AC lines freezing up

[pcsgrp35se]

My 10' sport is in the shop now for the 6th or 7th time. Last summer on a long tip, my AC went south. I started to lose cool air and then no volumn out of the ducts. I shut off the ac and after about 5 minutes it would work again. I saw that the lines were frozen solid so on a 6 hour trip home, I had to manually cycle the a/c switch about every 15 minutes not to boil in the 90+ temps. Took it to the dealer (I have the extended warrantee) and they said the computer needed upgrading......still didn't fix the problem. Took it back again and they took all the Freon out and that didn't work. Another time they checked the drain to see if it was clogged but it was open...........still freezing up. Went back another time to replace one of the two sensors and again, same problem. Back in again to try something else and off I went to florida. On the way to florida, when it got warm (it was November) ac froze up again after about 30 minutes on in not very humid conditions. Took it to a florida ford dealer since in the humid conditions in south florida, it froze up in 10 minutes. They had the car for a week (gave me the loaner) and they changed all the lines from the condenser to the evaporator, a vent door actuator the sensor again. They said that whoever put in the original sensor installed the incorrect one for my car! After a week, they called me to say that they still didn't have the problem fixed and were working with ford who wanted them to start going thru all the wiring harness to see if there was a short or some other problem. Unfortunately, I had to head back north so I couldn't have them do it. When I came back to NJ, the service department saw what was in the system and they messed around with all the connections to ensure good contact and said it was fixed. Here we are in the spring and you guessed it, after 20 minutes the lines freeze up. They now have the car again trying to get the ac to work. Anyone else have similar problems or suggestions on what the problem is? I would think that ford has spent thousands on trying to fix this that someone would be able to figure this one out. I was thinking that perhaps something is broken in the evaporator and that is not allowing air to go thru. I doubt it is dirt since I change the cabin filter every 6 months and they usually come out in good shape.

[Monochrome11]

Are you sure the lines are freezing up? Maybe I misunderstand what you are saying. This type of thing is usually the A/C condenser icing up and blocking the air flow through it. This is caused by the condenser getting too cold and freezing the moisture in the air that is flowing through it. This allows ice to slowly build up on the condenser fins and eventually block the air flow. Turning off the A/C is allows the ice to melt and you can get air flowing again.

 

I don't know how the modern A/C systems control this but older style A/C systems limited the pressure on the high pressure side. Once it reached a set pressure the A/C compressor clutch would disengage until the pressure dropped below a set point.

 

I had a 89 Ranger that would do the same thing as your car. It had an adjustable pressure regulator on it and I kept adjusting it until the problem went away. I know newer automobile A/C systems do not have this type of control and are more complex. I have been told there is a sensor on or near the A.C condenser that sometimes goes bad and causes this problem. Ford dealer and engineers should certainly know about this so there must be some unusual problem with you car that is hard to find.

 

It could be your A/C system Is working properly but the control to the A/C clutch has a problem. Something like a stuck relay or a short that keeps the A/C clutch from disengaging to keep the condenser from freezing. The complex systems they have today make these kind of problems difficult to diagnose.

[pcsgrp35se]

It is a combination of both. With the ac on after about 20 minutes I lose air flow and cooling from the vents. If I open the hood, both lines are frozen white sometimes with at least 1/8 ice coating on both lines going to the condenser. From what I understand, they applied one of the TSBs I believe it was the reprogramming of the computer as well as changed out sensors and the mixing door actuator sensor. They also replaced all the lines from the evaporator and condenser (seems that the connectors on the fords are not all that great and they leak. This was done in florida. The tech told me that there may have been a leak in one of the lines but it is also possible that he identified some tracer dye that might have escaped when they were trying other things at the dealer here in NJ. I don't think the lines were leaking. Clearly the evaporator is freezing up. My concern now is how often am I going to have to try and get this fixed since they told me they fixed it several times and they didn't. I don't think the lemon law comes into play since I am under the extended warrantee but I have to figure the only way to solve this problem is to replace the entire system including controllers, computers, lines, evaporator, condensers and all the other parts. It would be less expensive for ford to buy me out of the car which would be fine with me if I didn't like the car but I really like my sport and don't want a different car

[FusionDiffusion]

Both lines have frost under the hood? If you look in the front grille do you see any frost anywhere in on the condenser coil? You may have a blockage somewhere on the high side creating a pressure drop since the high line is frozen (that line should never be colder than ambient temp).

