condfanm57.jpg
condfanm57.jpg (65.92 KiB) Viewed 2951 times
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Re: AC Condenser Cooling Fan

Post by john keefe »

Speaking of noise in the A/C system... It's either my fan clutch or the compressor which is rumbling pretty loud these days. I've recharged the R134, but it still puts out diddly. I know the clutch kicks on, but that doesn't mean its actually working/grabbing. Time for a new compressor?
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Re: AC Condenser Cooling Fan

Post by Ed Lijewski »

May be low on oil. I have one of these, works great.

https://www.amazon.com/TIKSCIENCE-R1234 ... 9602&psc=1

For checking oil charge level:

https://www.amazon.com/ENVIRO-SAFE-Pitt ... 6946201643

YMMV
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Re: AC Condenser Cooling Fan

Post by Ed Lijewski »

brokencase wrote: Sun Jul 11, 2021 9:08 pm
Ed Lijewski wrote: Sun Jul 11, 2021 7:26 pm I truly appreciate your sharing of this mod in all detail.

Here's why I won't do it.

I think it will increase the cycling of the system as the de-icing switch reacts to evaporator temperatures much more often reaching the ~30*F activation point. That puts increased wear on both the de-icing switch and the a/c compressor clutch. I have a few spare used Merkur de-icing switches; they aren't easy to find anymore. The compressor uses a dry clutch so the material wears even if slowly (compared to a wet clutch) and our compressors are 30+ years old. Replacing the clutch isn't difficult and they will be available for years I'm sure but requires removal of the compressor (so we'll lose refrigerant charge, R12 in my case, unless the work is done by a shop).

In this case I'll stick with periodic cleaning of the condenser fins and periodic but less often replacement of the fan clutch.

YMMV
I observe no increasing in the cycling of the system. If you were to follow your erroneous reasoning then you come to the conclusion that the system would cycle too often at 80F ambient then it would at 100F ambient and that you should never run the A/C at 80F.

More importantly, airflow over the condenser with the car at highway speeds is probably more so that it is with the fan running with this modification in play. Are we not to drive the car at highway speeds because the compressor would cycle too often?

It is far better to avoid over heating of the condenser in high ambient temperature, especially if you have converted to R134 and/or you are stuck in traffic idling for long periods of time.

Now, are you going to continue with this argument or are you going to say "He persistently states R134 when it should be R134a?"
Well, you chose R134a life, I didn't. See, your system may/does need all the help it can obtain to provide a cool, comfortable, dry ambient.

I chose to stay with R12 for my OEM R12 systems. My stash is ample enough. Condensors on Scorpios do quite well with fan clutch pulled air, getting the condenser fan boost in slow summer traffic as needed. XRs, having electric radiator fans, activate the condenser fan whenever the compressor is engaged. And XRs dealing with underhood turbo heat do need both fans on.

At highway speed there is no need for the condenser fan to run. Install a dash switch to turn it off in those situations.

If our Scorpios were younger, with less miles and less a/c use, compressor clutch wear wouldn't come to mind, but 32/33 years of service inevitably means clutch replacement likely isn't far off (certainly with climate changes).

I'm thinking ahead, for my fleet, only. (I'd be foolish to think anyone could change your mind.😄)

YMMV
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Re: AC Condenser Cooling Fan

Post by john keefe »

Thanks Ed. Did you try the pressure oil canister type (looks like a can of refrigerant refill) before deciding on that filler?
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Re: AC Condenser Cooling Fan

Post by Ed Lijewski »

John: I didn't. I have in my stash a couple of cans containing R12, oil charge (unknown quantity), dye, and leak sealer, but no more small cans of R12 compatible mineral oil.

And, in my experience, once a can of any contents under pressure is opened, it has to be used up reasonably soon or all will eventually leak out (this is using the original style needle point puncture taps).

So that's why I went the route of that injector tool. I've got a gallon minus a few ounces supply of mineral oil, the compressor my '88 was noisy (I'm sure from when I had a shop evacuate the system for a compressor manifold reseal years earlier and some oil was lost in that process), a small fleet of Merkurs, and the real likelihood of needing to add a small amount of oil charge to the other compressors, sooner or later.

Also, it was an opportunity to acquire a neat new tool!😁 And it is really neat (unscrew cap, fill to selected capacity, screw on canister to cap, connect to system, actuate compressor, and twist barrel to inject contents). It's very well made.

YMMV
Last edited by Ed Lijewski on Wed Jul 14, 2021 7:12 am, edited 1 time in total.
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Re: AC Condenser Cooling Fan

Post by john keefe »

In your experience, is it more likely that a noisy compressor w/ weak cooling output needs replacement, or just needs re-oiling? I like the idea of the oil-injector, but that could be a chunk of change that should have been put towards a new/rebuilt compressor.
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Re: AC Condenser Cooling Fan

Post by Ed Lijewski »

R134a, with same Merkur a/c parts? Have no experience with that.

Maybe buy those oil charge testers/analysers? That will help your decision making, if your oil charge is good.

Weak cooling though could be caused by several things. I wouldn't have confidence attempting a diagnosis from a distance.

Sorry for the little help.

YMMV
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Re: AC Condenser Cooling Fan

Post by john keefe »

It was converted to R134 before I got it, has the FMCo sticker. I suppose a thorough checkup on everything related to the cooling stage would help.
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Re: AC Condenser Cooling Fan

Post by Ed Lijewski »

FMCo means Ford dealer converted it? I hadn't heard of that.

It seems unlikely. R12 was still available in the 90's, after then I would assume dealerships would have declined to work on Scorpio a/cs.

EPA Regs required any R12 system converted to R134a to be so labeled prominently. Thus a sticker.

Close, but not the same as FoMoCo. Strange.

YMMV
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Re: AC Condenser Cooling Fan

Post by john keefe »

You're probably correct. Now that I think about it, it might be a Rapido kit, as it has a tall Rapido tank next to the rad
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Re: AC Condenser Cooling Fan

Post by brokencase »

I've converted to R134 and I don't notice any difference in cooling vs. R12.

On my previous Scorpio I experimented with the so called "hydrocarbon" substitute. I think it was a mixture of Propane and Ether.
It supposed to be more efficient than R12 because it is a "zeotropic refrigerant". I still have some on the shelf.

Hard to tell of any improvement in the Scorpio because the overall system is so substandard to begin with.

The only problem "hydrocarbon" substitute is it is flammable and not government approved here in the US.
However it is my understanding that Europe is fully eliminating fluorocarbons and is now transitioning to hydrocarbon based refrigerants.

The problem with the Scorpio is it does not move a sufficient volume of air through the evaporator/ducts/vents and there isn't anything you can do to really improve that. I once thought that if I could somehow install a new blower motor that spun at a faster RPM that maybe that would solve the issue. But I think all that would do is make more noise.

My new Ford Ranger is white with a black interior (like my Scorpio) and heats up just as much as the Scorpio when sitting in the hot sun.
But I get in it, put the AC on MAX and "Whoosh!" it's cool after only driving a few minutes.
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