A/C Compressor is always on?

[exploration1997]

Okay, so in panel, floor, panel/floor, and A/C, the A/C compressor cycles for 10 seconds and takes a break for 5 seconds, and repeats this. Is there a relay or something that's gone bad? I'm 99% sure the A/C compressor is only supposed to be on in A/C and MAX A/C. What's wrong here?

 

[DUNE RCR]

Mine does the same thing as well and has since I've bought the truck. I don't know the exact reason for why it does this but have been told it does it to help with condensation. Makes sense to me so I ignored it, until about a year ago, I wired in a kill switch to the compressor to shut it off when I don't want it to run.

 

[koda2000]

Okay, so in panel, floor, panel/floor, and A/C, the A/C compressor cycles for 10 seconds and takes a break for 5 seconds, and repeats this. Is there a relay or something that's gone bad? I'm 99% sure the A/C compressor is only supposed to be on in A/C and MAX A/C. What's wrong here?

the short answer is for you to read your owner's manual. I believe it says the a/c will run in any position (except VENT) if the outside temp is above 55F. it has to do with removing moister from the air. if, for some reason, you don't want it to run unplug the compressor.

 

[exploration1997]

the short answer is for you to read your owner's manual. I believe it says the a/c will run in any position (except VENT) if the outside temp is above 55F. it has to do with removing moister from the air. if, for some reason, you don't want it to run unplug the compressor.

Does it run only at partial power unless the A/C is on? Because the thing is, sometimes I simply want fresh air coming in. Also, A/C wastes gas, so I only want the compressor on when I actually need it.

 

[koda2000]

Does it run only at partial power unless the A/C is on? Because the thing is, sometimes I simply want fresh air coming in. Also, A/C wastes gas, so I only want the compressor on when I actually need it.

there's no such thing as "partial power" for the a/c. it's either on or off. if you just want fresh air, use the VENT setting. that's the button on the EATC system. i'm not sure what it's referred to as on the system with knobs.

if you want to be able to control the a/c compressor at any setting, I guess you could add an ON/OFF switch on the compressor's power wire. you get cool evenings where you live (NH) but where I live I have the a/c going non-stop from about May through October, so the ability to turn off the compressor never crosses my mind. during the winter, it really helps in the DEFROST setting.

 

[exploration1997]

there's no such thing as "partial power" for the a/c. it's either on or off. if you just want fresh air, use the VENT setting. that's the button on the EATC system. i'm not sure what it's referred to as on the system with knobs.

if you want to be able to control the a/c compressor at any setting, I guess you could add an ON/OFF switch on the compressor's power wire. you get cool evenings where you live (NH) but where I live I have the a/c going non-stop from about May through October, so the ability to turn off the compressor never crosses my mind. during the winter, it really helps in the DEFROST setting.

Actually, I was wondering if I could rewire it so that the only time the A/C comes on is A/C, MAX A/C, Defrost, and Defrost+Floor. How hard (if even possible) would this be?

 

[Flash]

Actually, I was wondering if I could rewire it so that the only time the A/C comes on is A/C, MAX A/C, Defrost, and Defrost+Floor. How hard (if even possible) would this be?

Easy, interrupt the power to the ac clutch and install a switch.

 

[Flash]

there's no such thing as "partial power" for the a/c. it's either on or off.

With the knob system at least there's an A/C and a Max A/C setting.
My XLT had a leaking blend door and the A/C would only cool on Max. So that's partial.
I think ordinary A/C turns off under load, I'm not sure.

 

[koda2000]

go buy a good quality toggle switch (NAPA). find a place to mount it. run a wire (of suitable gage) from the switch out through the firewall to somewhere near the a/c compressor. unplug the wire connector on the a/c clutch and determine which is the power wire and which is the ground (usually the ground wire is black).

actually, as I think about it, I suggest you interrupt the ground wire with the switch, rather than the power wire. that way you only need to run one long wire out to the compressor from the toggle switch. you can run the other side of the switch to any convenient ground inside the cab. doing it this way, you don't have to add a fuse, or worry about having a short in the future. when you don't want the compressor to run, turn the switch OFF. if you wire the switch this way (read the note below) you would cut the ground wire near the a/c clutch connector and attach the wire from the switch (be sure to leave yourself enough wire to work with). the other end of the ground wire (the end going back into the harness) would no longer be used.

note: I'm not sure if the a/c system turns the compressor on/off through the GROUND or POWER side. determine that first. as long as it's the power side (meaning the ground is constant) follow the instructions above. if the ground side turns the clutch ON/OFF then you'll need to run 2 wires and interrupt the power side. if you do this, be sure to add an in-line fuse nearest the power source.

