[LoneWolf3574]

Hey all, I'm hoping someone can point me in the correct direction at the very least. Please pardon the long back story, but I'm hoping it will help in some way.

I've got 2002 Windstar that my wife drives all the time down here in the Old Pueblo (that's the Tucson area for those not in the know) and it's mostly a to & from work deal for her (about 15 miles each way). This past October, as things were cooling down into the 90's here, her ac went out and as it turned out, there was a low refrigerant level in the system. I charged it up with a can of R134a & PAG until the pressures were in the normal range for the low side. Not long after, it got cold enough outside were the ac wasn't needed until about mid-March and this issue came up again, low refrigerant. This time I charged it with a can of R134a & dye only to have the ac die a few days later due to a leak I found near the muffler in the refrigerant hose and a failed low pressure charging valve. These, as well as the accumulator/desiccant have been replaced along with 24oz of JUST R134a (front and rear ac) and 2oz of PAG46 in the accumulator, all this past weekend.

My problem is the pressures are high (~40 low & ~285 high, yeah maybe a little high there) but the temperature coming out the center vents with the ac on maximum and fans maxed is only ~70F. By what little I know, with as little humidity as we have here in this part of Arizona, the ac should be near or about 32F. Obviously the compressor is engaging, there's refrigerant, & the orifice isn't blocked or I wouldn't have the pressures I do. The fans are kicking on under the hood and in the cabin providing air flow over the expansion and condensing coils. I'm assuming the air distribution is working fine since cool air (not cold) is coming from the vents and it is coming out strong. From the information I've been able to find around the internet, it looks like it may be the blend door. I don't want to tear down the dash anymore than I have to, but I will do what is needed to keep the wife happier then this little bit of cooling coming from the vents.

At this point, I'm at a loss as to what is going wrong and needless to say, I'm confused & no expert on this kind of stuff . Any and all reasonable ideas and help would be greatly appreciated at this point. A little extra info - the van does have ~135k miles on it and had the condenser was replaced by the dealership about 3 years ago after it was punctured by a rock from the road, thank God I had gotten an extended service warranty. Don't ask how, it happened when my wife was driving and I didn't want to know. Other than that and what I just replaced, the ac system hardware is what came from the factory.

[grog11]

Your Windstar R-134a refrigerant capacity is 56oz. with rear air. You have only installed 24 oz.
It sounds like you still have air in the system along with refrigerant.
I hope you did pull a good vacuum on the system before charging.
There is an orifice tube for the front air, and the rear ac has an expansion valve attached to the back evaporator, either one of these could be partially plugged or sticking, causing limited flow, and causing high pressure.

[Skyhawk]

Ditto the above. Add: If an A/C system needs a charge then it has a leak. The A/C system is a sealed system. If the system is opened to fix a leak then it must be vacuumed down to at least 28 - 30 HG (inches of vacuum) for at least 30 to 45 minutes in order to get all of the moisture out of the system. Moisture in the system will mix with the A/C refrigerant chemicals and create an acid that will eat parts, and the moisture will also turn into steam and create high pressures. There is a way to clear the system with inert gas, such as nitrogen, but this requires professional equipment and is not a DIY project. I would also recommend a change of the filter/dryer, or as Ford calls it an accumulator, any time the system is opened. An addition of refrigerant oil is necessary anytime a part is replaced. The amount of oil will depend upon what part is replaced. There are charts for this information. There are also charts that will tell you what temperature you should get out of the vent depending upon the ambient air temperature, 30 to 40 degrees difference is common.

[LoneWolf3574]

I did pull a vacuum was pulled for about 35-40 minutes and, if I recall correctly, ambient temperatures that day were in the low 80's. The accumulator was replaced along with the low pressure service port valve (schrader), which was not holding, and the refrigerant hose, which was leaking at the muffler. I can say that I did NOT inspect either the orifice or expansion valves when I did this work.

grog11, do you know where I can find that information about how much refrigerant is in my ac system. I would check the sticker on the shroud, but it's gone missing. I want to be absolutely sure before I buy any more R134a.

