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05 F-250 terrible AC performance Pages: 12

jed1154 on Sun May 17, 2009 6:57 PM User is offline

Year: 05
Make:
Engine Size: DIesel

I had my truck in the shop last year for a poor cooling, and they evacuated it and recharged it. It seems to work OK, when driving, about 40 degrees...as long as you are moving. When you stop, however, the temp goes up about 5-10 degrees if its on recirc, and about 20 degrees if its on outside air. The other thing is the other day, it was 85 out and somewhat humid and the truck was good and hot inside. I fired it up, put it on max ac, and bumped up the idle to about 1500 and let it run for a few mins...maybe 7-10 mins. It never got colder than 60 degrees. After driving down the road for a few mins, it eventually got back down to 40. Generally speaking i can get 40 degree vent temps while driving whether its 90 or 110 outside.


My question is, why is the 05 super duties system so piss poor? What is it about this system that makes it work so inefficiently? It has a heater core shutoff, so thats not a problem. Is there anything i can do about it except replace the truck? DOes anyone else think it should perform better than that?

Edited: Sun May 17, 2009 at 7:00 PM by jed1154

Chick on Sun May 17, 2009 7:07 PM User is offlineView users profile

without pressures at idle and moving if possible, it's just a guess, but it appears you have poor air flow over the condenser, time to change the clutch fan for one..If you can get the pressures we can tell better.. Once you have the gages on it, "mist" water on the condenser and see if the high side falls like a rock, if it does, it will confirm poor airflow over the condenser..Hope this helps...

I see that truck uses an electric clutch lock up, make sure it's plugged in and that the the fan locks up when the AC is turned on... Not sure how it operates, but might have a fuse?? someone with more knowledge should be along to add to this..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Sun May 17, 2009 at 7:31 PM by Chick

bohica2xo on Sun May 17, 2009 8:00 PM User is offline

1) Clean the heat exchanger stack.

2) Replace the fan clutch if it has 50k miles on it

Do you live in a warm, humid, rural area?

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.

jed1154 on Sun May 17, 2009 9:31 PM User is offline

Yeah, warm and humid. THe truck has 40k miles. THe condensor is clean, no bugs, and these tests were done with elevated idle. I have a switch to kick up the RPM to 1500 or so. Once the system has been running for a while, i can keep the RPM up and keep the temps cool, but its impossible if starting from a hot truck. I know its impossible to tell without gauge readings, but all i have to go on is the ford tech that said they evacuated and refilled to specs and that it was a 'little low' from the factory, which apparantly is not uncommon. At any rate, it SHOULD be filled right.

Edited: Sun May 17, 2009 at 9:34 PM by jed1154

Chick on Sun May 17, 2009 9:36 PM User is offlineView users profile

You know it can cool, evident on going down the road, that is a sign of poor airflow.. Clutch fan is not doing it's job..Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

jed1154 on Mon May 18, 2009 10:15 AM User is offline

Ill try cleaning the coils somehow. However, it may be just the way it is. If it can't draw enough air with the fan screaming at 1500 RPM, im not sure what there is to be done about it. Its a diesel, so it MAY have another cooler attached to the radiator, but im not sure, so that may contribute to it. I registered a vent temp of 33 in another vehicle of mine....is that even possible? It was 65 out this morning.

Chick on Mon May 18, 2009 10:42 AM User is offlineView users profile

sure it's possible at that ambient, but it can't go lower or it will freeze the water on the evap.. if it's an O tube system, it will cycle off before that, but back to the truck, you have to be sure the fan is locking up, some will just turn but that doesn't mean it's pulling a lot of air..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

jed1154 on Mon May 18, 2009 11:17 AM User is offline

Apparantly on my truck, its a electronically controlled. So, until the engine gets 'hot', it wont really pull that much air. However, at 90 degrees, with it 'idling' at 1500 RPM, which i can make it do, it will get warm enough to 'lock' up the fan, because it sounds like a jet when it does. It doesnt really cause it to cool that much better, like I said, at 85-90, idling on max after sitting in teh sun for a few hours, it won't get below 60 until you start moving....maybe it will, but it wont happen before 10 mins. I havent let it sit any longer than that.

bohica2xo on Mon May 18, 2009 12:00 PM User is offline

Jed:

Ok, you have the electric clutch. Not all 05's did, but we can scratch the clutch off the list. That leaves the air path.

Condensors plug up with tiny bugs & dirt, below the surface. The fins on newer condensors are pretty dense. You might be surprised how dirty a "clean" condensor can be.

You should first pull the top cover for the heat exchanger stack. Inspect the areas between the heat exchangers for debris. I can't tell you how stuff gets in there, but I have found feathers, leaves, and other larger debris in that area before.

To clean the condensor you may need to remove the grille for better access. Start with a cold, dry condensor. Use a surfactant like Simple Green or Zep Citrus, and spray it full strength deep into the fins. Let it stand foe a fw minutes, and rinse it out with a garden hose. Avoid using a high pressure washer, because you can flatten the fins in a second - and spend all day combing them back up. It may take a couple of applications before you see clear rinse water.

