2001 A/C diagnosis - what does it mean?

[chasealley]

Hi all,

My 2001 Air Conditioning isn't as cold this year as it was last year. I thought it may need some refrigerant but wanted to ask for opinions here first.

I ran through the Ford retail AC test procudure and the result (according to their charts and pinpoint tests) tells me something is wrong with the cooling system. I'm not buying that yet. Here's what I found.

Test at 1500 RPM (1474-1650 actual)
Outside Air Temp: 27C (80F)
Low side: 31-32PSI
High: 242-256PSI
Air vent: 9C (48F)
Compressor didn't seem to cycle at all. Stayed on permanently.

I should note that after the tests were done and data was recorded I noticed that my low guage didn't reset to zero - and it is a brand new guage. So the low side test is probably 5 to 8 pounds off meaning it could be anywhere from 23 - 32 PSI.

Anyway, should I fill? Ford says the vent should be in the range of 2 - 7 C, the high side between 130 and 235 or so, and the low side between 25 and 45.

I saw 12Ounce (I think) mention to fill until you are on the high side of safe. Should I top this up until I get to 45 PSI on the low side?

[12Ounce]

If you ever have reason to fill ... then fill to the "high" side of the acceptable range.

BUT, from what you're describing ... you don't (now) need more refrigerant. Your key statement was : ..."Compressor didn't seem to cycle at all. Stayed on permanently". The compressor is doing all it can. (If you added some refrigerant, it would actually do a bit less .... but that's another involved discussion.)

You have other issues. Are all the fans running? ... at highest speed? Are both the condensing and evaporating coils in good shape ... fins not bent ... fins clean? Are all the fans clean? The inside fans are notorious for getting loaded with dust ... comes from our clothes, etc.

The condensor coil is supposed to be "flow-coupled" to the radiator ... so no air can leak around the "connection" between them ... passing thru the radiator but not the condensor. So, are all these pieces in place? Plastic parts at the top and bottom of the radiator/condensor coupling? Are they joined on the sides? You may have lost some of these pieces ... they are all important.

[chasealley]

I posted a long answer but AF kicked me off. I'll try to recount as much as possible.

Fans are running. Front is clean at least. Haven't looked at rear yet. Condenser was cleaned with compressed air after removing shroud. Minor bent fins at the bottom lower grille but no different from last year.

Most important thing I can tell you is that the evaporator doesn't seem to put out much water anymore. Last year we had a lake under both front and back. This year, nothing most days. Except after a 1.5 hours highway trip. Discharge air being 11-13C at idle and 9C at 1500RPM on MAX A/C though - may not be cold enough.

After inspecting the drain holes were cleared we blew compressed air in and got a nice stream running. Which makes me think it is sitting and not draining - again maybe the high temp. After turning off the A/C the humidity gets real high in the van.

I could see that maybe the evap is the problem, but the remedy for getting water flowing in the front certainly didn't work for the back and it was equal discharge temperature. Probably indicates something else again.

The rad parts seem to be ok from what I can see. I shook both pieces around in the isolators and they looked good. Not sure about the airflow around the sides - will need to look at that today.

Are you sure you wouldn't refill with the low side pressure between 25 and 31 or so?

[12Ounce]

You will actually get better cooling if the refrigerant is a bit low. If the compressor never falls out due to inlet side low pressure then you are OK ... of course there's nothing "wrong" with toppiing it up ... just don't expect that to iimprove performance. It will keep you further away from leak issues, of course.

BTW, are you sure the compressor is never falling out?

If you have had water dam up inside the drain path, there's a good change you've got some "growth" issues on the evap coil. Have you had a chance to inspect and clean it?

There's a belly cover that's removable. Best to disconnect the hoses from the heater coil and drop it with the cover. Beware of, at least one, screw against the firewall ... I think I remember seven screws total .... but its been a few years.

[chasealley]

I didn't really observe the clutch that closely so I should double check that today. I was sitting in the van running the laptop based scantool and watching the High side pressure along with a graph of the "AC clutch command" with a refresh of 1 msec. It stayed in "1" all the time. I should verify that with the eye/ear though.

I wondered how to inspect the evap without taking the whole dash apart. Thanks for the info there on the belly cover. I'm going to take a look at that today. The van is getting a flat fixed at the moment so I'll get it back in my garage later in the day.

Also, should I perform the same evap inspection on the rear seeing as how it is performing similarly? And should I get a can of disinfectant?

[wiswind]

I have turned the A/C on so that it pulls air in from outside.....and sprayed Lysol (or other similar product) into the air intake (cabin air intake...NOT engine intake!!!!!).
This will get the mist over everything inside there.....
Do this with no one inside the car.

Also....my A/C is working just fine....and pretty much all of the fins below the bumper are seriously bent ('96 with 186K miles on it). The rest of the fins are great.

The fans running is great.....keeps the A/C working great when you are not moving....and it also keeps the engine at a more consistant temperature (none of that cycling hot / cold) as well as keeping the transmission cooler.....especially if you have an auxillary transmission cooler....then it keeps the transmission MUCH cooler.

