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AC Cold at Idle/Not as much at cruising? Pages: 12Last

jed1154 on Mon May 06, 2013 12:19 AM User is offline

Year: 2005
Make: Ford
Model: F-250
Engine Size: 6.0

Just had my AC serviced for it not cooling at idle, but cold when driving. It has 100k miles. They determined the compressor needed replacing, so it was replaced at the dealer, with all associated parts. Now, it works much better at idle...in fact, at idle with 90 degree ambient temps, I can get vent temps of 40 degrees, no problem. However, when you start driving, that temp goes to about 48-50. Ive never had this kind of flip flop problem so I have no idea if its an issue or not. When the truck was working a while ago, 40 degrees driving and 45 at idle would be about right. Is this 'normal' for a new compressor? Should I haul it back? Is it normal for it to be colder at idle than when driving? I was charged for 32 oz of refrigerant. It has a 12 month warranty if its something that should work itself out.

Edited: Mon May 06, 2013 at 12:31 AM by jed1154

Dougflas on Mon May 06, 2013 4:14 AM User is offline

Was the cycling switch changed? These are a known problem on Fords. If not the switch, the system may be undercharged. This can cause freeze ups and/or short cycling at high speeds. I would have it rechecked. 32 oz is 2 lbs of freon. Check your labl under the hood and see if youir application calls for 2 lbs.

I checked and your system takes more than 32 oz. You could be up to 6oz short on charge.

Edited: Mon May 06, 2013 at 4:36 AM by Dougflas

jed1154 on Mon May 06, 2013 10:20 AM User is offline

BAH! You're right! The label on the truck under the hood says 2lbs 10oz.

That's more than 6oz low. That is the amount that is supposed to go in it correct? I wouldn't have thought to look under the hood, but I sure as hell expect an AC technician to be able to figure it out. I figured when considering replacing a compressor, that adding the proper amount of refrigerant based on the little sticker with giant letter would be the easiest part of the. :/

I was told that they may have 'recovered' some and re-used it. I don't know if that sounds right or not.

Edited: Mon May 06, 2013 at 11:49 AM by jed1154

jed1154 on Tue June 10, 2014 8:00 PM User is offline

Will the cycling switch cause the problem of the compressor cutting out when normally accelerating? It does this a lot but when you are cruising it works great. I had it back to the dealer twice. I took it to an independent shop once. Supposedly neither could duplicate the problem. It doesn't give problems cruising or idling so much. I do not know if the low pressure switch was replaced and I cannot recall if this was a problem before repair. I know that switch has been replaced once and for 10 bucks I'm thinking about giving it a shot myself. If the techs can't figure it out with all their schooling the. I have nothing to lose except refrigerant and at that point they can evac and refill.

Dougflas on Tue June 10, 2014 9:26 PM User is offline

cycling switch should have a schrader valve under it so no real loss of refrigerant. You might check and see if your vehicle has a wide open throttle switch.

jed1154 on Wed June 11, 2014 12:11 PM User is offline

Im almost certain it has a WOT cutout, but i don't do WOT ever really. Ill try the switch thing. I would like to just wait until it fails totally so they can diagnose it, but that could take forever.

Dougflas on Wed June 11, 2014 7:11 PM User is offline

jump the switch. It still can be bad even if throttle is not wide open. Be careful.

ascalise on Fri June 13, 2014 6:57 PM User is offline

Similar to what my truck is doing that NO ONE can figure out.

jed1154 on Tue June 24, 2014 7:40 PM User is offline

No luck with yours?? Wish I could find a shop in Katy that had a decent tech that was willing to appreciate the problem and make an effort to fix it. Its not rocket science for them if they want to do it right.

Edited: Tue June 24, 2014 at 8:00 PM by jed1154

jed1154 on Wed June 25, 2014 12:22 AM User is offline


I have posted here SEVERAL times about this truck. It was recently completely serviced with a new compressor and whatever goes with that. Since then, it has been back to that shop twice, and another shop once and somehow no one can find a problem. MAYBE it just happened to not do it when they looked...or they are just lazy. I know the second tech pretty much kept it for two days and said "well, it feels like its cooling OK"...that was his professional opinion. Either way, Im going to set out on a DIY course to troubleshoot this myself. I have a set of gauges I can use but have no experience or clue about what I'm doing, which most likely puts me on par with the techs I have unfortunately had to deal with. My gauges came from ACKITS I think, they are MasterCool?? They have red and blue quick disconnects and are brand new. Bought them years ago but never used.

The truck cools inconsistently. When I set everything to manual, sometimes it blows at 40, sometimes it blows at 50-60. Its completely inconsistent and seems to be related to engine RPM at times. I have not replaced the cycling switch, but I have one on hand. However, today, I noticed while sitting still that it suddenly stopped cooling well....out of the blue as it does, so I opened the hood and looked around. One thing I noticed is that there is a cylinder shaped object on the passenger side with a pressure port on it. Its where the cycling switch is. Anyway, I noticed while it wasnt cooling that one big line attached to compressor was ICE COLD and the other big line going to firewall was warm. This MUST mean something, but I don't know what. Is this perhaps useful info? Im pretty certain that most of the time both of these lines are ice cold.....or pretty close to it.

