Yet another A/C Q - new clutch still problems

[GTOSHO]

I had intermittent A/C operation a few months ago. Found the gap on the clutch to be questionable so went to remove a washer and found the clutch and pulley to be very worn down to rivets. So ordered up a new clutch/coil and replaced. Worked somewhat better after that, but would cut out at times and I assumed I needed some more 134a (94' MTX). Finally bought a kit with low side gauge and coolant, hooked it up and got a reading of 105 psi (80-85 degrees outside). The car was running but the clutch was not engaged. After searching this site again, sounds like this indicates that the 134a charge may be okay so I jumpered the low side switch and still no clutch engagement. The coil/clutch are basically new and worked initially so the coil couldn't have gone bad already, right?? What other circuit controls power to the coil? Another concern is the clutch gap, when I set it I found that is varied several thousandths (5 or so) when I went around the pulley. Is this normal? What would be a next step (besides taking it into Ford)? Thanks for any thoughts.
Tim '94 MTX 100K miles

 

[rangerj]

GTOSHO,

You should be able to apply battery voltage directly to the clutch coil and the clutch coil should become a strong electromagnet. If not, it is defective.

If the coil is OK, then try to jump the low pressure switch connection again with the key on, engine off and the A/C in the on possition. The coil should be enegized and again become a magnet. If not, it could be a defective wire, a connection, or a blown fuse.

I think you are on the right track. Your pressure reading would indicate that the system has a sufficient charge to activate the A/c clutch.

Do the self test on the climate control system and see if any codes come up.

There is an excellent post by a Utah SHO club (or was it Colorado)member that walks you through the A/C electrical tests. It is excellent (with pictures), and maybe if he sees this he will post it again. Try a search.

Sorry I can't be more helpful, I'm away from my reference sources and MY computer. rangerj

 

[rangerj]

GTOSHO,

See NOOK's reply above. He referes to the web address of the Utah SHO club post for the test proceedures I referred to. Thanks Nook. If I remember right Nook is the author of the posting.

Again NOOK, it is excellent. thumb rangerj

 

[GTOSHO]

Thanks rangerj for getting me to that link/writeup. It is excellent and I went through all the electrical checks as outlined in it. The results were that I had power to all connections except the clutch connector and pin 23 on the IRCM. This is said to be power TO the IRCM, but I had power at pin 21 which is supposed to be power to the clutch connector. Maybe this is different on my car '94 versus the '91 in the writeup (or writeup has them switched)? Pin 21 is pink with blue stripe, pin 23 is black with yellow or white stripe. Clutch connector has black wires, one with yellow or white stripes. Not sure, but I want to make sure the IRCM module is indeed bad before shelling out the $139 or so for a new one. What would be the best source to get one for lowest $$ if in fact I need one?? Maybe I should try to apply power to this wire and see if the coil energizes?

 

[rangerj]

GTOSHO,

See Bizzy's post with the wiring diagrams. Rather than applying battery voltage to the wire why not test the pin for voltage?

Unless you know for certain that an electronic component is designed for battery voltage, and not a lesser amount, I would be hesitant to apply battery voltage.

Check for battery voltage at the A/C compressor connection, then work backwards using the diagrams. If you had a short in the wires it would blow a fuse. So, look for an "open" by doing continuity tests and/or voltage tests.

The IRCM is a package of relays, including the A/C and fan, and is operated with vehicle power, ie battery voltage. So the tests you propose should be OK.

A continuity test between the right pins should tell you if the A/C relay is stuck open, or a voltage test applied to one pin should come out the other pin unless the relay is stuck open. Try both! rangerj

 

[GTOSHO]

I located a wiring diagram and found that pin 23 of the CCRM (not ICRM for my year wink )is in fact power to the A/C compressor clutch coil which loops back to the CCRM to ground at pin 16. My test light indicated no power through the wire at pin 23 nor at the coil connector. If this indicated that the relay inside the CCRM for this circuit is bad, its the only one as all other relays, fan/fuel pump etc. work fine. I'd like to apply battery voltage to the wire out of pin 23 to check operation of the coil/clutch. Could this damage the CCRM further? How about somehow fixing only this circuit without replacing the whole CCRM? Wire in a new relay? Be nice to know if the CCRM for '94 MTX is the same for all years ('89-'95) P/N on mine is F3DF-12B577-AA.

 

[rangerj]

GTOSHO,

"A rose by any other name"! CCRM/ICRM (CCRM is the latest acronym for the same module (re-engineered?)

Anyway, you should be able to find a relay that has the same parameters as the one in the CCRM. The question then is, what are those parameters.

SHOZ123, anybody else with electrical expertise?

It should be easy, power in, power out, and a ground. Check with a Ford parts service for a single relay for a Ford A/C system. That way you should have a relay with the right electrical parameters. It's worth a shot. A single relay should be about $10.

Let us know how it works out. rangerj