Horton E-Fan clutch

gnxtc2

Active member
Joined
Jun 22, 2011
Messages
2,207
Reaction score
4
Location
Bergen County, NJ USA
So I did the conversion using the Horton fan clutch. Wired in a manual over ride switch, coolant 210° NO temp sensor (192° T-stat) and AC high pressure switch/pigtail from a Taurus (don't have the part numbers off-hand).

The AC switch has two sets of contacts, NO/NC. The factory wiring goes to the NC contacts and fan relay control goes the NO contacts. When the AC pressure goes up, it opens and the fan kicks on.

All the sensors/switches are wired independently. Everything works as it suppose to. I am controlling the negative side of the relay coil.

What I'm experiencing with AC and its now warm enough for AC use. If I'm cruising on the highway at 70....water temp is down but the AC pressure built up which activated the fan for 5 secs.

I am thinking about installing a manual shut off switch so I can kill the fan on the highway and leave the coolant temp sensor to over ride the switch.

On a side note:
My AC compressor never seems to cycle when the AC is switched on, it always says engaged unless I turn the switch off. I sucked down the refrigerant and changed out the orifice tube (red). There was a few piece of metal on the tube (AC compressor going out). The low side was around 40 and the high side was around 300. On long trips, the evaporator would ice up and have to switch to vent to melt the ice. This issue was present prior to doing the Horton.

Billy T.
[email protected]
 

Tom S

Moderator
Joined
May 20, 2011
Messages
3,365
Reaction score
1
That is cool, I did not know anyone had figured out how to do this.

FYI my evap has iced up a few times but it took long highway driving for it to happen. I suspected my issue was from the heater core cut off or maybe a touch low on charge.
 
Joined
Jul 8, 2011
Messages
569
Reaction score
4
Location
Central CA Foothills
I think one part of this issue may be that the IC is in front of the AC condenser. Just a thought.

Also, there are robust programmable 12v timers available in industrial automotion. One could put one set to 15 or 30 seconds delay in the line, then pressure spikes wouldnt trigger the fan.

Remind mw what fan you used? I want a plastic fan and I know the 6.0 fan and Horton clutch don't work together.

Glad you are pioneering this, all of your work is very sano.
 

gnxtc2

Active member
Joined
Jun 22, 2011
Messages
2,207
Reaction score
4
Location
Bergen County, NJ USA
I used the factory OBS fan.

The Super Duty trucks have an IC in front.

The AC system in our trucks have no temp sensor telling how cold it is to turn off the compressor. The system is real basic.

I wonder how many others have the icing issue.

Billy T.
[email protected]
 
Joined
Jul 8, 2011
Messages
569
Reaction score
4
Location
Central CA Foothills
Billy,

What I meant on the IC was the order of the stack. Normally it is AC condenser, IC, Radiator.

One reason I could think of for AC head pressure to get high enough on the highway to trigger the switch would be the IC blocking ram air since it is retrofitted to the front of the stack. I'm considering mounting mine in the correct order due to the 100 plus temps around here. I think it has been done.

Also, have you checked what the setting of the high pressure switch is? There are a lot of options in the Kysor and Red Dot heavy duty AC catalogs.

I need to find a plastic fan the is dimensionally the same as the stock OBS fan.
 

Got4wd

New member
Joined
Jul 13, 2011
Messages
165
Reaction score
0
What pressure switch did you use? The big one where you have to clearance the ac hoses or the smaller one? Rusty used the small one with his Horton so maybe he will chime in on this. This is my next project, but just worries the clutch will cycle too much during the hot months......
 

gnxtc2

Active member
Joined
Jun 22, 2011
Messages
2,207
Reaction score
4
Location
Bergen County, NJ USA
Billy,

What I meant on the IC was the order of the stack. Normally it is AC condenser, IC, Radiator.

One reason I could think of for AC head pressure to get high enough on the highway to trigger the switch would be the IC blocking ram air since it is retrofitted to the front of the stack. I'm considering mounting mine in the correct order due to the 100 plus temps around here. I think it has been done.

