Dakota Durango Forum banner

A/C compressor always running?

10K views 9 replies 6 participants last post by  99v6Dakota 
#1 ·
on my 99 Dakota whenever the HVAC is on any position other than off the compressor cycles? Is this normal?

If it isnt, any ideas how to stop it? My gas milage is poor with the 5.2 to start with, this cant be helping.

Thanks
-Dave
 
#2 ·
probably not normal. I think the HVAC switch is a vacuum switch since it's primary function is to control which vents are open/closed which all operates off engine vacuum. maybe there's a vacuum operated relay that's stuck closed, turning the compressor on all the time?
 
#3 ·
Does it run all the time? Or does it just cycle every so often....... if it runs all the time, then you could have either a bad ambient air temp sensor,switch. etc. Could be as simple as a bad ground (bad grounds wreak absolute havoc with electrical systems. You could also have a stuck relay (which i would check first).......if it is cycling all the time on you, then pull the A/C compressor clutch relay out of the power distribution box for the time being.

on a side note, most systems are designed now to cycle when you put the HVAC into defrost mode, to help eliminate dried out seals and seized up compressors due to lack of use in winter months.....
 
#7 ·
sort of....


it's not to prevent seals from drying out from non-use, its to dry the air out so you're blowing dry air onto the windshield which helps pull the water vapor (fog) off the glass.

you know how in the summer time your AC drips water out? that's because the air blowing over the cold coils cools the air down, and any water in the air will condense, fall out of the air and form water drops that eventually drip out onto the ground, giving you cold dry air. this air then goes over the heater core and heats back up. now you have hot dry air to help defrost/defog your windows in the cold winter months. the heat helps melt any ice that formed on the outside, but the dry air blowing on the inside helps keep the water vapor that forms fog on the inside of your window clear. this fog comes from your breathing, rain that dries off your coat when you get inside, snow on your shoes that melts and evaporates into the air, etc.
 
#5 ·
so it should cycle all the time whenever the HVAC switch is on? it cycles every 10-20 seconds regardless of outside temps.

Its not really hurting anything, I was just curious. I only has 60k on her, and I try and keep up with everything that may be going wrong.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top