A/C Compressor Coil - Please - one more time

[Marccus]

Marccus
SHO Member
Join Date: Mar 2002
Location: California
Posts: 400




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Quote:
Originally Posted by projectSHO89
Never use an ohmeter in any circuit that is powered.

Measure from the A/C output pin of the IRCM/ connector to ground. This will test the coil, the connectors, and the wiring harness all in one step. Haven't looked up the value, but I'd expect anywhere from 10-40 ohms on a good circuit. If it measures open, check the connector on the coil itself, I've had to use zip ties to secure the connection.

Steve

I didn't know the A/C pin number so I kept checking continuity between the pin (looked like a spade to me) and the coil connector. As you look into the male connector for the IRCM (the one with the pins), the pin that had continuity was on the bottom row and 2nd from the left.

I then found the following:

Pin to top female inlet on the connector: Resistance = o.5 ohm
Pin to bottom inlet on the femal connector: no continuity


Pin to ground: no continuity.

OK Here comes the dumb question:

Why would you want to measure resistance from the pin to ground. Aren't you interested in measuring the resistance in the wiring that starts at the pin and ends at the coil connector?



But let me go back and state how this problem started:

The A/C compresor was working fine.

I had to put in a new starter. During the installation I had to remove the coil connector to obtain better access. I broke off the snap part of the connector when I tried to connect it and I couldn't get the connector to stay on without the snap part.

I ordered a new connector, cut off the old connector and spliced in the new one. I checked that I connected the correct wire to the correct female inlet wire of the female connector (bottom connector inlet to black wire, top connector inlet to black wire with yellow stripe).

I started the car, put on the A/C. The compressor didn't kick in and hasn't started since.

There was still about 13 - 14 volts at the connector.

Maybe it is just coincidental that the compressor stopped working when I finished installing the starter and the new female connector, but I keep going over it in my mind if I touched any other parts other than the ones I have mentioned.

Can't come up with anything.

Should I just buy a rebuilt compressor?

Is my wiring correct?

Any Ideas?

 

[projectSHO89]

It would be helpful if you identified your car by year and engine. While the circuits are the same across model years, the diagrams are different in their layout for referencing the connectors and certain wires within the harness have different colors.

There is no indication you have a bad compressor or clutch coil. Most likely, it's just an open in the wiring.

See the stickied post IRCM/CCRM in the Electronics sub-forum. See my post #19 for exact details HOW this circuit works. Other posts within that thread gives the IRCM/CCRM connector C1019 layout and pin function.

Q1. Do you measure 13-14 volts at BOTH pins of the clutch coil? If so, you have an open ground in the portion of the circuit between the coil connector to C1019 pin 16 and internally to ground via pin 15.

Step-by-step test

1. Disconnect C1019 from the IRCM/CCRM and look into the harness (not module) connector. Using your multimeter, measure resistance from pin 23 (bottom row, 2nd from left) to pin 16 (bottom row, 4th from right). You should read approx 3.5 ohms if the circuit is complete including a good coil. Note: The connector face on the module itself has the pin numbers molded into the connector shell. If good, skip to step 3.

2. If open, measure resistance from pin 16 to the black wire of the coil connector. If open, you've found your problem to be repaired. If good, measure from pin 23 to the black/yellow wire at the coil connector. based on your previous reports, this should be good.

3. If both are good, measure from harness connector pin 15 (bottom row, 3rd from right) to vehicle frame ground or battery negative terminal. If open, troubleshoot open ground from pin 15 to ground G101.

4. If ground path from pin 15 to chassis ground is good, measure for internal continuity between pins 15 and 16 of the IRCM/CCRM module. If open, replace or repair the module. If good, you've missed something somewhere, start over.

Steve

 

[Marccus]

Thanks. Mea culpa regarding not stating the year .

It is 1989.

I'll follow your instructions and post on the results.

 

[Marccus]

It would be helpful if you identified your car by year and engine. While the circuits are the same across model years, the diagrams are different in their layout for referencing the connectors and certain wires within the harness have different colors.

There is no indication you have a bad compressor or clutch coil. Most likely, it's just an open in the wiring.

See the stickied post IRCM/CCRM in the Electronics sub-forum. See my post #19 for exact details HOW this circuit works. Other posts within that thread gives the IRCM/CCRM connector C1019 layout and pin function.
Steve

1989 SHO MTX

I measured the following:

top inlet (black/ yellow wire)of connector to ground: 13.9v
bottom (black wire) inlet of connector to ground: 0.42v

top inlet of connector is the the location of the snap clip that holds the connector to the compressor socket.

Resistance:

pin #16 to black wire of connector (bottom inlet): 0.61 ohms
pin #23 to black/yellow wire: 0.51 ohms
pin #15 to vehicle ground: ( didn't record but it is good as I checked continuity)
pin #15 ot pin #16: open - no continuity

OK need new IRCM/CCRM. I just bought a new one in 2002. Darn!

The reason I gave the voltages on the connector is I replaced it and I want to make sure I didn 't reverse the connections. Is top inlet of

So is connection of the black/yellow wire (13.9 volts) to the top inlet of the correct correct?

I'm concerned that if I did reverse the connection would this "knock out" the IRCM/CCRM - in other words it is MY fault I need a new one.

The top of my module reads:

a large letter M
M9CLXH
E9DF-12B577-AB

 

[projectSHO89]

Your voltage measurements at the coil connector are NOT consistent with your resistance readings.

If the internal IRCM circuit path between pins 15 & 16 is indeed open and the coil is good, you should have read around 13-14 volts on BOTH coil connector pins. Measure your coil resistance, it should be around 3.5 ohms.

