Where I'm heading with this is my 2000 Accord has a button to turn ac on and off also it has a button for fresh and recycled air, which is very nice. I have full control over it. So I'm wondering if anyone put a button or a switch at least for ac, so when you have it on defrost in winter then ac compressor doesn't run and not only that heat is not the greatest like we all know it just would make sense to not have ac on. No I know when there is moisture ac helps defrost in that case you can always turn it on but for the most part I'd be leaving it off. 

And not sure on recycled/fresh air door if it could be put on a switch. I don't see why not for ether just haven't looked that hard in to it. 

Some day it will be like in a plane with all the switches and guages.

Would be surprised if your ac doesn’t run on defrost regardless of switch 

8 hours ago, Dieselfuture said:

Where I'm heading with this is my 2000 Accord has a button to turn ac on and off also it has a button for fresh and recycled air, which is very nice. I have full control over it. So I'm wondering if anyone put a button or a switch at least for ac, so when you have it on defrost in winter then ac compressor doesn't run and not only that heat is not the greatest like we all know it just would make sense to not have ac on. No I know when there is moisture ac helps defrost in that case you can always turn it on but for the most part I'd be leaving it off. 

And not sure on recycled/fresh air door if it could be put on a switch. I don't see why not for ether just haven't looked that hard in to it. 

Some day it will be like in a plane with all the switches and guages.

I've been meaning to post about this as well. If I am correct (and very well could not be) the PCM controls the AC compressor.  I have thought about installing a switch that will  interrupt the power going to the clutch.  For you guys up north it must be frustrating to have that cold air from the AC when you don't need or want it.

 

The recycle/fresh air is controlled by vacuum. I'm assuming there is a way to control this but am not sure how.

 

Thanks for bringing this up and hopefully we can figure this out.

 

L8tr

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7 hours ago, Royal Squire said:

Would be surprised if your ac doesn’t run on defrost regardless of switch 

I was hoping to wire in the switch to the AC compressor clutch like @SilverMoose mentioned, that way we can turn it on at any gate selector position. So even if it's selected to the floor or vent/floor, I still want to be able turn it on or off at will. I don't know why Dodge ever went to this design, Simplicity perhaps almost like having no locking hubs and a cad on front axle. 

The PCM turns the A/C on by grounding the A/C compressor clutch relay when commanded by the A/C heater control switch and the A/C low and high pressure switches are closed and grounded.  

 

You could install a switch between pins 1-C3 and 22-C3 of the PCM.  This would give anytime control with the added benefit of low/high pressure cut off if needed.

Thank you @IBMobile I'm going to marinade it for a while and see what else comes from this thread, but when I get board again I'll be doing this as I like to be in control of then the compressor is running. And for the blend door fresh/recycled I can probably use a vacuum solenoid like some did on CAD to have 2 wheel low.

Personally I would like to have a full on and off switch so A/C can either turned on in any position or forced OFF and any position. Some times you would like to drive through an area of heavy smoke or dust and want to keep your heat going so you'd flip over to MAX A/C now the outside air is turned off but the A/C compressor is running. Kind of like you like to run DEF or floor DEF without the compressor coming on. Like in the morning before the engine is warmed up so you get super cooled air. 

So has anyone attempted this yet, I've been fixing other thing but now catching up. I'd like to know also better way to deal with this hvac system. Is @IBMobile suggestion a best way or is there other ways like @Mopar1973Man is thinking, or are you guys talking about same thing. 

After looking this over again pin 22 at C3 is grounded through the AC controller and not give full anytime compressor control.   The easiest way would be a single poll three position switch installed with the common wire being the dark blue/orange from pin 85 of the AC compressor clutch relay.  Position one of the switch the wire going to Ci pin 1 at the PCM, position two is open circuit and position three the wire goes to ground.

 

In number one position there is normal AC control.  In number two position the AC compressor will not turn on.  Number three position the AC compressor is on all the time.  

What @IBMobile suggests is a way to have A/C compressor in any position or being able to shut off the A/C compressor in all positions then the 3rd position follows factory setup. That would be kind of cool to have. That is a problem I've never liked about Dodge HVAC setups the early 2nds allowed for that but later 2nd gen's when back to the old school setup. Now if we had a way to control recirc or fresh air door but that is a vacuum control. 

Just playing around with mine i noticed the compressor is on in all positions except the dash only position. Would that not give what you are? Or is my truck just weird for some reason?

Compressor modes - MAX A/C, A/C, BiLevel, Floor-DEF and DEF.

 

No Compressor modes - Vent or Floor. 

 

Outside air - All other Modes except MAX A/C.

 

Recir Air - Only MAX A/C. 

So who's going to be first to make this work and simplifie it  I like the idea of 3 position toggle switch that IBMobile suggest, and rec/fresh can be delt with later.

Edit 

Which diagram above will work with 3 position switch? And is there a colored one someplace @Mopar1973Man  ?

I'm not too strong in this field, but should be able to manage once I get going. 

Edited August 24, 20186 yr by Dieselfuture

 

The first diagram, 8W-42-5.   

2 hours ago, IBMobile said:

 

The first diagram, 8W-42-5.   

Can you hand draw a picture for a dummy like me. I would appreciate it.

Edit 

I think I'm understanding what we're doing here, I don't think that there is a need to cut any wires ether. Just pull pin 85 out of ac relay and extend the wire to the switch then run another wire back to relay and one to ground. 

Am I thinking correctly? 

It will be a lot easier to cut the dark blue/orange wire at either connector C-130 (which is the connector at the PDC) or the c-1 connector at the PCM.  You can then run the two wires into the cab and attach them to the switch with the third wire going to a grounding point.   If you try to disconnect the wire from terminal #85 of the ac compressor relay you'll find it to be a big PIA in the PDC.

 

Be aware the forced on mode might have an issue. Being the hi and lo pressure switches are now locked out. It would be possible to operate the compressor beyond the lo point and freeze up the evaporator or possibly operate above safe 450 PSI limit which is no explosion issue.

 

Now if it was force on using the dash wiring now the pressure switches would be in the loop.

1 hour ago, Mopar1973Man said:

Be aware the forced on mode might have an issue. Being the hi and lo pressure switches are now locked out. It would be possible to operate the compressor beyond the lo point and freeze up the evaporator or possibly operate above safe 450 PSI limit which is no explosion issue.

 

Now if it was force on using the dash wiring now the pressure switches would be in the loop.

So how do we do that, I was just looking under the hood now, good thing I'm not as fired up as I used to be on these things, I'd have it done already lol.

To get the benefit of the hi and lo pressure switches tap into the light green/white wire behind the AC heater control.   The wire coming from C134 would be #2 on the 3 way switch.  Ground wire would still be #1 on the 3 way switch.  The wire going in to pin #2 at the back of the AC heater controller will be #3 on the 3 way switch.  

 

 

@IBMobile Would it make sense to just have on or off, no factory stuff. That way you're able to turn ac on on any blend door position or have it off. Why even set it up to work like it was designed. I guess my question is will this mod work with simple on off toggle switch on that same wire, or does it have to be 3 way. Just want it simple and effective. 

Yes it will work with an on/off switch but you lose the simple factory switching for those that are AC operationally challenged.    

 

The red line shows the original ground path.  When you cut the light green/white wire your just changing the ground path (blue line).

 

 

 

 

Edited August 26, 20186 yr by IBMobile