Anybody know A/C's?
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Senior User
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From: southeat Ga.
Anybody know A/C's?
My A/C works fine at slow speeds and sometimes I still have it up to 60 mph but it usually it stops blowing cold above 50 mph and always stops before I hit 70. It's fine around town but sometimes under acceleration when the rpm's get a little high (merging with oncoming traffic) it'll stop blowing cold breifly. Any ideas here? A/C shops are too proud of their time to go to one unless there's no way to fix it myself. Thanks.
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From: Stephensville WI
Sounds like you are low on refrigerant, although it could also be a pump going south on you. Since you're not complaining of any odd noise I would rule out the pump.
Quick fix, try adding some R-134a to the system and see how it works.
Interdynamics Arctic Freeze 22-oz. R-134a Refrigerant : JC Whitney: Auto Parts & Accessories
But, if the R-134a is low and this fixes it, you still have a leak you need to repeair. Some stop-leak might help.
CASTROL® R-134A LEAK STOP AND DETECTOR - JCWhitney Auto Parts
Quick fix, try adding some R-134a to the system and see how it works.
Interdynamics Arctic Freeze 22-oz. R-134a Refrigerant : JC Whitney: Auto Parts & Accessories
But, if the R-134a is low and this fixes it, you still have a leak you need to repeair. Some stop-leak might help.
CASTROL® R-134A LEAK STOP AND DETECTOR - JCWhitney Auto Parts
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Joined: Apr 2006
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From: Austin, Texas
Most vehicles have a switch or something that automatically cuts out the A/C at WOT, so the A/C cutting out when accelerating sounds pretty normal. The other symptoms, not so normal.
It is easy to give your refrigerant (R-134A) a little bump: most auto parts stores have a little kit for it. I'd do that first, see if helps. You probably do have some kind of problem though, the refill is a temporary fix.
c.
It is easy to give your refrigerant (R-134A) a little bump: most auto parts stores have a little kit for it. I'd do that first, see if helps. You probably do have some kind of problem though, the refill is a temporary fix.
c.
Hook it, I'll pull it.
Joined: May 2007
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From: Grand Lake, La.
This is news to me.
Hotshot
Joined: Jan 2004
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From: St Louis
Whoa! Don't touch that refrigerant can! You are NOT undercharged.
If you were undercharged, the system would NOT work properly at lower speeds.
Look for something simple, like an excessive clutch air gap that is allowing the clutch to slip, a VERY common Ford problem.
Ford has used at least two different schemes to control the AC clutch over the last few years. The simplest controls the clutch directly by the pressure cycling switch. No relays involved.
Another scheme uses a relay to energize the clutch. The relay is controlled by the PCM. The cycling switch is an input to the PCM and the PCM's programming determines when to (or not) energize the relay and consequently the clutch. Various conditions include (but are not limited to) engine temperature and throttle load.
Since there is nothing unique about the SD system relative to the more basic model, you can take advantage of most of the information in the HVAC sub-forum. You'll also find REAL A/C people there who know how the system is supposed to work and can provide correct information.
Steve
If you were undercharged, the system would NOT work properly at lower speeds.
Look for something simple, like an excessive clutch air gap that is allowing the clutch to slip, a VERY common Ford problem.
Ford has used at least two different schemes to control the AC clutch over the last few years. The simplest controls the clutch directly by the pressure cycling switch. No relays involved.
Another scheme uses a relay to energize the clutch. The relay is controlled by the PCM. The cycling switch is an input to the PCM and the PCM's programming determines when to (or not) energize the relay and consequently the clutch. Various conditions include (but are not limited to) engine temperature and throttle load.
Since there is nothing unique about the SD system relative to the more basic model, you can take advantage of most of the information in the HVAC sub-forum. You'll also find REAL A/C people there who know how the system is supposed to work and can provide correct information.
Steve
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From: Wake Forest, NC
I second the clutch concern. Could be slipping, belt issues etc. Any a/c that gets WORSE with speed usually has a mechanical problem not a refrigerant problem. The exception may be if the evaporator is icing up due to blockage or slightly low refrigerant level. Next time it does it, try turning the a/c off at speed, then back on. If it starts to get cold, then stops it may be icing up.
More Turbo
Joined: Aug 2006
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From: W. Wisc
Without a set of gages, you are diagnosing in the dark. They are cheap and readily available. Make sure they are R134a before buying (local Craigslist, ebay, or new) and connect them. Then post the results in the AC forum. The answer will ususally be pretty obvious with the gages readings and observed behavior.
But don't just start adding refrigerant until you know you need it.
But don't just start adding refrigerant until you know you need it.
Junior User
Joined: Feb 2006
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From: Michigan
The "under accelleration" part could indicate a vacuum problem with the blend door unless it is electronic. What year and model?
Oops! Just saw that in your sig.
Blend is electronic, but vent/defrost/floor switching is vacuum. Is your cold air coming out the defrost ducts when this happens?
Oops! Just saw that in your sig.
Blend is electronic, but vent/defrost/floor switching is vacuum. Is your cold air coming out the defrost ducts when this happens?
New User
Joined: Jun 2006
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From: Middle TN
My `97 F-250HD does that @ accelleration when on max cool.It blows through the defrost ducts,as soon vacuum returns,it blows through the dash.It`s the vacuum actuator in the passenger foot compartment,on the bottom of the air/heater plenum,easy to get to.Use a vacuum pump to see how much vacuum it pulls to activate the actuator,then check vacuum comming from the "switch".Ford dealer has quite a few part #`s for this so,get the # from the old one & take it w/you.-Ream
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From: southeat Ga.
Well I checked on this stuff tonight and am more confused. I ran up to 75 and it still blew cold through the vents like it's supposed to so after I stopped at the RR tracks I took off as hard as I could run it all the way to 96 and the a/c never missed a lick.
It stayed cold and blew through the dash vents the whole time, I waited for the truck to reach full operating temperature so everything was normal. The only thing I can think of now is that it does it on sustained runs (at least 5-10 minutes) because I didn't have very far to go tonight. Any thoughts?
It stayed cold and blew through the dash vents the whole time, I waited for the truck to reach full operating temperature so everything was normal. The only thing I can think of now is that it does it on sustained runs (at least 5-10 minutes) because I didn't have very far to go tonight. Any thoughts?
More Turbo
Joined: Aug 2006
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From: W. Wisc
Get a set of gages. Really. They are $70-80, and if you look for used ones you can get them cheaper. Make yourself more useful to your friends by being able to test their AC. They'll help you move that new fridge or keg-o-rator in :-) Check it out vs the shop manual specs. (See the SD tech folder for links to the manuals online). Then you'll know if it is in the AC system, or elsewhere. Never turn down a good opportunity to get a new tool...
It may also be a vacuum leak in/to the actuators that is the issue as RudyF6 noted. When it goes bad - what does it do? Does it go warm, or does the air go to a different vent position like the deforster or floor. If it goes warm, then it is likely the blend door. If the air goes somewhere else then it is one of the other actuators under the dash. Do you have the EATC or the manual AC?
It may also be a vacuum leak in/to the actuators that is the issue as RudyF6 noted. When it goes bad - what does it do? Does it go warm, or does the air go to a different vent position like the deforster or floor. If it goes warm, then it is likely the blend door. If the air goes somewhere else then it is one of the other actuators under the dash. Do you have the EATC or the manual AC?
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From: Albuquerque, NM.
Dont ever put any product with stop leak into a AC system.It will clog the system. It will clog the condenser,and the expansion valve/orfice tube, and it usually doesnt do the compressor any good.