To inspect the air path, use a droplight in the fan shroud at night. look through the front of the condensor carefully, and be sure there are no dark spots.

Blockage in any part of the heat exchanger stack airflow can cause this issue. Those trucks have a lot of excess cooling capacity, and the engine temp will not climb with a badly blocked air path.

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.

Edited: Mon May 18, 2009 at 1:15 PM by bohica2xo

Chick on Mon May 18, 2009 4:53 PM User is offlineView users profile

bohica2xo, shouldn't the computer turn the fan on when the AC is called for also? or the high side pressure switch? It does seem to be an airflow problem, and I don't work on diesels, at least none with this problem, but I can't remember if the fan locks up when the AC is on as well as engine temp.,..???

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

bohica2xo on Mon May 18, 2009 5:02 PM User is offline

Chick:

I honestly can't recall what the 05 protocol was, I will have to look. Around here most of them are overridden with a manual switch, the SD diesels sound like a DC3 on a takeoff roll driving diwn the blvd...

Could be a sensor failure, but it should have set a code.

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.

Chick on Mon May 18, 2009 5:14 PM User is offlineView users profile

Haha, they are no quieter here Bohica... I just never heard this complaint where a guy is thinking of selling his truck.. Has to be a simple answer to a perplexing problem, maybe over riding the clutch fan with a switch is the answer??

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

jed1154 on Mon May 18, 2009 5:28 PM User is offline

I believe there is a TSB that fixes the programming on the truck so that it operates as you state. They don't do it unless you have AC problems. And im not replacing the truck, that was a figure of speech. For crying out loud, its at 40 when rolling down the road, it is what it is. The fins are clean, but i haevnt looked inside or between the radiators. Im on a dusty road, so maybe it needs a hose down. My other truck has all sorts of bugs and stuff on the radiator...no problems with its system.

bohica2xo on Mon May 18, 2009 5:30 PM User is offline

Chick:

I just looked it up. The protocol is for "optimized fan speed" based on ECT, EOT, TFT & IAT, as well as A/C operation. They PWM the fan speed, so full speed is not commanded right away.

It is possible that the ECT sensor is bad. The two fan codes would be P0480 (fan control circuit) and P0528 (fan speed sensor failure), but his fan does seem to run, sometimes.

The diesel runs a dual pressure switch (located right front of engine) that is more likely culprit. 4 wires on switch are RED/YEL, TAN/RED, BLK/YEL, VIO. If this switch does not work properly, the PCM will not know the head pressure is high.

The codes should be checked of course. Jumpering the BLK/YEL wire to the Violet wire would simulate the high head pressure command signal for testing - the fan should speed up.

Thanks for the nudge Chick. I should have looked closer the first time.

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.

jed1154 on Mon May 18, 2009 10:47 PM User is offline

Cycling switch...is that the same as what you are talking about? That was replaced already if it is. I looked at the radiator where the AC lines go in. There are a couple of bugs, but nothing major, in fact, id be hard pressed to warrant washing anything off. The truck lives under cover and is rarely driven at night, so its bug intake is pretty minimal. From what I understand, the super dutys just dont cool 'as well' as other vehicle...something about condensor size vs. air needed to cool the cab....i dont know. Has this been your experience? I mean, from the sounds of it, given that it cools well at highway speeds, it may just be the way it is. Is that the consensus? My F-150 i can get down to 35, easy, in fact, from the time i fire it up in the parking garage to the time i get down from the third floor to ground level, its already at 40 out of the vents in dry weather. I can get 35 out of it within 10 mins. THe super duty won't see anything lower than 40...ever. The dealer says thats the best it can do, and its been charged once, and evacuated and charged to spec the second time...where it cools as it does now, which is a huge improvement over what it WAS doing.

bohica2xo on Tue May 19, 2009 11:25 AM User is offline

Jed:

The cycling switch is a different animal on that truck. The cycling switch in on the low pressure side, the dual pressure switch is on the high side. The dual pressure switch is actually two seperate switches inside. One switch is the HPCO, and the second switch indicates head pressure requiring more fan speed.

Find the connector with the 4 wires described above on a switch mounted to the high side line and you have located it. If this switch is bad there will be no codes set.

Here in Las Vegas it is common to hear the SD's howling down the road. I know the ambulances & tow trucks run a fan override that runs the fan 100% in town. I can check to see what they are doing to make that happen.

I have never heard an SD owner complain about poor A/C performance, but again I hear a lot of fan noise. If you can, check the codes to be sure there are none of the codes I listed previously. Obviously if you can get 40 degree discharge on the highway, you need more condensor airflow in town. I will be back to this thread with more fan info when I have it.

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.

jed1154 on Tue May 19, 2009 11:43 AM User is offline

Thats cool...thanks bohica!

jed1154 on Wed May 20, 2009 10:47 AM User is offline

Can someone explain this to me....