[12Ounce]

Observe the clutch "gap" while the front and rear fans are on "hi" ... and all doors and rear hatch are open. The clutch should stay engaged during this test ... unless the suction pressure gets too low ... then you know to add refrigerant.

If you drop the belly pan, you will have good access to the fan side of the front evap coil. The rear coil is more easily accessable.

I've never had to clean the coils. I would go to a supply shop that serves the auto-ac service world ( if you have such in your area) to see what they could supply for a chemical coil cleaner. If you could spray cleaner directly on the coil and have the refuse go down the regular drain route ... it (would seem to me) to be the most effective, neatest way.

As Wiswind says, the radiator fans must run at high speed for the ac to be most effective. On the '99+, the power relays for the fan motors are between the air filter and the shock tower. They are unique in size. There are also additional smaller control relays in the fuse box underhood.

[chasealley]

Hi guys,

Here's an update on what happened today.

Got van back after being in the shop to repair a nail in the tire. Before I started working I decided to check the rear aux discharge temperature with the digital gauge. It was 22C. I knew something was funky. Ambient temp outside was about 28C. Because I couldn't get my hands on the radio removal tool I decided to go ahead and take a look at the rear system to see what was wrong and leave the front for another day.

Once trim panels were removed I began tearing down to inspect the rear evap. It was fine. Absolutely. I blew compressed air at it from every access hole I could find and all I got was a little water. Did the heater core too. Cleaned the blower motor but it was pretty clean. Observed the pipes on the evap while running. One got cool (not cold or wet) and the other got warm (could still touch it). In contrast, the pipes going to and from the front evap were both cold.

One thing I noticed that may account for some of the problems in the rear was when the rear was controlled from the front controls both the floor and overhead vents were open! When the front was set to 'rear' control and the rear controls were cold the floor vents were closed. From the front if I switched the rear fan to high it would partially open the floor again. Seems odd. All tests are done with Max AC and both fans on high. I may have to rerun these tests back and forth several times to make sure that there isn't a sticking condition or similar.

My rad cooling fans both come on when MAX is selected but I can't verify if they are in low, medium or high speed. I'm not sure how to go about that test yet.

Anyway, do the temperatures of the pipes seem right? And, does the operation of the rear controls and front controls seem wrong?

And guess what? Picked up another nail! Looks like I'm starting off tomorrow same as today.

[wiswind]

WOW! sorry about the nails.....might want to check your driveway, or someplace you regularly drive / park.

On my '96 (yours may be different) the radiator fans come on at LOW speed when the A/C is on and the vehicle is not moving a certain speed....and they will STAY on regardless of the compressor being on or not.
This should happen in ANY setting that has the A/C ON.

They cycle to High speed under certain conditions for the A/C.
If your fans are cycling.....on and off......then it is likely that your low speed fan operation is not working......as was the case with my vehicle for quite some time...until I found the issue.

There is a "LOW speed fan DROPPING RESISTOR" that is mounted on top of the metal inner bumper......behind the passenger side headlight.
Mine was broken.
I have pictures posted that show this part....and the replacement.

Now, whenever I have ANY setting that engages the A/C (including defrost), and my vehicle is not moving above a certain speed, my radiator fans are ON...and stay ON.
Real easy to check....because this will be true at idle in the driveway.

This is critical in cooling the condensor coils on the front of the radiator......it also keeps the engine at a more constant temperature when you are stuck in traffic.......and keeps the transmission cooler.

[12Ounce]

That's a real funky design of air flow control on that rear unit. It's supposed to work the same weird way from front or back so I don't understand the descrepancy in your unit. Mr Ford decided that if warm air is selected for the rear passengers they will get air flow at floor level, ... if cold air is selected it will come from the overhead vents. Mid temp selections will get you mid up/down air flow. Donknowhyitslikethis ... but you can be sure Mr Ford has your interest at heart. This all began in '99. Before then, it was even weirder!

If you want, you can disconnect the electric connector to the "mode" door motor and all air will come from overhead ... no matter the temperature. That's what I did.

Your observations about the temp of the ac tubes sent me to the shop manual..... hoping to see a sketch that would explain the piping layout of the whole system. No such luck, but with additional reading ... I think I've doped it out.

The front evap is fed refrigerant from the condensor thru a tube that has an mid-way in-line orifice ... so it would make sense that both tubes are cold right at the evap coil.

The rear evap is fed refrigerant with a tube run that has no such orifice. Expansion is managed, instead, by an "expansion valve" that is mounted right at the evap inlet .... so it would make sense that one tube is hot, one cold.

[busboy4]

Hi
Just wanted to weigh in regarding clutch cycling: My '96 manual has a chart to consult along with your "pinpoint test" observations. It indicates that at about 80F that clutch cycling is non-existent, ie on continually. As you probably know, the low side cut-out of the clutch should occur around 23PSI if memory serves. At the higher outside temps, the suction side never gets that low and the clutch stays engaged.

From the charts in my manual (again '96) your freon readings appear a bit high on both accounts with the high side being farther out of range of the charts. At 80F I show around 180-225 on the high. Anyway, for both being a bit high the solution chart focuses mostly on condenser airflow and/or cooling system (radiator) as being the problem. I know you checked the condenser visually. Is the engine operating at normal temp? The other thing as you have mentioned is fan speed and whether it ever goes to high. I can't tell you exactly how to test or know that.

