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Misting the Condenser as Needed

Minx on Wed March 11, 2009 2:28 PM User is offlineView users profile

Year: 1993
Make: Ford
Model: Explorer
Engine Size: V-6
Refrigerant Type: 134

I'm ready to experiment with automatically misting my condenser, as all other efforts (cleaning, new heavy-duty fan clutch, new 10-blade fan) have failed to improve the airflow enough to get the clutch cycling at idle -- and vent temps below about 50. (I have the more-efficient condenser design, BTW.)

I'm thinking of a tank of distilled water feeding a windshield-washer pump and sprayer, triggered by a pressure switch on the high side. The switch would be set to kick on about 250 psi.

I think I an adjustable switch like that online once, but can't locate it now.

Have any of you tried something like this?

HECAT on Thu March 12, 2009 5:57 AM User is offline

Have any of you tried something like this? Only as a test, not as a fix.

I am sorry if I have missed or not followed a previous post on this topic, but...

Does spraying water on the condenser at idle fix your problem? Does the high side pressure drop, compressor cycle, and vent temps become much cooler? Does it cool well at speed? Can the now repaired/improved air flow suck a rag to the condenser? If you changed to a new condenser design, did the charge amount need to change?



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NickD on Thu March 12, 2009 10:07 AM User is offline

R-12 system with an R-134a retro, always more problems with Fords for some reason, for awhile, even Ford was offering a kit. But not easy to offer suggestions until you post low and high pressures at the ambient temperatures and both at idle and at 1,500 engine RPM. Orifice and the cycling switch also have to be played with, but have to know where you are at. Sticking with R-12 is yet another solution.

iceman2555 on Thu March 12, 2009 10:38 AM User is offlineView users profile

Guess, I am just an old skeptic...but WHY go to this trouble.
As stated, pressures and test conditions would be nice to have. But seems as if the system has not been serviced properly. Many of these late model units were already set up for 134a (condensers/hoses/etc). This was one of the 'easier' units to retro.
First aspect would be to know if the system was totally cleaned prior to adding the new lube and refrigerant? Was the system flushed and if so, what type flush was used? If not the system may have a serious abundance of lubricant within the system.
How as the system recharged? A calibrated machine or simply adding refrigerant by the can and relying on pressures to determine if the system is totally recharged? If the latter scenario is the case, my thoughts go to a undercharged system. If this is the case, the balance of refrigerant to temp may be such that the LPCO will never cycle the compressor...nor will the vehicle cool properly.
Instead of using pressures (not always a valid procedure) try measuring temps at certain locations.
Place the vehicle in this condition, MAX COOL, HIGH BLOWER, DOORS OPEN, ENGINE @ IDLE. Let the system stabilize, this takes about 5-7 minutes. Determine the temperature of the evaporator inlet (cool side of the orifice), determine the temp of the evap outlet (prior to the accumulator). These temps should (ideally) the same. These temps may vary....3-5 degrees, but should be the same. When this condition is met, the system if fully charged....NO MATTER WHAT THE HIGH SIDE PRESSURES INDICATE (no yelling....emphasis only). If a high side pressure problem exist...it must be addressed...do not remove refrigerant....address the cooling issue. It is doubtful that the system will experience a high side pressure problem...esp with the changes to the engine cooling system.
Completely evaluate the system under these conditions....the LPCO will not cycle during this test
Once the recharge is complete....close the doors...elevate engine speed....max cool....lower blower speed and then allow the system to cool the vehicle interior and monitor for cycling points. If the LPCO does not operate, the pressures/temps will drop to the point that the evap will begin to freeze. If this occurs simply replace the LPCO and retest.
Good Luck!!!

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

Minx on Thu March 12, 2009 3:26 PM User is offlineView users profile

I appreciate y'all's interest in the system pressures and how it was converted. I've been through all that (here and here; the conversion was done by someone else), and the answer always comes down to "airflow."

This model of Explorer is known for having poor airflow. There was a service bulletin advising the addition of a heater-control valve (made no difference on my Explorer) and upgrading the fan (been there, done that). I'm at wit's end or I wouldn't even be thinking of the difficulties of adding a mister.

The truck just doesn't cool well at idle. The high side goes up, the vents go as high as 60F, and the compressor stops cycling. Everything improves when I raise RPM, start moving forward, or spray water on the grille. Since I can't/won't do the first two every time I stop at a light, I'm looking to remedy the problem with some ingenuity.

NickD on Thu March 12, 2009 5:25 PM User is offline

So you are saying you didn't do the conversion, have no idea what's in there, but want to solve it with by airflow that you already did with poor results? So now you want to spray cold water on it?

Spray cold water on it. But if the retro was done properly, would even be much cooler when you are spraying cold water on it.

