Automotive Air Conditioning Information Forum (Archives)

jed1154 on Fri June 14, 2013 1:37 PM

Year: 2005
Make: Ford
Model: F-250
Engine Size: 6.0
Refrigerant Type: R134
Ambient Temp: 100

They replaced the compressor, and associated parts. It still is not functioning correctly. For the most part it works 'ok', but not 1700 bucks worth of OK. It was 100 degrees yesterday, with the AC on recirc and set to its coldest setting, it will blow at 48 degrees while driving. When you come to a stop, the temperature drops to 40. When you start driving again, the temperature goes up to 50 or higher, then eventually settles back to 48. I was sitting at a stop sign yesterday and my digital thermometers showed 39.5 degrees with 100 degree ambient temps.

It is very inconsistent. If I put it on 'outside' air, then the problem is amplified. In fact, when you take off, the temp will go to 68 and fog up the thermometer. I don't know if its overcharged, undercharged or a pressure switch thats messed up. In the shop, every single time they have told me that the 'pressures are where they should be'...and in the shop, that might be true. What can I do before I lose my temper, slam the dealer survey and start attempting to get a refund on the costs? I dont like doing other people's jobs, but it looks like im going to have to here.

James89dx on Fri June 14, 2013 3:39 PM

Wait a minute, you're complaining about 40 degree vent temps at IDLE in 100 degree heat? And of course the air is warmer with the vent open.

So overall, in 100 degree heat, you have cent temps between 40 and 50ish degrees? I don't see the problem.


Edited: Fri June 14, 2013 at 3:41 PM by James89dx

jed1154 on Fri June 14, 2013 3:49 PM

Really? Thats normal? Its normal to be colder at idle and have temperature swings of 25 degrees at random times but mostly when accelerating?

I have had this truck since it was brand new. It will throw a 39-41 degree vent temp CONTINUOUSLY in 100+ degree heat. It is not doing that now. Its a problem and im trying to help a 'pro' figure it out before I throw the whole dealership, service advisor and tech under the bus and pay MORE money for an independent shop (what I should have just done in the first place).



Edited: Fri June 14, 2013 at 3:55 PM by jed1154

James89dx on Fri June 14, 2013 4:21 PM

Typically, it's the opposite. For example my old Civic ('89 model on which I completely re-did the system last year with all new parts other than the hard lines) can't even hardly do mid 50's at idle. If it sits idle more than a few minutes it will start blowing 65+ degrees at the center vent. Once I start driving it it can work down to low 40's at the center vent and will fluctuate between there and low 50's. If I get stuck at a long stop light in 100 degree heat it'll get up into the 60's.

All of my cars over the years have generally had a 10-15 degree variation overall. I've never had any vehicle stay within a 2 degree vent temp under all driving conditions.

Regardless, if your system performs differently than how it did previously then I suppose that's an issue.

Edited: Fri June 14, 2013 at 4:23 PM by James89dx

Dougflas on Fri June 14, 2013 4:33 PM

Do you know if they have looked at/checked the blend door motor and flaps?

mk378 on Fri June 14, 2013 4:56 PM

If by "accelerating" and "taking off" you mean flooring it, many systems are set up to drop out the compressor during wide open throttle to get the most horsepower to the wheels.

If the clutch gap is too wide, the compressor may not always re-engage immediately when it is supposed to-- This can happen on a new compressor. It is also possible for the compressor relay to become intermittent.

jed1154 on Fri June 14, 2013 9:59 PM

To my knowledge they have not checked blend doors or flaps. Since it didnt start doing this until after they worked on it, I doubt its that. It has had pressure switches replaced for similar issues right after accelerating. I am not talking about WOT. This is just regular accel. I suspect the clutch is not engaging because the only way I can sort of duplicate the issue is to turn the 'ac' part off. The temp goes up and exhibits the same symptoms, so Im suspect of a switch or something. Can they be fickle and cause these sympstoms? Arent those replaced when they do the accumulator? What about orifice tubes? Can the 'wrong' one of those cause these issues? I dont think the tech is lying...when its at idle, I bet the pressures and everything look great, because its working as its supposed to. There is no way to evaluate it 'on the road' though.

jed1154 on Mon June 24, 2013 1:06 AM

Here is the MAIN issue, if I cruise down the road, the temperature settles on say 60 degrees. It pretty much stays there. When I stop for a light, the temperature immediately drops 3-4 degrees, and may creep back up a little. When I take off, the temperature immediately starts rising 5-10 degrees. After a little driving, it eventually settles back to 60 degrees. Ideas?

