Hi- I'm hoping someone here can help me figure this out. I have an '02 F250 7.3l and the A\C works, but not well- that can get to be a bit of an issue here in Phoenix this time of year . I just bought it this spring and it has been this way since I got it.

I checked the refrigerant pressure, and it was just a bit low so I topped it off but it made no difference. What's interesting is the compressor shows a tremendous amount of condensation-I mean WAY more than I've seen on any of my other vehicles- and the compressor itself is very, very cold.

Any ideas how I should go about solving this?
Thanks!

 

The ventilation system on these trucks is one of the biggest mistakes that Ford has made.
If you open the hood and look near the right side hinge you can see a lot of places where hot underhood air can get drawn into the climate control intake.
I've spent considerable time and effort trying to get a better source of air for the AC to do it's work with absolutely no success. I've gone so far as to remove the black covering and drill little holes in it, remove the tape over the hole on the right side, put some blockades on the right side between the air intake and the hinge area, on and on and on. Don't bother, it won't work.
I've installed TWO coolant shut off valves that are vacuum controlled via a solinoid and switch in the cab to manually cut off the flow of coolant to the heater core. When the switch is on I can turn the temperature control all the way to hot or cold and there is no change in temperature. So I am positive that the heater core has nothing to do with this problem.



The last time I was out on vacation to Cortez, CO. area I found that the harder the engine worked the hotter the air would be coming out of the vents. I'm thinking that the hot downpipe is heating up whatever air is being fed to the AC. On a long downhill stretch the AC gets VERY cold.
At this point, I've decided that short of putting a snorkel from the outside that goes directly to the AC inlet, that it's just going to have to be the way it is. My recommendation for you is to use Max AC. That draws air from the inside of the cab from the passenger's footwell.

After typing all that up, I had a thought. Remove the glovebox and you will be presented with the back side of the climate control. You'll see a panel that is held down with a lot of screws. Remove all those screws and the panel and you will be able to see inside the climate control unit, the blend door and the heater core. Make sure that something has not fallen into the is blocking the blend door in a partially open position and making some heat.

 

I wonder if wraping the downpipe with some high temp insuation would help? I notice the same thing with the efficiency of the A/C directly in relation to how hard the engine is working.

 

I'm sure that it would make a difference.

 

How is the air flow over the evaporator? Do you get a lot of air through your vents with the fan on? Your evaporator under the dash could be dirty and with restricted air flow won't allow proper heat transfer to the refrigerent.

 

Keep in mind that with conventional air conditioning systems (In your home as well), the most "cooling" you can expect is 21-24 degrees. If it is 100 outside, you can expect to get 76-79 degree air. When you recirculate it (Max air) you may get some minor increase in efficiency, but the real benefit is how much more moisture can be drawn out (Increasing comfort).

The up hill down hill thing is directly related to heat. You all know that with a diesel, more fuel = more heat. More fuel is required to maintain speed uphill, so the temps are going to rise. Watch that pyrometer some time.

The better you can insulate the "dryer", the colder (and more efficient) the A/C will be.

 

I'll be watching this one, as mine is acting exactly like Fear's, right down to the cold compressor and enormous amounts of condensation on the plumbing.

Pop

 

SpringerPop I didn't notice this detail before.
Is the entire compressor cold? Even the discharge hose? The discharge hose should be hot.
I would be thinking possibly a clogged condensor.

 

No, the compressor isn't cold, but the suction hose condenses moisture, almost up to the inlet side of the compressor. The aluminum tubing attached to the receiver/dryer gets frosty.

The story:

I've been working on Momma's Odyssey this AM. Seems it stopped A/C'ing at the height of the heat Saturday. Last time she was a "little warm", I made the mistake of just dumping in about a quarter can with just a charge hose with only a low-side gauge. Beeeeg-a mistake, but I didn't know it at the time since the ambient hasn't been really terrible. But, it was reeeeeally hot Saturday.

I have since bought a dedicated 134 manifold, so today I hooked it up and tried the A/C. Starts getting cold. Hmmmm, read gauges. Wholly Kow, Batman, pressure's WAAAAAAAY too high. Hmmm, is that the compressor straining that I hear?

Using an very amateur method, I remove some of the refrigerant, get the gauges to the high side of normal, and whip out the thermometers. Eventually, I'm able to get the duct temperature to 49 degrees with an ambient of 82. She'll be happy that it's cool, actually cold, and I'm happy I didn't blow up the compressor. ;-))) Thank goodness for high-pressure cut-offs!

Park hers on the street.