Also, I just got done talking with my wife about this issue and asking her if she remembers anything else about it, she reminded me that about a year ago there was a ticking noise that was coming from in the dash somewhere (couldn't find it) that went away after a couple of weeks. Could this be the blend door I'm reading about and why things are not cooling down fully?

[grog11]

Here is an attached refrigerant capacity for Ford vehicles from Motorcraft.

So you did pull a vacuum, and that solves the air in system question, which is most likely none.
Being that you did not have a catostrophic compressor failure, you probably have no plugged orifice issue.
I would add 30 more oz. of refrigerant and while adding it, the system on max cooling, with the rear ac engaged and blowing also, feel the line under the hood to see if it is getting cold. It should. This will also tell you if the evaporator is getting cold, if it is then go back and reach under the back behind the left rear tire and feel those ac lines, they should be cold also. If no cold lines after adding refrigerant, then that could be orifice issue for the front lines not cooling, or a stuck closed expansion valve for the rear lines. It is possible to have ac working fine with only one part (front/back) of the system. I think you should also buy one can of refrigerant with dye mixed to have for future leaks if necessary while your adding.
I am alot more confident now that your refrigerant level is just low and barely cooling.
Try to get back with me on ambient temp, high psi, low psi readings, and lowest vent temp from front center vent after you run the vehicle a little bit after charging. 1500 to 2000 rpm throttle
My guess is they will settle out to normal, and then go from there if issues persist.

[grog11]

AC Pressure Reference & Vent Temperature Chart

[LoneWolf3574]

I'm sorry about being a bit of a pest on this grog , but the compressor isn't cycling on & off, wouldn't that also be an indicator of low refrigerant? That's what I first alerted to when the ac failed initially.

I'll pickup some more cans of R134a & SLOWLY add them, and I'll be sure to check those lines in the next couple of days here and keep you posted. God knows I'm a shadetree and want to get as much of this done by myself as possible before I have to break down and take it to a shop.

Knowing my luck lately, I probably do have a plugged orifice AND a failed expansion valve

[grog11]

Originally Posted by LoneWolf3574

I'm sorry about being a bit of a pest on this grog , but the compressor isn't cycling on & off, wouldn't that also be an indicator of low refrigerant? That's what I first alerted to when the ac failed initially. I'll pickup some more cans of R134a & SLOWLY add them, and I'll be sure to check those lines in the next couple of days here and keep you posted. God knows I'm a shadetree and want to get as much of this done by myself as possible before I have to break down and take it to a shop. Knowing my luck lately, I probably do have a plugged orifice AND a failed expansion valve

Hook up your gauges to the high\low ports.Start and engage the AC system.Check the pressure readings. Take a water spray hose and spray the condenser with the ac engaged. What are the readings while spraying down the condenser? As I said earlier you need a certain quantity of R134a designed by professional engineers to make your AC system function properly. That is on a motorcraft chart (56oz.). You can not just try to sneak up on it and think that you have put in enough R134a by just pressure readings. The correct way is weigh\measure the refrigerant amounts and then install it in one shot. You then have a known approved quantity in your system for it to function. No other way is acceptable for a proper functioning system.

If you don't like the psi readings after,check electrical relays, wiring,for proper function, if no trouble then, reclaim the R134a , open the lines back up and start checking for plugged condenser, orifice, drier connection plugs, hose blockages,hard piped lines etc. blow nitrogen or shop air thru to confirm. Nitrogen is the preferred gas, but a good vacuum will stave off moisture from shop air before install. sometimes these repairs are not just a simple refrigerant fill.

By any chance did you add some sort of stop leak to the system to repair your original leak? That stuff can plug things up nicely where you don't need it to.

Compressor cycling on\off can be a symptom of low pressure and charge loss, and also other problems like bad pressure switch, computer malfunction, poor wiring connections,restricted line or hose, etc.
Running a compressor with a low refrigerant charge can cause oil starvation damage to the compressor, due to inadequate refrigerant quantity that is needed to carry the oil thru the system, back to the compressor, causing early compressor failure.