NickD on Mon June 24, 2013 7:14 AM

Can only guess without pressures, if over charged or restrictions, HPCO circuit can be cutting off the compressor. What about your dealership, do they have the proper recovery and a charging station and a guy that knows how to use it?

Know in my neck of the woods, would be a cold day in hell before I take any of my vehicles to my dealerships. And when it comes to electronic knowledge, would have to give them a zero. What's a thermistor? A what?

iceman2555 on Mon June 24, 2013 9:57 AM

Going to throw out a problem solution we encountered a few weeks ago. Perhaps it will help, perhaps not.

First what happened to the OE compressor (why was it replaced) and what associated (?) parts were replaced.

A tech called in a with a similar problem. Late model Ford that he had replaced the compressor on, flushed, new orifice, new accumulator, and recharge. His recharge equipment was a bit out of date, but should have charged the system correctly.

After several minutes of conversation and a few basic thermal diagnostic procedures, it was determined the condenser was restricted. The catch was that the condenser problem did not present itself until RPM was increased. At idle the system performed to his satisfaction, however, when engine PRM was increased, performance seemed to diminish.

At idle the temp drop of the condenser was within or border line acceptable ranges, however, the increase in RPM resulted in a severe difference of inlet/outlet temps. The discharge line became extremely hot.

The conclusion was that the condenser was restricted, but why did this condition not present itself at idle.

The installer replaced the condenser and the problem was resolved. Unfortunately we were not able to obtain the condenser to determine a possible cause, but conclusions were that the condenser was marginally restricted, thus the operational temps appeared to be satisfactory, however, the increase of compressor performance at an elevated RPM and the associated restriction resulted in a drastic increase of discharge pressure/temperatures and a restriction of refrigerant flow, thus the decrease of performance.

Not sure if this is the same issue that you are experiencing, but it is very similar.

A good simple test would be to arrange for an assistant. Start the vehicle, allow to idle with the AC operational for app. 5 minutes. During this time, periodically touch the discharge line (compressor to condenser), DO NOT GRAB, simply touch the line. It should be warm to slightly hot. If the line temp is HOT and the temp continues to increase, this is a indication of a restriction within the condenser. Increase engine RPM...if the line becomes extremely HOT...(do not want to touch again) once more this is a indication of a restricted condenser. Check the evap inlet and outlets also, they should be the same temp. If a noticeable change occurs at the same time the discharge line begins to over heat, this also could point to a restricted condenser.
It appears that this vehicle has a Pressure Relief Valve in the compressor hose/manifold assembly. Check to insure that this valve has not released. Tattle tale marker will be missing. If this valve beings to purge when the PRM is increased....then the condenser is probably the cause.

Post back with additional information.
Good luck

-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

jed1154 on Tue July 02, 2013 6:22 PM

My OE compressor was replaced because at idle it was not cooling. He said it is not outputting the correct pressures.

Its there now and they swear up and down it works right. I have a series of photos that show the temperature at 45 degrees, then 2 minutes later at 65 degrees, then 1 minute later back at 45 degrees. Its been there THREE DAYS. I will be requesting my money back after this so that I can take it to a shop that can fix it. Im dumbfounded how a dealership tech cannot figure it out. I mean, he doesnt go to school for 6 years to know everything about all the vehicles int he world. he goes to school for a LONG time for one make of vehicle and one system. THE AC SYSTEM. I dont see how this is so hard.

jed1154 on Wed July 03, 2013 6:20 PM

The associated parts replaced were accumulator and orifice tube. Also replaced fan clutch for whatever reason. The service idiot drove it too, said its normal for the temperature to go from 43 to 65 on acceleration since the compressor is cycling. Im going to take it to an independant shop and not the dealer hack. Probably dispute the original charge on my card if possible and file a BBB compaint since I gave them 2 chances to fix it. Im convinced the AC tech should be placed in the tire rotation department and stay far far away from AC work. So, im out nearly 2k, it works 'ok' and I still have to pay someone else to fix it right. Not much else I can do.