Minx on Fri March 13, 2009 10:53 AM User is offlineView users profile

I found one switch here (PDF - p. G-6). I'd hoped to find it at our sponsor's site, but no luck searching.

Minx on Fri March 13, 2009 3:53 PM User is offlineView users profile

So far I've located this fascinating bit of hardware: An aerodynamic-pressure switch that senses when the car slows down, then kicks on some accessory (fan, mister, etc.) of your choice.

I might just go with an auxliary electric fan wired to this little device.

bohica2xo on Fri March 13, 2009 9:38 PM User is offline

Now, an additional fan sounds like a better idea than the "mister".

That "airflow" switch looks like a bag o' snakes in the underhood environment. Obviously not commercial automotive equipment.

I generally install a temperature switch on the condensor inlet for fan switching. I prefer to use the TO220 package switches from Cantherm, they are rated @ 1 amp for switching things like relays. A relay is a must for an electric fan. You can buy them from DigiKey for less than 9 bucks. A part number 317-1338-ND should do the trick. With a 65c rating, that translates to about 260 psi on the P/T chart.

What sort of climate do you live in?

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

iceman2555 on Sat March 14, 2009 10:50 AM User is offlineView users profile

Seems as if the are too many variables in this repair. From the statement,"it was done by someone else' .
If I missed something in one of the post......it is simply too much freon passing thru the channels of the mind.
A suggestion would be to go back and start from the beginning. Insure that the system is not over charged with lubricant. Flush it, clean it...air purge to remove all traces of residual flush chemicals.
Change the required parts,used the correct orifice tube for this vehicle, the correct type and specification of lubricant, recharge to balance temperatures within the system and retest.
As previously stated the system must be completely recharged prior to making determination of operational pressures. Pressures should not be used to determine the correct recharge rate.
Since the cooling system has been upgraded, it is quite possible that the recharge rate of 134 will be equal to the OE spec for 12.
Trying to 'fix' a system by 'trying this...trying that' is not a sound procedure.
Make the 'repair' as it should be accomplished, remove as many variables as possible and then determine performance levels.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

Minx on Mon March 16, 2009 2:46 PM User is offlineView users profile

Quote
What sort of climate do you live in?

Dallas, which is hot as Houston or Florida but not as humid. Still pretty humid, though.

Yeah, the air-pressure sensor is pretty "out there." I just thought it was a neat device and wanted the group to see it.

Thanks for the link to the supplier. So the Cantherm item -- do you fasten it to the condenser inlet pipe? Then wire it to a relay to drive the auxiliary fan?

iceman2555 on Mon March 16, 2009 5:58 PM User is offlineView users profile

Obtaining information from the original post where pressures were stated and many at that time addressed the issue with pressure readings/recharge a response was never make. It seems that the poster simply desires to address and issue that could be address by insuring that the retro was done properly. The posted pressures are a bit out of line for a retro in the temp range stated.
"Way back when" we were doing many retro's in the Dallas area....there can be tremendous amounts of heat/humidity there.....and the pressures seem to be out of line. Seems as if an attempt to recharge a retro using an assumed r12 pressure reading was used on this vehicle.
Still stand by the idea that the condition of the 'retro' needs to be addressed........paying attention to the recharge amount is of foremost importance.
Never in all the 'retros' we did was it ever necessary to install a 'mister' for the condenser. Additional fans yes....but a water mister !!!!


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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

bohica2xo on Mon March 16, 2009 6:25 PM User is offline

Iceman:

Retrofitting exploders is rarely as good as R12. They were not known for great A/C - heck even my OEM 134a system was crap. Personally I would never have retrofitted this vehicle. What is done is done however. It never really hurts to add condensor airflow anyway, especially in TX...

Minx:

If it cools well at speed, then airflow will help. Put in as much electric fan as you can fit. Your description of fitting the cantherm part is accurate. Gently clamp or wire tie the thermoswitch to the condensor inlet or suitable spot on the metal line. Use the switch to drive a relay, and the relay to run the fan(s). Keep the OEM clutch fan.

Pay attention to the setpoint of your cycling switch. You can get better overall cooling if the system spends very little time above 35f for de-icing. The cut-in pressure is more important than the cut out temperature under high heat loads - you don't want the vent temp going to 60f before the compressor re-starts.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Minx on Tue March 17, 2009 10:51 AM User is offlineView users profile

Thanks, bohica. There's a spot to one side of the trans cooler that will accommodate a 12" fan. I'll work on finding one.

Meantime, I'll see what the low-side cycling on-off pressures are. I was watching them while recharging last Saturday but didn't take notes.

Thanks also for acknowledging the Explorer of this vintage has some inherent airflow deficiencies.

If I had time, I'd take the system apart and start over. With family, house, and work, I can only devote so much time to this.

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