Oh Yes...Another A/C Question

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Aug 27, 2008 | 05:02 PM

brian42

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Lead Driver

Joined: Dec 2006

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From: San Diego, CA

Oh Yes...Another A/C Question

So, like many other SuperDuty people out there my A/C is woefully insufficient. In 'MAX' it gets pretty cool (cold if it's below 75F outside) but that's about it. I've read of putting in a valve to prevent hot water circulation. I've read that my 2003 has a valve in there already (although it may not close all the way). There's got to be more to it than that.

Is it worth evacuating the refrigerant, cleaning it out and putting a fresh charge in the system?

I don't think I need to shim the compressor because it seems to be running fine.

Is there anything I can do to increase the performance of the system short of killing flow through the heater core? I almost always have the compressor running from spring to fall to keep the cab dehydrated. It was an old ranch truck and for some reason the windows fog up at the slightest sign of moisture.

Thanks for any help.

Aug 27, 2008 | 06:00 PM

whjco

Elder User

Joined: Feb 2007

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The AC in my 2000 Excursion works pretty good. Do you know if your AC system has ever been opened up? If so, was it pumped down before the refrigerant was installed? If not, air is not compressible in the system and that will really hurt the efficiency. Also, an inadequate charge can also keep it from cooling well. While a set of refrigeration gauges are a big help in setting your charge, I've found that the charge is usually about right when condensate begins to show on the exterior of your accumulator under the hood where your low pressure hose connects.

I'm also curious about your comment about the windows fogging up easily. It sounds like moisture is getting into your truck by either leaking rain water into the cab or it also might be possible that the condensate drain on your AC evaporator is stopped up.

Aug 27, 2008 | 06:33 PM

Phrosut

Senior User

Joined: Jul 2008

Posts: 107

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From: Paradise, CA

I read that some 2003 SDs have the valve to stop flow to the heater core but I've inspected mine and it definitely doesn't. You should be able to trace both heater hoses from the firewall forward and you'll see if there's the valve in question.

I plan on installing one but it's farther down the 'to-do' list and I doubt I'll get to it before early next summer.

Phil

'03 F250 7.3L SC 2WD

Aug 27, 2008 | 06:46 PM

aldridgec

Logistics Pro

Joined: Mar 2002

Posts: 3,881

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From: Wake Forest, NC

Some adjusting of the charge could be in order, but there are lot of things to check. First is putting a set of guages on it to check the operating pressures.

Second you can make a big improvement by cutting off the heater core flow. I did this to mine, so it turns it off in the max position and it works really well. Another member here did a fancier setup so it cuts off the heater core when it is in the full cold position.

Third, if the guages show some inefficiency you can look into that as well. Condenser blockage, poor air flow through the condenser, weak fan clutch. You could have a weak compressor.

Slight correction, air doesn't carry heat well in a refrigeration system. It is compressible, but is very inefficient. Since air contains moisture, it also can damage the a/c system.

Aug 27, 2008 | 06:52 PM

mwsF250

Postmaster

Joined: Jun 2008

Posts: 2,564

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From: Wayyy NoCal, USA

I think a check up from a knowledgable A/C person is in order. I can get my cab down to comfortable even on 110 degree days.... It may take a while (10-15 minutes if I had parked in the sun and the body and upholstery are smoking hot), but it gets there.

A quick check you can do yourself: With A/C on max, shove a small thermometer in a vent. It should read well below 60 degrees within a few minutes. I'm thinking maybe even under 50. Chris can probably give a more exact figure.... Anyway, the air should be cold. If not, defininitely needs attention. Either the heater core flapper door is stuck or system has lost refrigerant.

Aug 27, 2008 | 10:39 PM

89stinger

Mountain Pass

Joined: Dec 2007

Posts: 133

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From: Queen Creek, AZ

My 03 crew cab gets cold here in AZ when its 110 outside. I do have a thermometer in the vent at the right side of the steering wheel and it consistantly blows 48 degree air.

Aug 27, 2008 | 10:59 PM

aldridgec

Logistics Pro

Joined: Mar 2002

Posts: 3,881

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From: Wake Forest, NC

AZ = NO Humidity

This year in MD has been really mild especially humidity wise and my truck seemed to get TOO cold a lot more than last year. I'm guessing SD has similar climate to Baltimore.

A 30 degree drop from ambient is an accepted rule of thumb. However, I have my own criteria. A/C was one of the first automotive systems I studied, so I tend to be particular. 45 deg vent temperature within 10 minutes of DRIVING is good. Anything lower than that and you have an exceptional system. Back in the days of r-12 and real compressors you could expect 35 degree vent temps or even lower. Some of the cars now are getting closer to that, most cars in the mid 90's when 134a was "new" were lucky to see 50.

Unfortunately, there are some cars that just won't do what they should. Others work exceptionally well. Mine does what it should, my old 97 PSD was exceptional, it was instantly cold.