Air Conditioning Problem

Just recieved the last of the parts I needed to do the lower intake manifold gaskets. I just got to busy. Put another 3000 miles on since I discovered the problem. Now its getting worse. While I was looking at he air conditioning on my sons Blazer I discovered mine want working on the Windstar. 96 3.8 LX. It had been working a few days earlier. The only thing that changed was the fact I replaced the bulbs in the electronic instrument cluster. You have to remove the bezel around the radio and the panel below the steering column and the 2 screws holding the padded panel above the cluster. I dont remeber there being any wiring for the air that had to be removed. The clutch on the compressor does not engage. The freon level was fine blowing cold a few days ago. Any ideas? Thanks

The relay that drives the A/C compressor clutch is inside the Constant Control Relay Module (CCRM).
Mine became weak......and caused the compressor to cycle on and off quickly......and was the last thing that needed doing after the new evaporator coil was installed, and the system was charged up again.
From what I understand, the relay is activated by the A/C Cycling Switch, A/C Pressure Cut Off Switch and the PCM.

Now, the bezel around the radio would be getting you around the heater controls.
My '96 activates the A/C in all settings except the off and vent settings.....
You might double check to see if the controls switch between the defrost, floor, vents, etc to verify that those controls are intact....in case something became unplugged.

My electrical diagram shows the electrical control for the A/C going into the selector (AC, HEAT, Defrost, etc) through Fuse 21 (10 amp), which is listed as hot when the ignition key is in ACC or ON.
The blower motor power from Fuse 36 (30 amp) which is listed as hot when the ignition key is ON.

From the Selector switch (powered from Fuse 21 via a Pink with Black Stripe wire) a Purple wire goes to the A/C Cycling Switch.

Another Purple wire goes from the A/C Cycling Switch to the A/C Pressure Cutoff Switch Pin C.......a normally closed relay.

A Black with Yellow Stripe wire goes from the Pressure Cut-Off switch Pin D to both the PCM pin 41 and the CCRM pin 21....serving as the power to drive the A/C Compressor clutch, when the A/C Clutch relay is activated......to put the power from Pin 21 to Pin 23.

CCRM Pin 23 delivers the power (+) to the A/C clutch through a Pink with Light Blue Stripe wire.
A Grey with White Stripe wire provides ground from the A/C compressor Clutch back to the CCRM pin 16 (ground) and common with Pin 15.

Pins A & B on the Cut-Off switch are a normally closed switch......Tan with Green Stripe to the PCM on Pin A, and a Black with White Stripe to Pin B.

A Pink with Yellow Stripe wire goes from the PCM pin 69 to CCRM pin 22 for the A/C Clutch relay field activation, with CCRM Pin Pin 15 Black with White Stripe wire serving as ground.

PCM controls the activation of the A/C clutch relay in the CCRM....via pin 22

The A/C cycling and pressure switches can supply or interrupt the main driving power to the A/C clutch relay contacts.....

wiswind
Thanks for the quick reply. I have not checked any fuses yet. I will pull the bezel off tommorow and check for disconneted or broken wires. The fact it was working a couple of days ago and no problems ever leads me to believe it is related to the bulb replacement. I really wanted to get started on the intake manifold before anymore wear occurs. Do you know is the low cut out a normally open or closed switch? Would the ccrm go bad that quickly? I believe I can hook 12Voltz and a ground to the connector on the compressor and it should run, that way I would know if it got cool it was related to something other then the compressor and lack of freon correct? Thanks

You want to be very careful about the connecting the 12V directly to the compressor...as this would bypass the protection of the high pressure cut-off switch.
The high pressure cut-off switch is normally closed, and opens when the pressure gets too high....415-445psi
The contacts will open again at 220-280psi.

The high pressure cut-off switch has ANOTHER set of contacts that close when the pressure is 285-315psi, turning the radiator fans on at HIGH speed.
These same contacts open at about 250psi.

There is a pressure relieve valve that is supposed to vent the refrigerant to the atmosphere at 450psi

The A/C cycling switch monitors the pressure in the evaporator core and is OPEN whenever the pressure in the evaporator core is 22 - 28psi.
The contacts CLOSE when the evaporator core pressure reaches 40-47psi.
This ends up maintaining the evaporator core temperature at just above freezing......preventing the evaporator core from developing ice on it.

In above freezing conditions, the A/C cycling switch contacts should be in the closed position.

wiswind
Thanks for the quick reply. I have not checked any fuses yet. I will pull the bezel off tommorow and check for disconneted or broken wires. The fact it was working a couple of days ago and no problems ever leads me to believe it is related to the bulb replacement. I really wanted to get started on the intake manifold before anymore wear occurs. Do you know is the low cut out a normally open or closed switch? Would the ccrm go bad that quickly? I believe I can hook 12Voltz and a ground to the connector on the compressor and it should run, that way I would know if it got cool it was related to something other then the compressor and lack of freon correct? Thanks

Not to discount what Wiswind said about high pressure, but, you can accomplish this task easier by unpluging the clutch cycling switch atop the receiver dryer and "shorting" it. I put a small nail in each side of the connector (+/-) and connect the two with a wire with alligator clips on the end. If you are going to take 12v directly to the clutch, you can do so by back probing the hot lead only, as ground is there as long as you do not unplug it.

I would however rather see you get a set of guages and measure the freon charge directly.

best of luck

Wiswin
I decided to bypass the AC cycling switch. I know its a normally closed switch so I jumbed it out and eveything works fine. Im surprised it happend when it did. It was just a coincedence. Ill order one when Im done with the manifols gaskets. Thanks

busboy4
You must have been typing when I was. I will have to replace the switch and recharge correct?

busboy4
You must have been typing when I was. I will have to replace the switch and recharge correct?

Hi

No, to change that switch if you need to, you just unscrew it. It has a schrader (sp?) valve underneath that will hold the freon in.

busboy4
Thanks Ill give it a try after I finish my manifold gasket change.

i have a question?? i have a ford windstar which a mechanic replaced the air conditioning compressor for me and charged me $300.00, now, 5 months later, the new compressor is making the same grinding noise again. Although the noise was gone and the serpentine belt was replaced, i was not aware that the system should have been blowing cold air. Should the mechanic have recharged the system when he replaced the compressor?

i have a question?? i have a ford windstar which a mechanic replaced the air conditioning compressor for me and charged me $300.00, now, 5 months later, the new compressor is making the same grinding noise again. Although the noise was gone and the serpentine belt was replaced, i was not aware that the system should have been blowing cold air. Should the mechanic have recharged the system when he replaced the compressor?

Hi

In a word, yes. Did your A/C work at all after the compressor replacement? Normally, assuming the A/C system has no leaks, the system is discharged of freon, the work completed on the components i.e. compressor replacement and then the system is vacuumed of air/moisture (and leak tested) with a vacuum pump and a freon charge is added. For your van somewhere in the 21/2 to 31/2 pound range.

Unfortunately, if your van simply had the compressor changed out and the system closed up without being vacuumed or recharged I would advise you to have the accumulator/dryer changed now (it would likely be saturated with moisture) as well before the system is vacuumed and charged. Sorry.

How did this turn out? What was the cause?