Why is it that I can reach 40 degree vent temps when its 95-100 degrees out, but can't get lower than about 45 when its 75 outside? Both tested on identical settings. This is wierd to me.

bohica2xo on Wed May 20, 2009 1:33 PM User is offline

Jed:

The reason for the temp differential when cold is the CCOT system. The OT blows excess refrigerant into the evaporator core at low heat loads. The excess liquid stays in the accumulator, lowering the system pressure - and keeping the compressor off for longer periods. At high ambients the heat load & higher underhood temps keep the low side high enough to run the compressor pretty much continously. The 45 (or 40) degrees at the vent is actually the average of the evaporator temperatures.

If you live in a dry climate, the time the evaporator spends above freezing can be reduced. This reduces the vent temperatures. Making incremental adjustments can produce very cold vent temps here in the desert, but my evaporator ices up badly in Grand Forks. This is the reason your F150 has colder vent temps, the cycling switch is set lower.
.

Now, about the fan issues.

I stopped by the ambulance shop to see what mods they have made. They use a couple of relays, and run the fan up whenever the A/C is on. The second relay runs the fan to 100% anytime they are running Code 3 - probably not something you need.

The local tow services all seem to howl, all the time. I checked one SD tow truck at a fuel pump yesterday - they simply put a scotchlock connector on the two wires from the head pressure side of the switch, effectively leaving it on all of the time. This does not run the fan 100%, but bumps it to at least 50% drive.

My ASE mechanic pal tells me that switch does crap out often enough. Seems the circuit is only about 20 miliamps, and a little crap on a contact is all it takes for the signal to stop. He prefers the relay from the compressor clutch so it cycles with the compressor.

So, you options seem to be test/replace the switch, or bypass/short the switch. With a little work, your SD should be able run the wife right out of the cab with the A/C...

I could find no TSB relating to either the A/C or cooling fan & this issue. I will keep peeking under SD hoods this week for fun.

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.

jed1154 on Wed May 20, 2009 2:14 PM User is offline

Wait...what is the reason teh F-150 performs better? It doesn freeze up ever that Im aware of. I dont understand why its switch would operate under a different set of parameters than the super duty, in other words, why is it 'set' lower than the Super duty?

Also, what is this 'incremental adjustment' that can be made to produce cold vent temps.

I hate to sound stupid or like im not reading, but are we talking about the cycling switch or the dual pressure switch....it sounds like its a good switch thats just operating under the parameters it was designed for. I know its been replaced because the dealer did it. They said it was bad or inconsistent or something. How do I test it? What again makes you think this switch is on the fritz?

Edited: Wed May 20, 2009 at 2:23 PM by jed1154

bohica2xo on Thu May 21, 2009 2:50 AM User is offline

Jed:

The cycling switch is what controls the minimum evaporator temperature in both trucks. It is installed in the low side of the system. Because they are production parts, there is some tolerance in the setpoint - they may have actually been made by two different vendors. Any cycling switch will have some hysteresis, or delay in switching. A switch that opens @ 25 psi may not close again until 40 psi. Not all cycling switches are adjustable, but with an adjustable switch it is possible to adjust the setpoint to start cooling again at say 30 psi instead of 40. This means of course that the evaporator dips below freezing for some time, and builds some ice. As long as the time spent above freezing is long enough to shed the ice, you can do this indefinitely.

If the humidity is very low (8% here today) I can let the evaporator spend most of it's time at 25f without ice buildup. The same setting will build a solid block of ice in a few minutes in North Dakota. Vehicle manufacturers must build a unit that will work anyplace in the US without regional adjustments. So you get 40f vents. An adjustable switch can be installed in place of a fixed switch, but you may have to change the connector on the harness. I believe your '05 has a fixed cycling switch - Tim can supply the adjustable unit & pigtail if it is needed.

Your SD is also equipped with a Dual Switch. This switch is installed in the high side of the system. One part of the switch is a normally closed contact, that will open if the system pressure goes too high - about 400 psi, and will shut down the compressor until things drop below about 350 psi.

The second half of the dual switch is what feeds a signal back to the cooling fan clutch. This switch is normally open, and closes when the high side reaches about 275 psi - telling the fan to speed up. This half of the dual switch is probably where your cooling issue is, and is the part of the switch that I am finding jumpered. Jumpering this switch would make the PCM believe that the high side was already above the limit, and would increase the cooling fan speed. Apparently the dual switch does fail often enough to make me suspect that yours is not functioning properly.

Hope this makes it a bit more clear.

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.

jed1154 on Sun May 31, 2009 11:05 AM User is offline

It could be that switch is the culprit. However, i am beginning to think its just the 'logic' in the auto climate control. My other truck for a given temperature will put it at a lower speed, but colder temp...my SD will put it at a warmer temp but a higher speed. I have also noticed that if its 50 degrees outside and you put the AC in manual mode and set it as cold as it will go, you wont get anywhere close to 50 degree vent temps...maybe 60, but if its 100 out, you can squeek it down to 40 no problem. I opened the hood with it running and the AC lines are uncomfortably cold and sweating like crazy, so, i was wondering if it would help if i insulated them somehow....

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