Also, have you checked what the setting of the high pressure switch is? There are a lot of options in the Kysor and Red Dot heavy duty AC catalogs.

I need to find a plastic fan the is dimensionally the same as the stock OBS fan.

In the Horton catalog, there is mention of different fans to use but don't know if they are plastic or metal.

I don't what size of the threads are on the high pressure side is.

Once I get moving at a constant speed, the fan doesn't come on. Seems like the high pressure stabilizes. At this point, I'm wondering if I can manually turn the fan off. When it come on, it'll be on for 3-5 secs.

How much air could the fan move compared to driving at 70 MPH and ramming the air through the grill?

What pressure switch did you use? The big one where you have to clearance the ac hoses or the smaller one? Rusty used the small one with his Horton so maybe he will chime in on this. This is my next project, but just worries the clutch will cycle too much during the hot months......

I used the smaller one. Have the slightest clue what settings are.

Thinking back to the thermal clutch, you really didn't know how often it was cycling.

The low pressure switch is known as an AC cycling switch. The high pressure switch is known as a pressure switch.

Billy T.
[email protected]
 

rusty1161

Member
Joined
Jun 21, 2011
Messages
876
Reaction score
0
Location
Whittier, CA
What pressure switch did you use? The big one where you have to clearance the ac hoses or the smaller one? Rusty used the small one with his Horton so maybe he will chime in on this. This is my next project, but just worries the clutch will cycle too much during the hot months......

FWIW I used a Motorcraft YH1706 switch. Mine seems to be working fine and I definitely know when it cycles as I sit at a stoplight. I haven't driven it any distance in warm or hot weather yet, though.

Rusty
 
Joined
Jan 26, 2014
Messages
953
Reaction score
5
Location
FL
I've had this icing issue ever since I first bought my truck. I've replaced the Compressor, dryer, condenser and orifice tube with no change. In fact my ac clutch would never cycle off no matter what setting/speed it was on. I eventually started having some issues with the low pressure sensor and have it jumped with safety wire at the moment.

I'm not sure if its from a low charge or moisture in the system. The ac will get below 40* driving down the road though in Florida.
 

gnxtc2

Active member
Joined
Jun 22, 2011
Messages
2,207
Reaction score
4
Location
Bergen County, NJ USA
FWIW I used a Motorcraft YH1706 switch. Mine seems to be working fine and I definitely know when it cycles as I sit at a stoplight. I haven't driven it any distance in warm or hot weather yet, though.

Rusty
Mine cycles a stoplight also. But when it cycles, the compressor is still locked. According to the schematic, when the high pressure switch opens, the compressor clutch should drop out but something keeps the clutch locked up.
I've had this icing issue ever since I first bought my truck. I've replaced the Compressor, dryer, condenser and orifice tube with no change. In fact my ac clutch would never cycle off no matter what setting/speed it was on. I eventually started having some issues with the low pressure sensor and have it jumped with safety wire at the moment.

I'm not sure if its from a low charge or moisture in the system. The ac will get below 40* driving down the road though in Florida.
I've been battling this icing issue for years prior to intercooling my truck. I have the same issue.


Billy T.
[email protected]
 

Tom S

Moderator
Joined
May 20, 2011
Messages
3,365
Reaction score
1
Maybe this will help you, from the 97 EVTM book:

A/C clutch pressure cycling switch: Normally open at or below 24.5 PSI closed at or above 43.5 psi

A/C high pressure cut off switch: Normally open at or above 445 psi +/- 15psi normally closed at or below 260psi +/- 30psi

AC clutch field coil: Operates AC Compressor clutch when suction pressure reaches 43.5 PSI and disengages clutch when suction pressure drops below 24.5 PSI
 
Joined
Jul 8, 2011
Messages
569
Reaction score
4
Location
Central CA Foothills
Billy,

The switch pressure specs for the low side switch are set up to protect the compressor from low freon charge and normally do not come into play. If this switch is causing the compressor to cycle, the system is low on freon.