 

The two sensors are an evaporator temp sensor that is supposed to turn of the compressor when it gets to freezing and a pressure sensor on the low side.

[Monochrome11]

It is not uncommon for the A/C line to get some ice on it. That should not cause a problem with the Freon inside. It is an indicator that the A/C system is working well and maybe too well in your case.

 

I clearly got the terminology mixed up in my prior post. I kept referring to the condenser but meant to say evaporator. I am not sure it is even possible to ice up the condenser.

[FusionDiffusion]

Actually with the way the Fusion A/C system is set up you should never see frost on the lines (it will shut off the compressor before the line gets to the freezing point). The most you should see is condensation on the suction line. However frost on the liquid line (smaller line) should never be happening regardless of the A/C system type. Liquid line should always be at ambient temp or above (typically 20-30ºF above ambient). If that line ever feels cold it means you have a pressure drop that shouldn't be there. Blockages will create pressure drops, so the question is where is the blockage? They replaced the lines, but it's possible the blockage is inside the condenser coil. If it is, then you might see frost on the parts downstream of the blockage.

 

Another question I have for the OP is whether the compressor is running continuously when the A/C is freezing up or whether it is cycling?

Edited May 15, 2013 by FusionDiffusion

[thefoeyouknow]

It's the evaporator that's icing up. The PCM isn't cycling the compressor off. Why? That's the question isn't it. The way i see it, the 2 main ways the clutch disengages on fusion are: Low suction line pressure-the cycling switch signals the PCM, the PCM shuts down the compressor field until pressure climbs above 42PSI, 2nd: The Evaporator Temp Sensor shows below desired discharge temp and the PCM releases the compressor clutch to prevent evaporator icing.

When the EvapTemp sensor is open, the PCM sees that the evaptemp is -40f, and will not engage the compressor clutch, if the sensor is shorted together, the PCM sees 255f, and THAT is what I think you're getting. The PCM thinks the evaporator isn't cooling enough, so it doesn't shutdown the clutch, and before long the evaporator ices up. You've got a short in the harness someplace, and from the tech's perspective, that's a bitch. It's been a while, though, and I would say it's time to overlay both sides of the circuit from the sensor to the PCM and see what happens. I work as a Ford Dealership tech, I do Electrical and HVAC, nothing else. I'm a specialist which among Dealer Techs is becoming more and more rare. You need a specialist tech.

[FusionDiffusion]

A short keeping the compressor on all the time doesn't explain the frozen liquid line though? I agree the evaporator is freezing up and blocking airflow, but I'm thinking it's because the refrigerant coming into it is too cold due to an upstream pressure drop.

[thefoeyouknow]

With an upstream pressure drop his evap would never ice up. I think he doesn't know what's happening and is describing it as best as he can with his limited knowledge of air conditioning. Honestly, how can he look at the lines and knw they're "frozen solid" the lines can't freeze solid, and the high side line isn't really visible from above the car. Best bet he's seeing frost on the low side line, which in mid to high humidity levels, is completely normal. On the other hand, his description of a loss of airflow and multiple shops' inability to address it is most telling. He's icing up the evaporator, nothing more. I wish I knew what the ACP and evaptemp PIDs were doing.

[pcsgrp35se]

