By flex fan do you mean no clutch? No way I'd consider that... There's a good chance your clutch is weak though, might as well replace it with the HD one if thats an option. These engines run pretty cool at idle (traffic) so way well be enough air to keep radiator happy, but not enough to feed condenser.

Have you inspected/cleaned the condenser? If its dirty, clogged with mud and bugs - that will cause your symptoms. Try shining a brite lite down behind condenser and see if its dirty.

The orifice tube or expansion valve creates a restriction in the flow of the refrigerant just before the evaporator. This is where the refrigerant goes from a liquid to a gas - the evaporation here is what make the evaporator COLD.

By changing the size of the orifice, you change the rate of evaporation - the one I used makes the air waaaay colder! This also serves as a filter, so dirt/restriction here can hurt system performance. My system worked good and had 300k miles on the factory charge when I took it apart to pull the engine. I was shocked how much crap was in the old orifice tube!!

 

First of all I have gauges, a vacuum pump and R-134a. My X system holds close to 4 lbs of 134a. So I did not want to loose the other 2.5 lbs of freon since I have no way to capture it. As you should know to charge a system properly a vacuum pump should be used for at least 1 hour to completely evacuate the system of air and moisture. But need I digress. I just wanted to know how much had leaked out compared to 3 years ago. This validated that the leak I have is very small and virtually undetectable.

Second, the Midas shop I deal with is a very good shop. They are the only people who touch my X and ZO6 other then me. And they let me watch them.

Third, no AC system is leak proof. If they were HVAC people would be out of business. Depending on the compressor design, the system connections design and condensor and evaporator design, very small leaks are hard to detect. So over time the system will loose efficiency due to loss of R-134a. Also, by not running the AC during windshield defrosting in the Winter will allow freon to leak. Why do you think when you switch the system to defrost that the AC light comes on?

My experience with HVAC is 35 years in the Navy repariing nuclear submarine mechanical and propulsion systems. I started out enlisted and I got so good at it they made me an officer. So I have been around 2 or 3 complex HVAC systems in my day. That's my story!

DSMMH

 

I'm not sure what you are getting at,
but the reason the A/C light comes on when you select defrosters
is because the A/C IS on to remove moisture from the air to
PREVENT your windows from fogging up:
cold windshield + moist air blowing on it causes them to fog up.

How would this prevent/cause freon to leak in the winter?

 

I haven't used this product yet, but I have used a similar one from another manufacturer. Can't remember the name offhand. Must have worked I was charging his system two times per year. http://www.nucalgon.com/assets/prodlit/3-52.pdf
I put dye in his system and came up with several evaporator leaks. Then we used the leak seal product.


On a technical note - vacuum pump run time is directly linked to the level of contaminants (moisture, non-condensables) in the system. The more contaminants, the more run time. Ford should have a specification on the level of dehydration, although I take mine to 500 microns or less. Measured with a micron gauge.

 

the symptom you're describing (not so cold at idle/traffic, cooler at highway) is also a sign of a dieing compressor. The compressor get tired and cannot pull a suction at slow speed. This will eventually stop pulling suction at highway speed too. A quick check of this is to check pressure on the low side of the system (where you'd hook up the recharge hose to - cheap check is a gauge from the auto parts store about $10). If at idle the reading is high (say up around 80 psi), it's most likely the compressor.

 

Does your a/c pump engage and disengage alot when at idle? Mine just started doing this and I'm going to dive into it this week sometime. Max a/c temp set to lowest(60 deg), pump kicks on for ~3 seconds then back off for ~5 seconds and keeps repeating.

 

Hi Dan,

My '97 F-150 had a similar issue, though when it cut on and off it was much more rapid. It turned out that the system was fine, but the low-pressure sensor was marginal.

It wound up eating up the clutch before we finally got it diagnosed.

 

This is often a sign of low freon. Likely you can get a DIY R134a filler-thingy and fix this yourself. Read the directions on the can and you should notice the compressor staying 'on' for longer and longer. You will have the most success doing this on a cold engine when its cool out. Dunno about your truck, but on my 7.3's the compressor will stay on until you can hang meat in the cab!

 

Well I tore into the rear climate control this weekend to see if I had a coolant leak because I saw some green fluid leaking on the tailpipe. I didn't find anything wrong with the heater, but I have lots of liquid under the rubber matting and I saw some green residue under the A/C portion, but nothing near the heater portion. I found out that A/C dye is a neon green. That's exactly what I was seeing on my tailpipe. I wasn't able to get it hooked up today to see if the refrigerant was low, but I will this week.

Is there anything I can service myself or do I have to have someone else work on it because it's the A/C?

 

Working on it yourself depends on your state regulations. If you can buy R134a in your local auto parts store, you should be OK for working on it yourself. I know of restrictions in CA and WI but check for yourself.

 

If you can determine what parts to replace, then YES - you can probably DIY. You'll still need to have the system evacuated and recharged by someone with the tools for that - but that should only cost about $100 or so (AND you can save the shop labor as well as the mark-up for the parts). Most places will tell you the accumulator/drier needs to be changed anytime ya open the system up. While this may be 'good practice' is is generally not required - especially if system still has pressure. If its been 'open' for a long time or ya had a compressor failure, then its probably necessary...

 

Bringing up an old thread of mine...

Now that I'm here in TX (YAY!) I definitely need this AC system fixed.

I took it to a shop to check it out and they said the High side of the system has too much pressure. They also said it is a sign of dessicant bag for the dryer(I think that's what it's called) is likely leaking stuff in the system.

I was quoted "Right at $1,000." by the shop to replace the compressor and dryer. I'm not sure if anything else needed to be replaced...I kind of was in shock at the price!

I've been looking at Advanced Auto at the parts and I can get them for around $200! There are a bunch of coupon codes the will bring the price much lower right now too!

If this thing is leaking the material in the system can I still do the repairs myself? Do I need to replace anything else in the system? They tech pulled out the TSB from Ford on this issue to support his claim.

As long as the truck hasn't been in the sun most of the day, it does a ok job at cooling it down. Otherwise it's blowing such hot air that it's often nicer to just roll down the windows! That's pretty sad considering we've been having several 100+ degree days.

Oh yeah, the tech mentioned something about purging the system of this material. Can I install the new parts and then let them do this or how would this need to be done?

Thanks guys!

 

I don't see why you can't change the parts yourself. You can flush the lines, evaporator, condensor, etc with denatured alcohol or the AC system flush stuff they sell at autoparts. With the lines open, blow the solvent thru each component until its clean. I've used the blow gun with suction attachment on it like this to do that:
Amazon.com: Milton S157 Siphon Spray Blow-Gun Kit w/ 8 Ft Tubing: Automotive

Use orifice tube 38369 when ya put it back together and then have the shop evacuate and recharge the system.

 

Hell, if your budget is $1000 - ya might consider one of these:
Air Conditioning Vacuum Pump - Two Stage, 3 CFM

and this:
AC Gauges - Save on this AC Manifold Gauge Set

or,,,,,,,,,,, see if the local tool rental place has a vac pump and gauges.

Btw, it was 52* here last nite and high in the mid 80's.

 

Unfortunately, the budget is not $1,000. That's why I'm looking for much cheaper alternatives. That's some good advice for the siphon attachment.