[ImperialCrown]

Unplug the A/C compressor connector is the only way I know of.
The compressor is run in defrost mode at around 40 deg F and higher to remove moisture from the air. Something to reduce window fogging.

 

[Bob Lincoln]

Hi, Does anyone know how to defeat the A/C compressor when the heat position is selected ? Geo M

A/C compressor should NOT be running in the Heat position - only in Defrost, A/C and Max A/C modes.

 

[george w]

According to the owners manual on my 2005 Liberty the a/c compresser does run in the heat positions. It does not run continously but cycles for short periods. The manual indicates that this is for dehumidification. I simply unplugged the compressor to prolong the compressor and clutch life during the cold weather months when dehumidification isn;t really needed.

 

[ImperialCrown]

You may find that some dehumidification is necessary as the cabin warms up in colder weather. You can simply reconnect the compressor if you needed to.
Clear windows are a safety concern. You have to be able to see around you.
I don't think that by disabling the compressor that you will significantly give it a much longer life. Compressors should generally last the life of the vehicle, but I agree that any A/C service is expensive if they have to reclaim and open the system.
Radiator cooling fans used to run as the vehicle warmed in cool, damp weather so that owners wouldn't see steam rising from the grille. For many, the first thought was overheating. You wouldn't see the steam with the fan on. Like the running compressor, it's in the control software and can't be changed. The controls are smart enough not to run the compressor in freezing cold ambient temperatures that could harm it.

 

[MoparNorm]

You may find that some dehumidification is necessary as the cabin warms up in colder weather. You can simply reconnect the compressor if you needed to.
Clear windows are a safety concern. You have to be able to see around you.
I don't think that by disabling the compressor that you will significantly give it a much longer life. Compressors should generally last the life of the vehicle, but I agree that any A/C service is expensive if they have to reclaim and open the system.
Radiator cooling fans used to run as the vehicle warmed in cool, damp weather so that owners wouldn't see steam rising from the grille. For many, the first thought was overheating. You wouldn't see the steam with the fan on. Like the running compressor, it's in the control software and can't be changed. The controls are smart enough not to run the compressor in freezing cold ambient temperatures that could harm it.

Yes.
The A/C working in conjunction with the defroster dramatically cuts down on defrosting time, by drying out the air as the defroster heats the glass.
Compressors, when running, self lubricate, I run mine, when ever the car is running, regardless of outside temp and Ive never had a failure.

 

[george w]

On my other cars the snowflake switch on the HVAC controls will enable or disable the compressor clutch. Not so on my Liberty. When the HVAC control is in the heat ( not defrost ) positions. Irrespective of the snowflake switch being on of off, the compressor will cycle several times a minute ( like every 10 seconds or so ) when in the heat modes. This has got to shorten the life of the compressor clutch and have some affect on gas mileage.
If you look at repair histories of this generation of Liberty's the a/c clutches are a high trouble area.
They should have designed the HVAC system where the compressor function was controlled by the snowflake switch in all modes like in most cars. This way you can decide if you need a/c or dehumidification or if you just want heat or air circulation.