When I open the hood, both lines have a coating of ice on them and where the lines go into the firewall, the ice seems to be heavier. I am too frustrated because it really seems like the evaporator is freezing up (no air flow). I questioned the tech a number of times to see if there is a problem with the evaporator and they tell me no. As I indicated, Ford service in Naples florida changed the lines going to and from the condenser. I can't see if the condenser is freezing up but the lines that go into the condenser have ice on them. One tech cleaned all the contacts and they thought that would work but it didn't. I was with them one day when they checked to see if the drain was clogged and it was open. Several of the techs are scratching their heads on this one. Ford wanted the tech to start tracing each of the wires in the harness when I was in florida (as well as here in NJ when I came back) but they didn't do that. I assume that Ford is going to have them do this testing this week. I wonder if the computer is the problem and needs to be replaced? I am almost positive that they changed the sensor in the vent but what scares me is the tech in florida said when he had to change a sensor and I think he said that the tech in NJ installed the wrong sensor. I wonder if the sport with climate control and another option Fusion have different sensors? Could they have upgraded the program (as required by the tsb) with the incorrect update? I am finding this very frustrating. Last year everytime I put car into reverse the ringing from the sensors kept going. They reprogrammed whatever they had to do, changed a sensor in the rear bumper and after several attempts of fixing, had to change the instrument cluster which was where they found the problem.

[FusionDiffusion]

I don't think there is a problem with the evaporator either. It's just freezing up (which is caused by other problems).

 

If you look at the end of the condenser in the engine bay there are two connections. The top one is a rubber hose that transitions to a metal line that goes into the condenser, which comes from the compressor. That line should be hot. The bottom line runs from the condenser back to the firewall and has the high pressure service port. The bottom line should be less hot than the top line.

 

If both of those small lines going into the condenser are cold, then the temp sensor is either not working or your compressor is shot (or perhaps both). If one line it hot and the other one is freezing cold then you probably have a blockage.

 

Either way, the techs should be verifying the reading on the evap temp sensor to make sure it's working.

[thefoeyouknow]

One thing is for certain, that compressor isn't disengaging. I'd like to know what lines were replaced. Your service invoices should have the part numbers, or you could post your VIN number and I can pull your warranty history.

[pcsgrp35se]

Here is some of the information about the attempts this one is from florida where they replaced the lines

 

1-AE5Z-19E616-A MOTOR ASY

1-AE6Z19835-C TUBE ASY

1-AE6Z-19D734-A TUBE ASY

29-YN-19 REFRIGERANT

1-YN-12-D OIL-COMPRES

1-AE5Z-19849-A VALVE ASY-EV

 

this was the work done in November. In October before I had to go to florida, the NJ dealer did the following

 

19700A PRESSURE LEAK TEST, DISCHARGE, EVACUATE AND CHARGE AIR CONDIONING SYSTEM

1-AE5Z-19849-A VALVE ASY-EVAPORATOR EXPANSION

14-YN-19-REFRIGERANT-R-134A

19700A13 VALVE-AIR CONDITIONER EVAPORATOR EXPANSION-REPLACE (19849)

1700A13 FILL AND BLEED AC SYSTEM

19700A PRESSURIZE, LEAK TEST, CISCHARGE, EVACUATE AND CHARGE AIR CONDITIONING SYSTEM

fc: C20 42

PART #: AE5Z-19849-A

 

Some of the other paperwork is in the car at the dealer. The first attempt they said that they had to reprogram the computer that was back in late July, early August. That fix didn't work I still had the freezing up issue. Since I was recovering from my cancer surgery for about a month, I didn't drive the car for more then 10 or 15 minutes at a time so everything seemed good so I thought it was fixed. When I finally drove for more then an hour, the a/c stopped blowing air and froze up again. When I took it in they said the had to reprogram the computer but didn't give me any paperwork on it, said it was not necessary. I figured that they put in the new program. They also said that they ran it for hours and it didn't freeze up. I noticed that they had run it for hours since I left it with a full tank and it was about 1/3 full. I also noticed that they ran it with the a/c on max with recirculation. The next day when I used the a/c with the temp set at 70 an full automatic, the lines froze up again. When I took it back to show them, they pulled the car into the service area to check the evaporator drain and it was clear. Two techs manually disconnected the sensor that cycles the compressor and they also listened to see if the compressor was cycling and at that time it was cycling. I needed the use of a car and they didn't have a loaner available so I took it back the following week which was the October work. If you still need the vin let me know and I will send it to you.

[thefoeyouknow]

What I'm seeing here is a right side blend door actuator, an AC compressor manifold and what might be the line from the condenser halfway to the evaporator, and a thermostatic expansion valve, which they replaced again, service part warranty on the next visit. I'm not seeing a temp sensor. If you don't mind, why don't you send me that VIN.