Hope that maybe helps a little.

[garync1]

Yes on my 2001 I also notice air is not as cold as last year. It still with in limits but on a real hot day down south it takes a while for it to cool down. Have to roll down window that only works on drivers side both front and back passenger windows no longer work. I can fix those later. I have a feeling AC comp. May be going within the next year or so. Freon checks out fine. All vents work fine and blend doors ok as well. Fans are running to rad. With 101,000 miles it about time I guess. Getting ready to replace trans once it goes. Right now I drive it 8 miles to work and 8 miles back 8 hours later so as long as the trans does not get to operation temp or above no leaks will happen anything over that it leaks like crazy from the motor trans area. Maybe main seal or pump seal but until it goes I will keep it the way it is. Motor is in tip top shape so I think I will just replace trans when the time comes.Thought about getting rid of it. But i know it too well and for half the cost I just rather replace the trans.and drive it tell it dies. Axles shocks and struts.steering and paint and body all great..

[chasealley]

Hi all,

Thanks for the replies. I'll try to answer everything asked and give an account of what has happened so far.

First, the scantool was reporting 201F at the time of the tests. I'll have to watch that a little bit closer. As far as testing the fans, I'll try to maybe remove the relays and test them electrically first. I'll check scantool for any actuators that may enable turning it to high.

In the morning when I pull out of the garage, I turn the AC on low (been 100F here lately). After a few seconds of warming up in park the fans turn on.
After putting in drive and pulling away slowly the fans turn off. Remember the engine isn't to operating temp yet. If in MAX AC or any other time during the day like mid-morning with a warmed up engine, then the fan stays on. So I'd say that the low speed fan is probably working normal, but I'm unable to verify high speed fan. That's the one I should probably look at right away.

As for the cooling system, I did a real good flush last fall. It wasn't really dirty either, but I flushed front and back heater cores, the rad and engine, chaged the thermostat and filled with Ford coolant and distilled water. The mixture of coolant is probably a bit high because I couldn't get some of the flushing water out of the rear aux system, but I don't know if that would matter.

I did take the front apart the other day to get a look. The belly pan I couldn't get off but I removed enough to get a compressed air nozzle in there and blow. Removing the blower motor gave direct access to the evaporator and I blew that thing like crazy. Then I blew the other side through the drain. I crammed my camera in the hole and took some pictures and it looked clear. Reassembled everything with no difference. Only down to 9C on my ride home, which was still pretty nice. The next day it was down to 5! But this was morning, parked in garage overnight, so the interior hadn't been baking in the sun either. I'm sure that makes a difference.

However, I'm at 77% humidity today and I am only getting a couple drops of water out of the drain where I used to get a lake.

Wondering if that is just because it isn't getting cold enough, but also wondering if it isn't plugged or something.

Based on the fact finding, it doesn't seem like much has changed last year except for the discharge temperature. I'm still wondering if I should top that freon up just because I have a 12 ounce can sitting here.

Any thoughts where I should go next? (besides checking the fan)?

[12Ounce]

From your original pressure readings, it looks as though you're getting plenty of "pressure drop" ... that pretty much says the compressor and the evaporation devices (expansion valve on the rear, orifice on the front ...) are OK.

You've checked the coils and found them OK. Did you ever make absolutely sure the comp clutch is never falling out due too low pressure?

If so, THAT ONLY leaves the radiator area ... I think. You might put some garden hose water spray on the radiator just to see what the ac unit can do when its able to get rid of heat. I suspect the fan hi speed is not there.

[chasealley]

I still need to check the compressor clutch. I spent the evening yesterday just investigating.

There is that anomaly I'm having in the rear aux unit that seems to blow top and bottom with an air mixture sometimes. I removed all parts involved to make sure they move freely. I do have a code for a blend door failure but I can't tell if it is front or back. Either way, both seem to be closing off the heat just fine under most circumstances. Had them all removed and tested with them off.

I removed cover on the relay box and checked out the low and high speed relays. I took the cover off the relays themselves to inspect for burning....none there. Was able to get continuity on all contacts. I didn't switch it with power though so I can't verify that it actually works under normal conditions, just that the two relays have continuity at all the right points.

Funny thing, all of the relays of that size are black EXCEPT for the high speed fan relay which was gray. I'm wondering if it had been replaced at one time. All numbers were the same except for one. Does anyone know if these two relays are supposed to be identical?

To be honest though, I haven't heard that high speed fan come on all year. It was 100F out one day when I was testing. I'm going to have to find a definitive test for that. I heard the fans kick on once in the winter when the car was off though and that kind of disturbed me. I'll also do 12Ounce's test with cold water to help cool and check discharge temp. I'm going to need to check that coolant mixture too because it might be preventing the engine from reaching that 225F or so that is needed to switch the fan on.

Thanks guys. It is raining here so I'll see what I can get done later today and report back. I'm taking pics too so hopefully I can document this when done.