Run the truck into position, and hook up the manifold. Prop a stick against the loud pedal and turn on the A/C. It gets cool, but it always works fine first thing in the morning. The gauges are reading on the "lowish" side, but that receiver/dryer/filter is getting frosty. Inside, the ducts are around 68. OK, I need to add some to this one. Another sign is that the compressor is not cycling, but staying on. Start to add some, and in a bit, the compressor cycles off. Low side gauge takes off for the red zone (which I expected), but then, the compressor doesn't cycle back on. Hmmmmmm. I get another stick and "tap" the front face of the clutch, and VIOLA!, the compressor comes on, eventually cycling off again. I play with this a few times and can repeat it consistently. So, now I know what I've gotta' do, at least to make it stay cold during the whole day.

I'm inside right now waiting for the clutch to cool down a bit so I can remove a shim-or-two. After the clutch operates normally again, I'll properly re-charge it.

We'll see.........

The right tools. Ya' GOTTA have 'em!

But, I already KNEW that!

Pop

 

That "remove a shim" thing works like a charm, and is "duck soup simple".

Take out the small bolt that is in the center of the compressor clutch. You may need a large pair of channel-locks to keep everything from turning while you're twisting on the bolt. Then pull forward on the clutch plate. It comes right out on its splined shaft. Bend a small hook into the end of a paperclip wire, and look down in the splined recess of the piece you just removed, which is where the shims are likely to be. Mine had only one at about .040" thick down there. Hooked it and pulled it out. Fortunately, I had some bearing spacers to custom-fit the thickness of the shim I needed, and used about four of them to make a .020" shim. Stuck them down into the bottom of the recess and put the piece back on the splined compressor shaft. Tightened the bolt to about the same as it was before (just a guess on torque).

Air gap was now about .020". Started the engine and it now acts normally, clutching and de-clutching.

As I said in the previous post, the pressures were reading low, so I added about a pound of R134, but this still only gets the gauges into the "low-normal" range, and now the clutch doesn't "cycle", it just stays on. I verified that the clutch wasn't shimmed too tight by turning the system to "off", and it shuts off the compressor normally. This verifies that my clutch is now OK.

BUT, I would have expected just the opposite to occur after adding refrigerant. I wonder if the system was cycling as a result of the low-pressure switch getting activated by the suction. It also seems that the receiver/dryer plumbing isn't getting as cold. WTF? Like I said, my pressures are on the low side of the normal range for 134. In reality, I'd prefer for the system to not "cycle" normally, just "run", as it will save the clutch by not cycling.

I'll drive it for a couple of days and let you know how it goes.

Gee, ain't this fun?

Pop

 

Just a follow-up.

Air conditioning has continued to operate normally.

Happy camper here!

See, the supporter money continues to be the best money I spend on maintaining my 350.

Pop

 

I noticed the same thing about the temperature control switch the other day AFTER making an AC mod with a vacuum solenoid (I used the Ford Ranger valve that diverts the water back to the block when closed). It got me thinking that something isn't right! Now I know what the problem is: Ford, in there ultimate wisdom, set the AC up so that the compressor cycles due to pressure, NOT due to cab temperature OR temperature switch position. That means the temperature control switch just tempers the cold air coming in with heat off the heater core!! Once you place a solenoid valve running from the white OR the red vacuum hose - you have lost the ability to change the temperature of the air coming out of the air conditioner (in AC MAX for the white hose and in VENT, AC, and AC MAX for the red hose). I will say that my air conditioner will freeze my wide butt now and that the VENT position has nice cool air in the morning and night so I don't have to run the air conditioner as much, but being unable to adjust the temperature it is a pain in the butt! Now others may have known that the temperature switch introduced warm air off the heater core, but I thought it was a thermostat which cycled the compressor to control temperature.

If anyone can think of a way to still allow me to have cold air coming out in the VENT position AND allow me to modify the air temperature coming out in the AC position, I am all ears .

Neal

 

My method as more or less outlined in an earlier post is the only way I have found in my nearly 45 years of playing with vehicles. It works fine, but you have to get under the hood when you want a big change in temp. Now using a ball type valve you can slow the hot water way down, or vice-verse. I knew all along what it was that controlled just how hot or cold was controlled and to tell you the truth I thought everyone did. I also knew you were going to freeze your a$$ off, sooner than later.

 

I've spent some time studying the way that my truck has been constructed in regards to getting air to the air intake for the climate control.
It appears to me that there is a gap in the body of the truck below the right hood hinge that is allowing hot underhood air to make it's way from the engine compartment and into the air intake. I've come to the conclusion that the only way to get some nice cool outside air into the air intake is to somehow make a snorkel that is similar to an engine air intake on a Jeep that is made for extremly deep water crossings.
As far as your solinoid design, try my idea with the electric valve and the switch and get the vacuum source directly from the reservoir. It does it's job very well in cutting off the flow of coolant for the heater core to the point that I can set the temperature all the way to hot and have no change in temperature coming out of the vents. Turn the switch off, coolant flows, and heat starts coming out. From there I control the heat as normal.
That doesn't solve the problem of the air coming into the AC is already hot, that problem is upstream in the overall design of the truck.




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