The high pressure specs quoted are for the stock high pressure switch. Remember this switch is also set up simply to protect the compressor.

Remember the switch you replaced it with has a cut out for high pressure like the original and then a seperate switch to operate the engine fan. The setting of the engine fan cut in might be too low if it operates the fan too often. This set up to use high pressure to operate the engine fan is very common with heavy trucks. There has to be various settings avalable. Red Dot and Kaysor make a lot of the switches for the HD market. This would be what they call a binary switch.
Another posibility is a time delay circuit. There arent uncommon in refuse trucks for other than AC but could still be used. What if the compressor didn't come on until 15 or 30 seconds after reaching the high pressure setting of the switch?
 

gnxtc2

Active member
Joined
Jun 22, 2011
Messages
2,207
Reaction score
4
Location
Bergen County, NJ USA
I know the low pressure side is not low, so the compressor is not cycling.

For the high pressure side, the switch is NO/NC. The NC side is connected to the truck harness as the original switch was NC. The NO side is connected to control side of the relay for the engine fan. I'm switching the negative of the relay coil. I know when the switch makes it causes the engine fan to kick on.

What I don't understand is why the compressor clutch is still engaged when the engine fan kicks on? :confused::confused::confused: Bad diode? The low and high side switches are in series.

I was driving the other day on the highway doing 70. The temp outside was 80*. The engine fan was engaged for 20 minutes. I know that I had air movement across the condenser.

I feel like installing a manual switch in series with the NO side of the high pressure side so I can shut the fan off on the highway.

Do you have any links the Kysor and Red Dot switches?

Billy T.
[email protected]
 

old man dave

New member
Joined
May 26, 2011
Messages
1,005
Reaction score
2
Location
Petaluma, CA
The A/C diode is there only to prevent/bypass a reverse polarity high voltage pulse going throught the electrical/electronic system when the clutch coil field collapses. If it wasn't there, the A/C system would still work. If it was shorted (bypassing the clutch), then the clutch would not work at all.

Are you able to check if both contacts work simutaneously? Sometimes they don't.
 

rusty1161

Member
Joined
Jun 21, 2011
Messages
876
Reaction score
0
Location
Whittier, CA
That's good info, I will check mine.

Rusty

I will say my compressor cut out while climbing the Sherwin Grade heading up to Mammoth today. Temps in the 90's, speed 60 mph, OD locked out, 2500 rpms. EGT's were 900-1000, not towing anything and water temp gauge started on "O" and headed up to the "M". Then the fan clutch engaged and the needle moved back to the "O". But, the A/C seemed the cut out, definitely not as cold as when moving over flat ground, could have been a result of all of that hot air coming off of the radiator.

Needless to say, I am a believer in the Horton fan clutch. If I had been towing, I would have been in great shape temperature wise.

Rusty
 

rusty1161

Member
Joined
Jun 21, 2011
Messages
876
Reaction score
0
Location
Whittier, CA
BTW, my truck has 3.73 gears, 33" tires and the Sherwin grade is an approximately 9 mile 6% climb from 4,000 to 8,000 feet.

Rusty
 

Tom S

Moderator
Joined
May 20, 2011
Messages
3,365
Reaction score
1
I will say my compressor cut out while climbing the Sherwin Grade heading up to Mammoth today. Temps in the 90's, speed 60 mph, OD locked out, 2500 rpms. EGT's were 900-1000, not towing anything and water temp gauge started on "O" and headed up to the "M". Then the fan clutch engaged and the needle moved back to the "O". But, the A/C seemed the cut out, definitely not as cold as when moving over flat ground, could have been a result of all of that hot air coming off of the radiator.

Needless to say, I am a believer in the Horton fan clutch. If I had been towing, I would have been in great shape temperature wise.

Rusty

Do you think the AC cutout from too high of pressure?
 

Latest posts

Members online

Top