2000 Ranger XL, 4wd, 3.0L V6 dual fuel engine. Bought used in 2006 with 73,409 miles. Today's mileage.......78,004. Yeah, 300-400 miles a year.

Cold air comes out of MAX a/c setting. Warm/hot air comes out of regular a/c setting. Took to local long time AAA/ASE shop. Invoice said all fixed. It was not. Same symptoms came on as I was driving home. I had looked under hood while running a/c in driveway. A "clunk" every five seconds or so...and front of compressor stops for 5 seconds or so and than starts spinning again. Rinse and repeat. MAX setting, no problem. Only in regular a/c mode.

Shop evacuated system and replaced shrader valves. Recharged with R134A. Invoice says "check duct temps" and "retest". I doubt it.

Going back to shop 5/29. Promises made to make things right. What do you think they missed and what do you think is actually wrong....and what fix is really needed ?

I know zilch about cars...and TIA for your replies.

 

Good thoughts from SHO89. Since you don't have AC service tools I found you a few pages that examine "clutch cycling time" that you may want to play with. Again it's based on current Ambient temperature. Time a full cycle (1 on & 1 off) and take a look at the appropriate chart to see if it's within Ford spec's. There are charts for each part of the cycle (on & off) to help determine what may be at fault.

 

Most likely, they only tested it in the MAX A/C setting since that's how system performance is supposed to be tested. They probably simply didn't check it in the "A/C" mode.

There are only supposed to be two things that are different between MAX A/C and A/C: 1) Vacuum is applied to the heater coolant valve in MAX A/C to cut off hot coolant flow and 2) Vacuum is applied to the air inlet duct vacuum motor so it closes and only allows recirculated air instead of outside air when in MAX A/C.

The compressor cycling you reported may be completely normal, it depends on the ambient temperature and the load on the system. We don't know if it was a mild 60 degrees or 110 degrees in the shade. That's actually important information.

Did you also observe the compressor clutch operation while in MAX A/C? If it also cycles much like in the A/C setting, then there's nothing wrong with the refrigeration portion of the system. While in MAX A/C, the refrigeration side of the system works exactly the same as when in the normal A/C setting.

However, since there should be no hot coolant flow in the MAX A/C setting, a faulty temperature blend door function would be masked and the air would only be cold for certain in the MAX A/C position. When set back to the normal A/C setting, a failed temperature blend function could cause warm/hot outlet air, depending on the position of the blend door at the time.. The thing you'd have to do is to check to see if the TEMPERATURE control works properly both when in one of the positions where A/C function is requested and then again in either the VENT or FLOOR position to see if that function works properly.

 

To me it sounds either like they missed a leak in the system and you're losing refrigerant, or the low pressure switch is faulty.

 

If any of those were faulty, the air wouldn't be cold in the MAX A/C position.

 

Cold doesn't mean it's cold like it should be, to the OP it could simply mean it's colder on Max than it is when drawing in outside air. The rapid cycling of the compressor is the result of a low pressure signal.

 

Maybe, maybe not. See prior discussion regarding ambient and loading conditions. Also, the OP stated "MAX setting, no problem. Only in regular a/c mode".

Until the OP clarifies specific details, we're just speculating.

 

Agreed, I too find it frustrating when they ask questions then abandon the thread when people invest time trying to help them.

 

That seems to happen more often these days than at any other time since I've been here. Honestly when I see a post that's someone's first time I shy away---typically they've stumbled onto FTE from a Google search for whatever symptom they believe they're experiencing.

But when those newbies abandon their own threads we regulars teach one another which isn't a bad thing.

 

No.....I have not abandoned my thread. Been testing out the various settings on the dash. Took lots of notes yesterday.....and will test everything again, today.... and report back tomorrow. Lots of confusing results. Thanks for the replies so far.

 

Hi again, I'm baaaaack. About 75 degrees out yesterday. Drove for 30 minutes and parked, engine running, in our drive. MAX A/C 40 to 50 degree air. After a while it dropped to 30-34 degrees. Am using my trusty $30 IR thermometer. Clicks and 5-10 second delay intervals. Regular a/c put out 120 to 140 degree air depending on which vents are selected. Left side fan speed dial makes no difference. Middle dial has red/hot markings on right and blue/cool on left. This dial was on blue/cool for the test. Right side dial has eight settings: max a/c.....a/c....outside air on face....off.....vent for face and feet....vent for feet....vent and defrost for feet....defrost. As you surmised, I am too inept to post a picture.

Asked my neighbor and he thought maybe a vacuum leak is affecting a blend door function....as mentioned in post #3. Nothing on shop's invoice mentioned checking the vacuum system.

Any help is much appreciated. Going back to shop on 5/29.

 

Your observations of the operation while in MAX A/C are completely normal. What you didn't report was a specific observation of what the compressor clutch was doing, if anything, when the MODE switch was set to any other position except MAX A/C. The switch is wired internally to enable compressor operation when in any position except OFF, VENT, or FLOOR. If the compressor does not operate in all of the other mode settings, you probably have a bad MODE switch. No need to post a photo of the switch, it's a standard item used for many years and a picture is in the owner's manual if anyone wants to look at it. You might wish to consult that so you have the correct understanding of what each switch setting actually means.

The blend door does not use vacuum so your neighbor's idea isn't applicable. You can verify the operation of the temperature blend function by testing it in any mode non-A/C mode (VENT suggested) by running it though its adjustment range and checking outlet air. A properly operating system would allow you to vary the outlet air temp from a bit above ambient to very hot.

 

I did some more testing yesterday and got both confusing and positive results. I cancelled my shop appointment and reset for 6 June. Need to test and make notes for the forum members to chip in...and for the shop, so they can narrow down the problem. Will report back in a day or two. Thanks for the replies, so far.

 

Still trying to do more testing. Got HOT here and my irrigation system needs some work. Might reschedule the 6 June shop appointment.

 

Rescheduled for 20 June.....