CCRM-Ref Containment Switch?

[3d914]

OK, got almost all the CCRM replacement relays wired up - ran out of heavy gauge wire.

Still missing one switch though. In the 3.0L PAVLIN schematic for CCRM it shows two wires (#17 & #21) going to the Refrigerant Containment Switch.

My page 23-7 from the EVTM shows #21 goes to EATC and #17 goes to the PCM at pin #31 (HFC).

1. Which is correct - EVTM or PAVLIN?
2. What/where is the EATC switch? I don't have the page 55-3 reference on my EVTM page.

Thanks.

 

[rubydist]

my Ford shop wiring manual shows:

pin 21 pink/light blue circuit 883 going to the a/c control relay feed
pin 17 dark green/orange circuit 198 going to the a/c high pressure switch

 

[pjtoledo]

what year are you using for the wiring harness?
I have a 92 and a 95 EVTM


in the 92 manual the command to start the AC begins in the ETAC and goes to the pressure/AC clutch cycling switch there is no refrigerant containment switch in my 92 schematic.. depending on the pressurein the system, the signal goes thru/or not/ the switch then on to both the ICRM , to turn on the AC field coil, and to the computer to bump up the idle turn the fan on, and other stuff

curcuit 348,pink wire leaves ETAC on pin 25, goes to pressure switch.
circuit 883 PK/LB wire leaves switch and goes to splice S147, then on to pin 21 ICRM and pin 10 on the computer.

the 92 manual does not show pin 17 at the ICRM,

the 95 manual shows circuit 198 DG/O coming from ICRM pin 17 as HFC (hi fan control) and going to either:

3.0 L engine= refrigerant containment switch as DG/O

or

3.2 L engine = powertrain control module pin 31 as curciut 639 on a LG/P wire, then comes back out of the PCM on pin 42 as circuit 198 DG/O
and goes to the refigerant containment switch. and then it gets complicated

reading more: in a 95 the refrigerant containment switch turns on a hi fan if pressure exceeds 375,,,,then it cuts the circuit to the AC clutch if pressure exceeds 430 psi

the 95 manual shows a R/Y wire, circuit 441 coming from the AC pressure cycling switch going to the refigrant containment switch.


this begs the question: what year setup are you using, as there are differences between the years.

wish I could scan this page,,too complex to describe easily.

Perry

 

[rubydist]

93 and earlier used R12, so no high-pressure cutout switch, 94+ used R134a and included a high-pressure cutout switch - therefore the wiring is different.

 

[3d914]

Thanks guys.

PJ, My setup is 95/MTX, but part of the problem is not all my harnesses are. If I gather what you're saying - "reading more: in a 95 the refrigerant containment switch turns on a hi fan if pressure exceeds 375,,,,then it cuts the circuit to the AC clutch if pressure exceeds 430 psi" and "AC pressure cycling switch" - the containment switch & pressure cycling switch are the same thing - correct?

I also noticed that some of my EVTM pages (copied from Tom's manual) are 3.0, some 3.2. Looks like I really need to get Section 23 (Engine Controls) of EVTM for 3.0 so I can wire this correctly.

 

[pjtoledo]

Thanks guys.

PJ, My setup is 95/MTX, but part of the problem is not all my harnesses are. If I gather what you're saying - "reading more: in a 95 the refrigerant containment switch turns on a hi fan if pressure exceeds 375,,,,then it cuts the circuit to the AC clutch if pressure exceeds 430 psi" and "AC pressure cycling switch" - the containment switch & pressure cycling switch are the same thing - correct?
I also noticed that some of my EVTM pages (copied from Tom's manual) are 3.0, some 3.2. Looks like I really need to get Section 23 (Engine Controls) of EVTM for 3.0 so I can wire this correctly.

I interpret the manual as those being two seperate switches, in the 95 manual.
the refrigerant containment switch is a safety, in normal AC operation its basically just another part of the wire.

by the way, the actual power to the AC field coil is pin CCRM/23 + , to the coil then back to the CCRM on pin 16 -,,,,,,all the above stuff is the control circuitry to tell the CCRM AC relay to turn on.

so, in simplified form you could:

have an AC switch on the dash, goes to AC pressure cycling switch, goes to a power relay that energizes the AC field coil.
this does not address regulating the temperature


confusing enough?

 

[rubydist]

I believe that the containment switch is the high-pressure switch, while the cycling switch is the low-pressure switch.

the idea is that the clutch cycles off when the low side gets too low, which allows the pressures to stabilize, and the clutch cycles off when the pressure gets too high, thus containing the refrigerant by preventing an explosion.

 

[pjtoledo]

more or less. I'll add a few boring details.

AC cycling switch: closes at 45 PSI increasing. opens at 25 PSI decreasing. Thats an exact quote from the 95 book. remember this is the suction line, if the AC is running and building the high side, this line is being pumped down. this also is a cold ambient temp lockout. if its cold the gas shrinks and overall system pressure drops below 25 the switch is open and the AC won't work

there is another note box on page 55-3 for the AC clutch cycling pressure switch,,, "shuts off power to the A/C field coil if there is low suction pressure" thats the cold ambient temp lockout.


the line from the cycling switch goes thru the normally closed contacts in the containment switch
the line for the HFC goes thru the normally open contacts of the containment switch.


the Containment switch, again a direct quote: "Operates the high speed electro drive fan with the refrigerant pressure over 325 PSI. high speed fan turns off when pressure drops to 325 PSI. Also opens A/C clutch circuit at 430 PSI. Closes circuit at 250 PSI"

the containment switch is on the high pressure side,

all this is from the EVTM.
I'm gonna go read the service manual and see what it says.

the pressure graph on page 12-00-45 shows a linear graph of high side pressure vs ambient temps. the hi side pressure hits 300 PSI at about 97 degrees ambient. thats the max border of a wide area of acceptable pressure, the low border of acceptable pressure is only 180 PSI at 97 degrees.




what do we get from all this,,,,eye strain.

normal operation is the pressure cycling switch. the containment switch is to keep things from blowing up.



I quit. :wave:

Perry

 

[pjtoledo]

will somebody please remind me to keep my fingers off the damn keyboard. this readin' 'n thinkin' is too much stress for me.

 

[3d914]

will somebody please remind me to keep my fingers off the damn keyboard. this readin' 'n thinkin' is too much stress for me.

pj, don't feel bad - I do the very same thing.