Is the low pressure / compressor cycling switch adjustable? A/c cycles on highway

[masospaghetti]

My other vehicle (pontiac Fiero) has an adjustable low pressure switch. Is there any adjustment here? And is the switch replaceable without discharging the system?

On the freeway, the a/c works, but it cycles even though the air blowing out of the vents isn't really cold (on A/C MAX). I figure it should stay on 100% duty cycle until the cabin is really nice and cool.

Thanks all.

 

[Maniak]

I've never seen one that was adjustable.

Every one I've ever seen screwed onto a shrader(sp?) looking valve. That means you can remove it without venting the system.

Normally, when I see low pressure on the low side it is caused by low system pressure. Once the compressor really gets going the low side drop enough to trip the low pressure switch.

It might be normal for you system to occasionally turn off when heading down the road. From what I've seen this is to help keep the system from freezing up.

~Mark

 

[masospaghetti]

Is it normal for the compressor to cycle on the highway, even if the cabin is still warm?

On most vehicles I've owned, the compressor would only begin to cycle once the cabin temperature had fallen significantly (when in recirculation, of course).

 

[bobflood]

It might be normal for you system to occasionally turn off when heading down the road. From what I've seen this is to help keep the system from freezing up.

+1 on this. However, most of the time if a compressor is doing a "short cycle" the system is low on refrigerant. That would be the first thing to check.

 

[my98nnj]

It shouldn't cycle off the low pressure switch. If that is indeed what's happening, the system charge is low. There is a temperature sensor in the evaporator that will cycle the compressor to maintain evaporator temp and prevent a freeze up.