AC Cycles With Switch in Non-AC Positions

[boutym]

Got this 2000 Ranger back in Feb and the AC didn't work. Compressor wouldn't engage. Suspected it hadn't been serviced since new and last week took it in for a check. Leak check was good and they found the system was near empty. Charged it up and works like a champ except for one thing.

The compressor will cycle on and off even when it's supposed to be off. If I go to the AC or Max AC position it works. Turn to the other positions and it cycles on and off (randomly). Turning the selector to OFF will stop it, but as soon as I go to any non-AC position it will again start the cycling on and off.

 

[fraxinusalba]

Both my Explorers do this. Its designed to periodically cycle the compressor to maintain lubrication. However, I believe the AC does not cycle on the dash vent only position on my Explorers.

 

[Pensa]

My 95 does that, I think it's designed that way.

 

[boutym]

I could understand it coming on every now and again, but this one comes on and stays on sometimes for a while and then shuts off. In other words, I wouldn't consider this a 'normal' cycling of the compressor. It also does it in any switch position except for off and AC/Max AC.

That being the case, I'll have to track down what component controls this function.

 

[hworksinc]

That's normal behavior. I can't remember the details, but I believe the A/C compressor should cycle in the floor/dash and floor/defrost position to maintain humidity and temperature. In the A/C, Max A/C and defrost positions, the compressor should be on continuously. In the floor only and dash only positions, the A/C compressor will not cycle.

I may be wrong about the floor only position - the compressor may cycle, but I'm sure it doesn't cycle in the dash only position.

It's all designed to lower humidity and maintain the temperature you set - if you raise the temperature, the compressor will cycle less frequently.

 

[96eb96]

That's normal behavior. I can't remember the details, but I believe the A/C compressor should cycle in the floor/dash and floor/defrost position to maintain humidity and temperature. In the A/C, Max A/C and defrost positions, the compressor should be on continuously. In the floor only and dash only positions, the A/C compressor will not cycle.

I may be wrong about the floor only position - the compressor may cycle, but I'm sure it doesn't cycle in the dash only position.

It's all designed to lower humidity and maintain the temperature you set - if you raise the temperature, the compressor will cycle less frequently.

Yep, perfectly normal except in the "Vent" Or arrow to the head position. Also it keeps the compressor shaft seal nice and lubricated when you don't use the A/C. Sometimes the A/C helps with defrosting. At temps under about 40 deg, the compressor will not function.

 

[boutym]

Ok. I'll play with it more. Never though they'd get that sophisticated with a truck in 2000. It can actually be a little annoying, especially with the 3.0 motor.

Is there a humidity/temp sensor someplace? Seems odd that if this is what they are doing with the design that it would randomly cycle unless it has a way of knowing the humidity and temp.

Thanks for all the feedback.

 

[96eb96]

Ok. I'll play with it more. Never though they'd get that sophisticated with a truck in 2000. It can actually be a little annoying, especially with the 3.0 motor.

Is there a humidity/temp sensor someplace? Seems odd that if this is what they are doing with the design that it would randomly cycle unless it has a way of knowing the humidity and temp.

Thanks for all the feedback.

what do you mean randomly cycle? The A/C works by sensing pressure and cycling the compressor for certain intervals. This can be affected by temp, humidity, airflow over the evaporator etc. Nothing high tech here. Sometimes the compressor will never cycle, if its really hot its always on.

Does it also cycle on max a/c?

 

[boutym]

what do you mean randomly cycle? The A/C works by sensing pressure and cycling the compressor for certain intervals. This can be affected by temp, humidity, airflow over the evaporator etc. Nothing high tech here. Sometimes the compressor will never cycle, if its really hot its always on.

Does it also cycle on max a/c?

I don't believe it cycles on Max. I'll have to live with it a while longer to get a feel for it. Like I say, just got it serviced the other day, so not familiar with how it acts yet. Just found the cycling interesting and have never seen it happen (or noticed) with other vehicles I've owned unless they had true climate control.

 

[hworksinc]

Yeah - it is odd behavior. My parents thought something was wrong with their 2000 Focus when they got it - it behaves the same way.

As long as the compressor stays on (no cycling) when the switch is in the A/C or Max A/C position, then it means the A/C system is healthy. If it cycles in those positions, and it's above 40 deg F, then it may mean the pressure in the lines is low, or there may be something wrong with the clutch.

I drove a 2000 Ranger with the 3.0 engine for a while - I agree it does noticeably sap power. If you want, you could install a switch on the wire for the A/C clutch to manually disengage it. However, it is good to run the A/C occasionally like folks have said to keep the system lubricated.

 

[boutym]

Yeah - it is odd behavior. My parents thought something was wrong with their 2000 Focus when they got it - it behaves the same way.

As long as the compressor stays on (no cycling) when the switch is in the A/C or Max A/C position, then it means the A/C system is healthy. If it cycles in those positions, and it's above 40 deg F, then it may mean the pressure in the lines is low, or there may be something wrong with the clutch.

I drove a 2000 Ranger with the 3.0 engine for a while - I agree it does noticeably sap power. If you want, you could install a switch on the wire for the A/C clutch to manually disengage it. However, it is good to run the A/C occasionally like folks have said to keep the system lubricated.

I may put a switch in there for the times I'm pulling the trailer in the hills or need that extra boost when racing...

 

[96eb96]

I may put a switch in there for the times I'm pulling the trailer in the hills or need that extra boost when racing...

I know it A/C cuts out at wide open throttle to give max power.

 

[CDW6212R]

That is normal operation, but it is most annoying when the outside temps are not high enough to need AC. I noticed it the most in Winter, and vent is the only position that will not run the compressor.

 

[boutym]

That is normal operation, but it is most annoying when the outside temps are not high enough to need AC. I noticed it the most in Winter, and vent is the only position that will not run the compressor.

An example of engineering at its best. Kinda like how national heathcare will work with the gov controlling it...

 

[CDW6212R]

Ditto, I think if the goal was to run the compressor occasionally, a relay could easily turn it on automatically on start up for 20 seconds. Running it as often as it does when AC is not needed is too much.