Air conditioner question: Does it make any difference if


#1

Which is worse on an air conditioner, wear and tear wise? Is it worse on the air conditioner to the fan on the highest setting, and less cold air or the highest cold setting and a low fan speed?


#2

I am not an air conditioner expert but I have a logical answer that may apply. Putting the cold air on high is probably the maximum load you could put on your air conditioner. The fan speed being high or low shouldn’t make any difference since all the fan does is disperse the cool air quickly or slowly.


#3

It’s easier on the compressor if you run the circulating fan faster, but much less comfy in my opinion.


#4

It really makes no difference. Its like putting a towel over a light bulb to darken the room or taking the towel off. When you turn the air conditioner on, the compressor will cycle on and off to maintain the refrigerant charge. Turning the temp down or up does not change this but only introduces hot air from the heater to warm the air or less hot air to make it cooler. Turning the fan up or down again makes not difference except possibly a micro amount by warming the condenser. So the only thing that matters is if the system is on or off. Anything else doesn’t matter except for your comfort.


#5

Might make a slight difference, but a comfortable temperature is where you stop and so, same answer.


#6

With the fan on high the system is passing more hot air , transferring more heat to the refrigerant, so I suppose it could be argued that the compressor would be required to spend more time compressing, perhaps placing more wear and tear on it, and even using up more gasoline since that’s what’s turning the compressor. The mileage difference is measurable and even noticeable on the old, less efficient systems of my youth, but not as much on modern systems. Modern compressors usually last the life of the vehicle, so the difference in wear & tear isn’t measurable in any meaningful way.


#7

Makes no noticeable difference in my opinion. Your A/C compressor runs in the wintertime when you’re using DEF and/or BI-LEVEL.

Just my 2 cents and the opinion is unscientific but I think a lot of a compressor failures are due to several factors.
That most leaks are around compressor shaft seals, the trend in mounting compressors down low where refrigerant oil has a tendency to pool when the A/C is inoperative, and recharging which may often involve replacing the refrigerant but not the compressor oil which has weeped out along with refrigerant past the shaft seals.


#8

No significant difference. Do what is most comfortable.


#9

When the AC is turned on, the compressor maintains a certain pressure. Whatever speed the fan is running at has no bearing on the compressor…

Tester


#10

Interior fan speed has no bearing on A/C compressor wear and tear. The biggest thing that adds load and strain to the compressor is heat. Heat dramatically raises the internal pressures of the system, sometimes as much as doubling the load of the compressor. That additional load will cause more wear and tear on the compressor.

For the longest compressor life I recommend you not use the A/C if the outside temperature is above 70 degrees. OK, that’s just not going to happen. For long compressor life, have your mechanic check to make sure the system is fully charged, that the condenser and radiator are clean and free of debris, and that the cooling fan(s) are working at full speed.


#11

Tester
When the AC is turned on, the compressor maintains a certain pressure. Whatever speed the fan is running at has no bearing on the compressor…

Well, my thinking was that a higher circulating fan speed tends to make occupants feel cooler, so the hot/cold adjustment might be set a bit warmer, thus requiring fewer on/off cycles for the compressor…no?


#12

No.

There are few CCOT AC systems on the road these days.

Most AC systems use an expansion valve to maintain the compressor pressure.

So no matter the temperature or the fan speed, the expansion valve will keep the compressor pressure constant.

Tester


#13

No, doesn’t matter where you set the temperature. Its not like your house thermostat.


#14

Well…my manual AC Hondas have an expansion valve, but also cycle the compressor to prevent evaporator freeze-up. At max “temp” (dial all the way in the blue), and low fan, the car is comfortable. At max fan, it would be too cold, so I’d have to dial the temp down (mix hot air with the cold), but the compressor stays on longer with each cycle (if it cycles at all). In the first case I get max economy and comfort but cycle the compressor more. In the second case, I get less economy and annoying air blasting at me, but cycle the compressor less. I choose the first case for economy and comfort.


#15

@insightful: why in the first case would you have more economy? I do not understand the implication of bad or good as to whether the compressor cycles more or less. Please explain.

@ auto-owner, everything else being equal, is it goo or bad for the compressor to have more or less on/off cycles?

Currently I have the air set at high cool and low fan, and keep the fan low all the time and just adjust the cool to where it feels comfortable, but I do fiddle with it to keep the right balance. I do not like the noise or blast of air in my face with the reverse settings, but my inquiry was related to what is best combinations for the wear and tear on the compressor.


#16

It doesn’t make any difference to the compressor, but it will wear the fan out faster.


#17

“It will wear the the fan out faster.”

Care to explain?

Tester


#18

The blower motor will wear the brushes out faster at the highest speed.


#19

Okay? What does that have to do with the AC?

Tester


#20

“…why in the first case would you have more economy?”

In the first case, the compressor is ON, say half the time. In the second case, maybe all the time. Compressor ON more = using more gas to power it. It may be that the first case will shorten the life of the compressor (more ON-OFF cycles vs more continuous operation which machines usually like better), but, as we both have found out, it is more comfortable.