Late or Erratic A/C Clutch engaging

[searcherrr]

When I first start the van it takes anywhere from 12-20 seconds for the a/c clutch to engage after the Max A/C switch (coldest temp setting) has been turned on. This I know from driving any other car is not right. On the clutches 1st engagement it is very very harshly engaged and makes a loud clunk. Successive clutch engagements are smooth, but often very late and I say this cause it gets hot in the cabin while I'm waiting for it to come back on (usually when parked).

The compressor is a brand new Motorcraft with a new aftermarket clutch assembly that was working just fine on the previous compressor and moved to the new one. The system has been recently charged as you'd expect due to that maintenance. On the road the A/C runs perfectly, but in slow-go traffic or in park the clutch seems to do these weird late engagement things. Also note I have a brand new CCRM.

We can speculate and thats fine as always cause I welcome ideas, but I really want to hear as well from people who've already fixed this issue and what the fix was. One of the a/c (cycling or pressure) switches? A bad ground? Fuse blown? Relay?

Does removing the A/C cycling or pressure cut out switches require discharging refrigerant?

Let tha replies begin!

[searcherrr]

Damn, crickets. lol

[wiswind]

From the dash select......the wire goes through the A/C Cycling switch.....from there it goes through the A/C pressure cutoff switch, then to the CCRM (Constan Control Relay Module).....Pin 21
The clutch field connects to the ...Pins 16 (battery ground), and 23 (power from solid state relay).

The PCM drives the solid state relay for the clutch field through CCRM pin 22.

A/C pressure cutoff.......contacts CLOSED (power flows through) until pressure rises to 415-445 psi....then the contacts open.....causing the compressor to turn OFF.

When the pressure drops to 220-280 psi, the contacts for the compressor circuit close.....permiting the compressor to run again.....and the fan contacts open up.

In the SAME switch assembly is another set of contacts......normally OPEN....
At 285-315 psi these contacts close.....causing the radiator fans to come ON at HIGH speed.
At about 250 psi the contacts open.....causing the radiator fan HIGH speed operation to stop (unless being caused to be on from another cause, like high engine temperature).

The A/C Cycling switch is mounted on the side of the "suction accumulator / drier".....on a schrader valve (like a tire valve).
These contacts OPEN when the suction pressure in the dryer is 22-28 psi, preventing the A/C compressor from running.
The contacts CLOSE when the suction pressure reaches 40-47 psi permitting the compressor to run.
This prevents the A/C system from running in very cold temperatures.....like below, very roughly, 45 degrees.
It also prevents the plate and fin surface of the evaporator core (inside the blower box.....inside the passenger compartment) from operating below freezing......so it will not ice up.
The evaporator coils will be kept just slightly above freezing.

The A/C cycling switch is a simple unplug electrical wire and unscrew.......lubricate new switch with "Motorcraft YN-12b refrigerant oil"......or equivalent meeting WSH-M1C231-B

They don't mention if refrigerant will be lost if the pressure cut off switch is removed.....but I would expect that the schrader valve would prevent this for the cycling switch.
There are others who are experienced with this.

Cycling switch lists at roughly $19
Pressure cut off switch lists at roughly $45

I have a picture in the pictures that the link in my signature takes you to that will show you the location of BOTH the cycling and pressure switches.
I would expect that your '95 will be pretty much the same as my '96.

Now, my '96 A/C clutch does NOT engage right away when I start the engine.....it takes a little while before it happens....have never timed it...but not very long.
In any case.....it does not seem to happen right when I select an A/C setting.

[searcherrr]

Thanks again WINDSTAR GOD!!!!



Carl, I realize you have pictures of it, but have you ever replaced your cycling switch or pressure switch? What was your cause for doing so? When your clutch delays in coming on for the 1st engage.... does it do a big CLUNK/GRIND and only for the 1st engagement after having sat for a long time?

I called my trusted shop yesterday about this and they said when I remove the cycling switch there will be a little hiss and it'll stop... so there will be like maybe 1 or 2 seconds of pressure/refrigerant loss, but nothing significant if you unscrew it quickly I would think.

The accumulator is new and its making me wonder why they didn't replace the cycling switch with it when I was in my frenzy of "make van like new" with the barage of parts I bought to bring it up to date on TSBs and various weak spots. After all they were both there for 158k miles and A/C was/is used heavily here and they are both moving parts. I'm focusing on the moving parts for this problem at the time being. I really don't want to chase down wiring issues and I really don't see the point in checking the fuse 21 (10A) in the cabin cause if it was blown it wouldn't cut on at all which isn't my problem.

I did look in my Cd-ROM for this, but the closest I could find was "clutch doesn't cut on" and not "clutch takes a while to cut on". It doesn't so much bother me that it takes a while to cut on as it does that there is this huge CLUNK sound when it does cut on the 1st time.

Perhaps I should just lubricate the clutch assembly like I did on my car. I had never thought to do this before, but I was attempting to remove the clutch assembly on my car and it wouldn't budge for hell, so I ended up lubricating and cleaning it with 2 different bolt free-er-uppers and lubricant. Ever since then the a/c clutch has engaged beautifully and smooth cause its lubed and I removed A GREAT DEAL of debris from it. The new clutch assembly on the van of course wouldn't be dirty, but I bet it wouldn't hurt it to have a lil bit of lubricant.