[LoneWolf3574]

I see what you're saying about not "sneaking up" on the pressure with the R134a and understand. I'm pretty sure I didn't add any leak stop given the horror stories I've heard from other mechanics, but I did just grab a can for the first time back in October and I don't remember if it did or did not have any in it.

When I popped the hood to check the refrigeration lines this morning I heard the compressor cycling on and off, so I figured it was low on r134a since I added only 24oz the other day. I have added another 2.5 - 3 cans (30oz give or take) and according to the DIY filler hose with gage I've got it showed ~26psi. I'll have to wait until this weekend to get a more accurate manifold with gages from my dad or his buddy to tell you the actual pressures and temperatures. Ambient is about 60F locally at 7am this morning and the air coming out of the vents was cold enough to cause goose pimples. Condensation was also forming on the cold lines under the hood. All this with just letting the engine idle during and after adding the refrigerant.

I have to ask, especially since it's been a while since I've paid attention, is it normal to hear hissing for a couple of minutes after shutting down the engine? I'm assuming it is due to pressure equalization with in the system.

Again, I'll get those pressures and temperatures this weekend just to be sure the issue is resolved.

[grog11]

The systems can have a normal equalization sound after shutting down. Thats the R134a bubbling off internally, and stops after a few seconds. So now a full charge gets you cold air, which is good. Check the pressures with the chart and make sure they are in the guidelines. You should be ok. Settings will change with temperatures as you know, but will stay within the chart lines. Good Luck.

Don't forget to wipe clean all your work connections,and around the fill port caps, wait a few days and check over your installed connections for any oil residue, a sign of a leak.Some may just need a little tightening.

[Skyhawk]

Added notes: In this particular case I think that the compressor cycling is due to a low refrigerant charge, as stated above. Cycling can also be caused by a compressor clutch gap that is too large due to wear, or improper adjustment, as well as the possibilities mentioined above. Also note that the low pressure switch, and the high pressure switch, are intended to prevent the system (compressor) from operating in either condition. There is generally a high pressure (blow-out) valve mounted on the compressor. Refrigerant is compressed (high ppressure) into a liquid and is at -250 (aprox) F. Handle this stuff with care and protect your skin and especially your eyes.

[grog11]

Skyhawk, Your so right about safety and refrigerant handling. I would hope that anyone who is attempting to buy and load refrigerant cans with the store bought low side hose charger kit, please be aware and do some research on the proper handling and basic installation practices, before trying to do the job .

IF NEW TO REFRIGERANTS, PLEASE ASK QUESTIONS 1ST AND GET ADVICE ON REFRIGERANT WORK!

Nobody will think less of you and it just may save you from an accident.

[LoneWolf3574]

Ok we checked the pressures and temperature this morning. It was a wonderful 72F with cold air pouring out of the center console vents at a chilly 40F in about 10 minutes at idle. The low pressure was 32psi and the high was 140psi. All temperatures and pressures were measured with the vehicle at idle. Now I've just got to clean the engine compartment and check for leaks where I worked in a couple of weeks and all should be good to go.

[windstar02]

Hey LoneWolf, here are a couple of questions for you since you have an 02 and live in Arizona. I'm in Canada on the west coast where we don't use the AC very often. We were in Phoenix last August during the heat wave and really gave the AC a workout. I noticed that I would get more water under my van than what I saw under other cars in parking lots. The puddles looked to be clean water and were definetly not coolant/antifreeze.
How much water from condensation do you normally see under your windstar after the AC has been working for a while when it gets realy hot?
On one occassion I heard a hissing sound after I parked and shut off the engine. I popped the hood and could see a high pressure spray of what looked like water coming from the area where the AC tubes go into the passenger compartment. This happened during that stretch in August when ambient temperatures were getting above 110F and I think it may have been a bit more humid than normal.
I am hoping that this was just condensation and that I don't have a leak in one of the tubes or the evaporator.
The AC seemed to work OK on the drive back home.