[pcsgrp35se]

Sent via PM. One thing I am recalling...............they tested two sensors, I think they thought one was someplace near the firewall and the other near the compressor but that was a while ago. This problem occurred once when I first got the car. I was driving on a very humid day with the temp at 60 and the fan blower on slow and it stopped blowing air. I was near a ford dealer out in PA and while waiting for them to look at it, saw a huge pool of water under the car. When I started the car and ran the a/c it worked without any issue until last summer. I also had a problem with the outside temp indicator. It would never read the correct temp so on some of those very hot 100+ days we got two summers ago, it would read 75deg and the ac wouldn't cool all that good on auto. I think the service department needed to reprogram something and then it worked fine. The tech said that the improper reading could mess up the a/c on auto

Edited May 17, 2013 by pcsgrp35se

[FusionDiffusion]

Yeah, I'm thinking the evaporator temp sensor was not replaced since the whole dash has to come out and they were lazy. All the temp sensors need to work for the system to operate correctly.

 

System probably works fine with the blower on high because the heat load is enough to prevent the evaporator from freezing. On low fan speed there is too much cooling and it freezes. They need to test the A/C on both high and low fan speeds to evaluate it properly.

[thefoeyouknow]

I've got the warranty history, it's been replaced twice. I can't tell a whole lot more, because the tech that's been working on it writes stories like: "Verified... tested... replaced..." Not even joking, it's amazing that Ford doesn't kick back all their stuff. Techs like that cause warranty audits.

Edited May 18, 2013 by thefoeyouknow

[motorcyclist]

If your liquid line is frosted, you have a restriction, likely in the liquid filter, although if this were the case, your suction line would not be frosted due to starving the evaporator. It sounds to me as if there is no air flow across the evaporator causing liquid floodback to the compressor, also causing a much lower suction temp. you need to put a set of gauges on to correctly diagnose the problem. your suction pressure should be above freezing point,(higher than 28 psi on R134A), more so at least +40 deg or35 psi, if you have good air flow across the evap especially on a hot day you shound never see it at freezing point. While I have not done much work on automotive ac systems, I have worked in the comercial refrigeration trade over 30 years and this sounds like no air flow across evap causing the liquid refrigerant not ot boil off to a vapor, and therefore icing up the evap.

Edited May 20, 2013 by motorcyclist

[pcsgrp35se]

Fortunately, I have the ford extended warrantee so sooner or later it is going to get fixed. Still don't know if they did any work at all on it last week and nobody has given me a call with an estimate on how long it is going to take. In the mean time, I will drive one of the loner cars. Would have been nice if I got a MKS but I will make due with the focus. Boy, that thing go a long way on a gallon of gas! I am wondering how much Ford has already spent trying to get to the bottom of this. I bet it would be more cost effective to buy me out and get me into a new car that it is going to cost to find this problem if they have a electrical issue and have to hunt it down to get to a solution

[pcsgrp35se]

Here it is August and my a/c problem is still not resolved. Ford had the car for over a month awaiting a FSE who told them to again change the evaporator temp sensor which they did and the problem still exists. Although I have figured out how to live with it, I shut off the ac button when air flow starts to get warm and low for a few minutes until the evaporator thaws and then use the a/c again. I find that sitting in traffic I can go longer before freezing but driving at normal speeds, it stops working faster. The latest that they can come up with is to change out the condenser. To me that doesn't make any sense unless the dryer is part of the condenser part itself. If anything, I would think that with the hundreds of freeze thaw cycles the evaporator has gone thru, the tubing in the evaporator might have been pinched causing more freezing of the evaporator itself. I can't believe that the dealer has been working on this issue for over 1 year without success. Ford is giving me the run around saying that it is their job to get me to work with the dealer. They also told me to keep with the same service department because other dealers don't want to "fix" another dealers problems. While I like that they are going to give me a X plan pin if I purchase a new ford, I am having a lot of difficulty ever considering a new ford product. The other day I was looking at other makes and they were going to give me a great deal on a new one and a good price on mine for trade. Since I have a sport, I figure someone who is going to buy it likes to have a sport and I am sure the dealer was either going to put it out on the lot of wholesale so sooner or later someone was going to get screwed with a flawed a/c system and I just can't do that to someone who would most likely come to this site for help. For the cost they have already spent trying to fix this car, they should just replace everything such as the evaporator and compressor just in case and also give them the opportunity to check those parts to see what was causing the problem. Instead, I keep getting inconvenienced and jerked around. I never had problems like this with any other car I owned.