Thoughts?

[wiswind]

I have never removed or replaced the cycling and pressure switches.
I had the accumulator replaced some years ago because of some deep rust pockets.

I would be carefull about adding lubricant to the clutch unit......I know that you know that you don't want to get lubricant onto the friction surfaces.....but it is hard to get it one place and not the other.
Lubrication on the friction surface could well cause a chatter.
A weak pull in force could also cause it.......or...as you had on the other car.....something keeping the moving part of the clutch assembly from pulling in firmly against the other side.

I would expect a "clunk" when it engages......but now chatter......wonder how strong the actual pull in is?.....

I think that the delay at first is to give the motor a chance to get running before hitting it with a big load.
The other thing that the PCM does is release the A/C clutch on full accelleration......to give you more power.
It also gives the engine a little bump in rpm when the clutch engages.
I notice this while cruising down the highway......the RPMs bump up (and the transmission's torque converter lock-up releases) whenever the A/C compressor engages.

[tripletdaddy]

My ac clutch on my windstar and taurus, with identical ac comp and clutch do make a louder clap or slap when first engaged, but does continue to make that sound while in use, just quieter. When driving, it may just seem to be less loud than the first time on. Actually, I'd expect the clutch to slap louder with a stronger coil and quieter with a weaker coil. A weak coil can't slap hard so it will be quieter.

What I'd do to figure out this delayed coil power on problem, is to track when the power comes on at the various points in the ac clutch circuit when turning it on inside. Go from component to component as Wiswind listed in order from the on control to the ac clutch to see if the power is delayed at any point. Do you have manual controls or the digital?

I'm not clear on what you would lubricate, but oil on the clutch plate and pulley plate would make it easier for it to slip. When the clutch does slip without you adding oil to it, brake cleaner can be sprayed on the clutch to clean it. It may be slipping while first starting, causomg the delay in cooling, but it wouldn't account for an electrical delay to the clutch.

Removing the switches doesn't require evacuating the system as there are check valves (schrader valves) behind them.

Wiswind, your pressure switch explaination is a bit misleading. The clutch cycling switch is what turns the ac on and off normally, turning it on at or above the 40s as you said, and turning it off when going down to the 20s. The switch will also not allow it to come on when the pressure is too low. typically due to a too low charge. The other switch you describe with the 200 to the 400+ pressures is the high pressure cutoff and high fan switch. It doesn't cycle the clutch, but protects the system from excessively high pressure by turning it off and allows it to come back on when the pressure drops down low enough at the respective pressures you stated.

[searcherrr]

Barring some electrical problem (which you guys know I've probably been chasing already with the fan cut-off near-stall problem) I'd be inclined to think that the cycling switch would be the most likely cause with the manual a/c switch itself in the cabin being the likely 2nd suspect. I state this based on the idea that they both are moving parts and the high-pressure switch I would expect to not have moved very much in the life of the vehicle. If I do this I'll probably just replace the cycling switch and see what it gets me and go from there.

Going to Pensacola Monday. It will be the first long trip the van has seen since the new engine debacle. Crossing fingers.

[wiswind]

Have a good trip.
The High pressure cutoff and cycling switches are in series.....either one being open will prevent the A/C from running.

As Tripletedaddy mentioned......the pressure cutoff switch (normally closed contacts) is a protection device to shut down the A/C compressor above a given pressure.
So you are correct in figuring that it would not be working too much.

The pressures that I listed above are from the AlldataDIY information.

I thought at some point that you might have replaced the Throttle Position Sensor.......
A very long shot would be a problem there.....indicating Wide Open Throttle.....which would cause the PCM to disable the compressor to give you more power.

If the delay is long....one could try jumping out the cycling switch (very temporary....while the hood is up and you are standing right there) to see if it causes the compressor to engage.

Of course....if the "charge" is not just right....it could cause an issue with the cycling switch.
I have never personally added or checked the R-134 on my own, so I have no experience there.
Until just a couple years ago, it was not permitted to buy even the R-134 without a license.

[searcherrr]

Thx again Clint.

The charge should be ok since I had them check it a 2nd time in complaint that it wasn't cool enough fast enough. In hot weather it struggles really to provide cool air. I'd say it feels cool enough just to keep me from sweating.

I just drove to Pensacola and back (235 miles each way) and the a/c worked fine for us though of course much better as soon as the clouds go in front of the sun. The delay is still there. I will probably try replacing the cycling switch at some point, but right now I have a Hurricane to watch out for and a cold to get well from.

If this fixes the issue I'll post back.

I have not replaced the TPS, but I wanted to a long time ago when I first thought the tranny issue was the TPS. I have a new one though I've never put it on. I'd like to, but I have been lazy about finding the right procedure. I know on my "car" I had to use a multimeter to set it right etc... I imagine there is something like that for the Windstar's too, but man I tell ya I just can't get excited or geared up to go reading more shit for this thing.