Run AC in winter?

It used to be true that it was a good idea to run your AC every few weeks in the winter, just to keep the seals in good condition. I suspect this may no longer be needed due to improvement in materials, but I’d like to hear from someone who knows.

Yes, it is still a good idea.
Luckily, whenever you run the HVAC system on the “Defrost” setting, the A/C compressor is activated.
As a result, you have probably been periodically running the compressor even if you were not aware of it.

Yes, it is still a good idea to run it in the winter every once in a while.

Other than new refrigerant, I can’t think of any major improvements in A/C technology in the past 20 years.

It is the oil on the compressor shaft seal that actually keeps the refrigerant in the system. If this is not replenished on a regular basis the oil film can be breeched and refrigerant will leak out.

The same holds true for the other seals (o-rings and hose connections) in the system but the compressor shaft seal is the only one that moves consistently.

Hope this explains the recommendation sufficiently

Luckily, whenever you run the HVAC system on the “Defrost” setting, the A/C compressor is activated.

That is NOT true on all cars…Some cars YES…NOT all.

On my 4runner…my wifes Lexus…past Nissans and Accords…the AC would NOT turn on when the defrost was turned on…On some Honda’s like the Civic it would turn on.

I stand corrected.
The A/C compressor has run when the defroster was activated on every car that I have owned since 1981, including a Chevy, a Ford, a Honda, and 2 Subarus.

Now, if the OP will disclose the make of his mystery vehicle, perhaps we can tell him what the situation is with his specific model.

Some cars have a sensor outside that will not allow the compressor to run below a certain temperature. That way you can defrost the windshield in the winter without the AC kicking in.

"That way you can defrost the windshield in the winter without the AC kicking in."
No, it’s so that the AC system will not be damaged by trying to operate with too low of a pressure (because of the low temperature).
The heater will always overpower the AC. There is no need to turn the AC off to be able to get hot enough air to defrost the windshield or heat the interior. Most auto-climate control systems run the AC compressor all of the time. (Even when it is very cold outside, it is usually warm enough under the hood for the AC to run some of the time.)

OK, I’ll buy the low pressure/low temperature statement, but why would you need to use the AC compressor during the winter? That makes no sense. I’ve worked on Fords that have the temp sensor right behind the grill. I’ve had to jump them to check the AC compressor when it was too cold outside.

It’s used to remove the moisture from the air for more effective defrosting.

Personally, I liked making the choice myself better.

Actually, the humidity has to be removed for effective defogging. But yes, the reason for running the AC is to de-humidify the air.

I suspect it’s true for more cars in recent years than not.

Well, have we decided that some cars run the compressor when the defrost is on and others do not?

Technically true, BLE, but does your owners’ manual differentiate between defogging and defrosting???

The point is yours, however, based on the actual difference in goals.

Yes, we have. Some cars do it, some cars don’t.