[FusionDiffusion]

This is stupid. It shouldn't be hard to figure this stuff out! You hook up the scan tool and read the evaporator temp PID compare it with the reading of a thermometer stuck in the center vent. If they're more than 5-10ºF different or the temp sensor is reading some crazy temperature then you know the evap sensor is the problem. If you've replaced the temp sensor and it reads the same as before, then you know the problem is with the wiring or the HVAC module and you go do your testing to rule the wiring out. You find and fix the problem with the wiring if that's the problem, otherwise you replace the HVAC module.

 

Not sure if you want to troubleshoot this more on your own or not (I can help).

[thefoeyouknow]

As a point of fact, the receiver/dryer IS integrated into the condenser, however, you wouldn't see this problem with any kind of condenser issue. I'll put this in bold: If I had a bucket of Fusion evap temp sensors I've pulled, there would be almost 40 in total, and every single one of them has been internally open, resulting in a reported evaporator temp of -40f which causes the AC to NOT work. These sensors only fail one way. I would really like to see a datalogger recording of this car's A/C PIDs. FusionDiffusion is correct, If there is an erroneous or suspected erroneous temp reading and the sensor is not responsible, then there is either a problem in the wiring, or a module. The PCM controls the A/C clutch, and reads the evap temp sensor. I really wish I could get my hands on this car.

[pcsgrp35se]

From what the Ford rep told me on the phone, the FSE's are having them change the condenser I guess because they think there is a blockage which I really don't understand. I would think that perhaps the evaporator which has gone a lot of freeze thaw cycles is at the point where the lines may have been crushed so it is freezing up. who knows. I am hoping that it is going to fix the problem. They tested out the harness and all the resistances were ok. They changed out the evap temp sensor I think now for the third time about the only tings left are the a/c computer or the compressor. If I set the temp on 70deg and put the blower speed on manual at the highest setting, it takes a very long time for it to stop blowing cool air as well as air from the vents. I also noticed the other day it was very humid and just before I lost air flow I got a lot of misting form the a/c ducts. I have to think that ford is spending a huge amount of money trying to fix this issue. It is a shame because the car runs great otherwise and I have been very happy with it.

[thefoeyouknow]

The evaporator is working. Freeze thaw cycles will not harm it, it's designed for that sort of thermal cycling. The fact that it still freezes solid should be evidence enough of that.

 

An odd sort of question to ask, but has anyone tried swapping the AC clutch relay? I was just thinking about the possibility that the points inside could be contaminated, causing them to stick together and causing the PCM to be unable to shut down the compressor clutch, in turn resulting in extremely low pressures on the suction side, and eventual evaporator freeze-up.

Edited August 12, 2013 by thefoeyouknow

[pcsgrp35se]

^{I don't know if they did that but I do recall that they said that the compressor was cycling . I do recall that the compressor did cycle when they manually forced it to do so by disconnecting I think the sensor wire. I also noticed that if I leave the temp at 70 and keep the blower on high, I can hear the compressor kick in and out. When they call me to have me take the car in, I will ask if they checked the compressor clutch to see if it is ok. WOW did I just get the phonecall of my life ! ! ! Called service department and asked for the service writer who has been responsible for me and who was supposed to call me Friday or today to let me know that the parts are in and they told me that he no longer worked at the dealership ! ! ! No wonder they didn't call. You just can't make this stuff up any more.}

 

^{Just got off the phone with the service department. They want me to bring in my car Friday to change the condenser. According to them, they have about 250 cars to fix in a recall so Friday is the soonest they can get my car in. They tell me it is only a few hours to fix. So much for my priority, after all, they have been trying to fix this since last august. Hopefully this time they will get it fixed}

Edited August 12, 2013 by pcsgrp35se