Thanks for any insight.

jed1154 on Wed June 25, 2014 12:29 AM User is offline

Quote
Did you happen to notice if the compressor was engaged at the time?


I did not notice, but Im assuming it pretty much has to be running if anything at all is cold, yes? Ill try to notice next time.

When I watched it the other day, at idle or even with high idle, the compressor never shut off. Sure i have noticed it cycling during cooler temps though.

jed1154 on Wed June 25, 2014 12:50 PM User is offline

Do you think it would be prudent to hook up my gauges and get some actual numbers for people to work with? Is this safe(ish) for a DIY dude? Teh issue is almost nonexistent in 'recirc' mode.

Edited: Wed June 25, 2014 at 2:59 PM by jed1154

jed1154 on Fri June 27, 2014 10:09 AM User is offline

Just replaced the LPC switch. No luck. I put it on 'vent' and after driving, the vent temp will be 50, and after a few minutes of idling it will go up to 70 and get really humid. Teh compressor is running while doing this. Not sure. Im going to put gauges on it. Screw it. Then I need to find a tech thats not a hack.

mk378 on Fri June 27, 2014 11:14 AM User is offline

Leave the A/C off and set it for unheated outside air. Monitor the vent temperature during the trip. If the heater is kicking in, it will warm up the air and that effect of course also fights the A/C.

jed1154 on Fri June 27, 2014 12:21 PM User is offline

Thats an idea. That might actually point me to a potential blend door issue, right?

jed1154 on Fri June 27, 2014 2:57 PM User is offline

Where can I find pressures and specifics for this vehicle? Are all pressures the same for R134a? What should they be if ambient is 80? 90?

jed1154 on Fri June 27, 2014 6:59 PM User is offline

I put my gauges on it.


ambient temp is 91 out. Vent temp is 60, vent air, not recirc.

At 1500RPM

L:45->47
Hi: 275-300

These continuously rose and fell in a loop over and over. Compressor never shut off. I can only assume the last shop refilled to proper weight.

bohica2xo on Sun June 29, 2014 10:52 PM User is offline

Duct tape.

Put the gauges on it, and duct tape them to the outside of the windshield. Then go for a drive.

Post the results.

.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

wptski on Sun June 29, 2014 11:16 PM User is offline

Quote
Originally posted by: bohica2xo
Duct tape.

Put the gauges on it, and duct tape them to the outside of the windshield. Then go for a drive.

Post the results.
.
Hmm, how would you route hoses to close the hood? They do have a iManifold from Stride Tools which syncs to a mobile phone right now aimed at HVAC work.

mk378 on Sun June 29, 2014 11:42 PM User is offline

Go straight out gap at the back of the hood instead of at the side. Have someone else drive so you can pay full attention to the pressures.

wptski on Mon June 30, 2014 8:18 AM User is offline

Quote
Originally posted by: mk378
Go straight out gap at the back of the hood instead of at the side. Have someone else drive so you can pay full attention to the pressures.
In the past I've had a hard time even using small diameter clear plastic hole for monitoring vacuum let alone gauge hoses. Might be vehicle dependent?

jed1154 on Mon June 30, 2014 10:37 AM User is offline

So, the pressures as shown look good?

bohica2xo on Mon June 30, 2014 11:12 AM User is offline

Jed:

The pressures don't look too bad for 1500 rpm in the driveway. The pressure swings were probably your fan cycling. Forgive me but I am on a tablet right now - does your f250 have the PCM controlled fan?


The road test pressures can help sort out any air flow issues.


-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

jed1154 on Mon June 30, 2014 12:48 PM User is offline

Yes, fan is PCM controlled, and that was something they replaced as well when the original service was done. When it kicks in, you know it. I have not noticed it kicking in, but the AC issue shows up in teh morning with temps in the low 80's and the evening with temps in the mid 90's. Also, the condenser in the front is nearly spotless. Ill try to duct tape it to the window. How much refrigerant am I losing every time I hook up gauges? Appreciable amounts?

I can't get my head around what could possibly cause this. Even when you get to a stop sign, the AC gets a little colder breifly, then when you take off, it starts to warm up. Then after cruising, it will slowly cool back down until the next stop.

I think the pressure will help daignose.

Edited: Mon June 30, 2014 at 12:53 PM by jed1154

bohica2xo on Mon June 30, 2014 1:54 PM User is offline

The 6.0 with the electric fan clutch has a dual gate switch. While the symptoms are different, you can look at this thread for some added information:

F350 6.0L thread

You have noted that the fan does not run up much. It probably should run at the pressures you posted for the 1500 rpm test. Check the service manual for switch pressure points.

As far as losing refrigerant when connecting gauges, yes you lose a little. If you have done a lot of connection cycles, you can add back a couple of ounces.



-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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