 

[exploration1997]

Easy, interrupt the power to the ac clutch and install a switch.

I'll do that only as my last option. I'd prefer to just rewire it so the A/C only operates as indicated above.

 

[koda2000]

With the knob system at least there's an A/C and a Max A/C setting.
My XLT had a leaking blend door and the A/C would only cool on Max. So that's partial.
I think ordinary A/C turns off under load, I'm not sure.

that's not really "partial" operation. the only difference between a/c and a/c max is whether the heater is blocked off or not and whether the fresh air vent is closed. the compressor continues to run the same in either setting. there's a WOT relay that turns off the a/c temporarily when you floor it.

 

[Flash]

Ok. I had a Toyota that had some sort of power saving AC setting, I know it turned off if it idled for a long time; just what you need when you're stuck in traffic.

I thought the Exp might have had something similar.

I had a vacuum switch installed in a Falcon I used to have, I set it to turn the AC off if I took off from standstill or highway overtaking.

 

[Flash]

I'll do that only as my last option. I'd prefer to just rewire it so the A/C only operates as indicated above.

Er, we basically said the same thing.

 

[alohamonte]

Isnt the real reason for the continuous on/off cycle is for self lubrication in order to greatly extend the life of the compressor?

 

[SoNic67]

Okay, so in panel, floor, panel/floor, and A/C, the A/C compressor cycles for 10 seconds and takes a break for 5 seconds, and repeats this.

If it short cycles like that (seconds) your freon pressure is low. You either need to add some of check for leaks. Or both.

Isnt the real reason for the continuous on/off cycle is for self lubrication in order to greatly extend the life of the compressor?

No, its not. Is written in the owner manual - is for de-humidification. If you pull in 'fresh air' with lots of humidity you will feel hotter than if the air was dry.
Also, the gas consumption is proportional with how long the on cycles are versus the off ones. So, turning the A/C setting lower, it will make the compressor cycle less frequent and use less gas. Don't turn it past red, it will add heat.
BUT: Turning the VENT setting on, will shut off completely the A/C compressor, there is no need to cut wires or disconnect connectors.
Just go read the manual.

Ok. I had a Toyota that had some sort of power saving AC setting, I know it turned off if it idled for a long time; just what you need when you're stuck in traffic.

So, I am stuck in traffic, no air moving past my windows, is 90F outside, 120F in the car and I don't need the A/C? Really? Your Toyota was defective, it was overheating probably in idle traffic.

 

[exploration1997]

No, its not. Is written in the owner manual - is for de-humidification. If you pull in 'fresh air' with lots of humidity you will feel hotter than if the air was dry.
Also, the gas consumption is proportional with how long the on cycles are versus the off ones. So, turning the A/C setting lower, it will make the compressor cycle less frequent and use less gas. Don't turn it past red, it will add heat.
BUT: Turning the VENT setting on, will shut off completely the A/C compressor, there is no need to cut wires or disconnect connectors.
Just go read the manual.

So, I am stuck in traffic, no air moving past my windows, is 90F outside, 120F in the car and I don't need the A/C? Really? Your Toyota was defective, it was overheating probably.

If it short cycles like that (seconds) your freon pressure is low. You either need to add some of check for leaks. Or both.

I thought r12 was freon? I have r134.

 

[SoNic67]

I thought r12 was freon? I have r134.

I used freon as generic name. It's R134.

 

[alohamonte]

It dehumidifies but the actual purpose is to keeps its oil circulating to prevent a dry start come summer.

 

[exploration1997]

It dehumidifies but the actual purpose is to keeps its oil circulating to prevent a dry start come summer.

But I don't understand - because the vehicles equipped without A/C would not start up properly. Is this true?

 

[koda2000]

1. about 10 secs on and 5 secs off doesn't sound like it needs any refrigerant to me. my '01 EB cycles about that often and it will freeze you out of the truck. it's the coldest a/c I've ever owned.

2. I don't believe that setting the TEMP knob nearer the red side has any effect on how often the compressor kicks in (or how long it runs). if the a/c is on, it's on. what causes the compressor to cycle is the HIGH pressure switch. this (pressure) in turn is effected by ambient outside temperature. setting the TEMP knob near/in the red just adds heater air so the a/c isn't as cold. if your truck has EATC, setting the automatic TEMP setting higher does the same thing.