If you do indeed have an open circuit internally between pins 15 & 16 of the IRCM, just install an external jumper. Won't hurt a thing.

Steve

 

[Marccus]

OK. I'll run the measurements again. But does it matter if I reversed the wires on the connector?

Secondly, how / where do I hook up an external connector if required?

I don't have my wiring diagrams with me since I am on a work assignment in SF and I'm from Southern California.

Sooner or later I'll get the problem fixed - hopefully sooner rather than later.

Thanks, you've been very helpful. If I had 1/10 of your knowledge, expertise and accumen I'd be happy!

 

[Marccus]

I took the measurements again. I keep getting the same results.

But first I need an answer to this question. I installed a new coil connector:



If I swithced the black and black/yellow wires, will it matter on whether the compressor operates or not?



I thought I crimped the connector pigtail wires correctly to the b and b/y wires. The pigtain wires are the same color. You never know.




Coil Resistance:
black wire to black/yellow at the connector: open
pin 23 to pin 16: open

black/yellow wire to vehicle ground: 13.3 volts
black wire to vehicle ground: 0.35 volts

piin 16 to black wire: 0.7 ohms
pin 23 to black/yellow wire: 0.7 ohms
pin 15 to vehicle ground: 0.8 ohms
pin 15 to pin 16: open

So what do your advise? New IRCM/CCRM? Please don't tell me to take the measurements again!!!!

 

[SHOZ123]

Coils are usually non polarity sensitive. You should be able to connect ground or hot to either wire.

 

[projectSHO89]

Marccus,

It is imperative that you make measurements EXACTLY as prescribed. If you don't, you'll only frustrate yourself and still won't have a resolution.

Your voltage readings indicate that the field coil is open. Measure it with your meter, it should be around 3.5 ohms. THIS IS THE THIRD TIME I'VE SAID THIS and still there is no report of it having been done.

pin 15 to pin 16: open

This measurement was prescribed to be taken at the module connector itself, not on harness to module connector. Perhaps I didn't make that explicit You are to be checking the internal module ground path. If open, see post # 5 above.

The coil connector polarity probably is not relevant. Since you still have an open circuit, it certainly is at this point.

Steve

 

[Marccus]

Hmmm ... I guess I'm not understanding what you are directing me to perform.

I thought I was measuring and reporting the resistance across the coil by measuring the resistance across the black wire and the black/yellow wire with the connector attached and the harness unplugged. That's what I've been reporting.

" Coil Resistance:
black wire to black/yellow at the connector: open "

So do I have to unplug the connector, physically put the the ohm meter probes on the male pins of the coil male receptacle on the compressor and record the reisistance?

Or keep the connector plugged in, cut the connector so I have a pigtail connected to the compressor coil and measure across the wires. The latter would be easier to physically perform.

I had inquired about this before, but perhaps it is moot because depending on your reply, this is still not how one should measure the resistance of the coil.

And that's the $64,000 question - how do I physically measure the resistance across the coil?

Regarding "pins" , I've been trying to make a distinction when I measure a "pin" or not.

That's why I use the words "connector female inlet" because a female connector doesn't have pins; a male connector does.

So when I was instructed to measure from pin to pin or pin to ground, etc. , I look for a pin and physically put my probe on the pin (or the spade) not realizing that I was supposed to be measuring the inlet pin receptor on the IRCM/CCRM itself.

I'll correct that and measure it correctly.

If you or anyone else can instruct me on how to physically measure the coil resistance, I would appreciate it.

I have wiring diagrams, but not with me, since I'm on a work assigment elsewhere.

Thanks.

 

[projectSHO89]

So do I have to unplug the connector, physically put the the ohm meter probes on the male pins of the coil male receptacle on the compressor and record the reisistance?

Yes, exactly. You will likely find the coil to be open if I interpreted your previous posts correctly.

Sorry, I assumed you were familiar with the vernacular of electronics/electrical circuit checks.

Connector pins come come in male and female versions, not just male. The female "inlet" is also a "pin", it's just described as a "female pin".

Steve

 

[Marccus]

OK. Thanks. for clarifying some terms.

I'm sorry for being so dumb with respect to this stuff as I realize I've taken a lot of your and others' time. Hopefully I can clear this up soon and everyone can move onto more interesting things!! Many thanks for your patience.

I'm not familiar with the terminology for connectors although I should be. I worked a summer with a company that built custom test equipment for the IDF (Israeli Defense Forces) and I had to drive around all the time to different companies and pick up different types of connectors - some were very expensive - I was amazed at how much they could cost!

I'll get going on this.

BTW, you were right in my other post when I had the Code 49 problem. I needed a new DIS. I could only find an aftermarket AC Delco part and it took 12 days for it to be delivered!!

But this is off topic and I'll go back to that post since a had just a brief question.

Thanks.

 

[naval-avi8or]

OK. Thanks. for clarifying some terms.

I'm sorry for being so dumb with respect to this stuff as I realize I've taken a lot of your and others' time. Hopefully I can clear this up soon and everyone can move onto more interesting things!! Many thanks for your patience.

I'm not familiar with the terminology for connectors although I should be. I worked a summer with a company that built custom test equipment for the IDF (Israeli Defense Forces) and I had to drive around all the time to different companies and pick up different types of connectors - some were very expensive - I was amazed at how much they could cost!

I'll get going on this.

BTW, you were right in my other post when I had the Code 49 problem. I needed a new DIS. I could only find an aftermarket AC Delco part and it took 12 days for it to be delivered!!

But this is off topic and I'll go back to that post since a had just a brief question.

Thanks.

Where in CA are you located.

 

[Marccus]

Right now I am working in Martinez and living in San Ramon, about 40 miles (?) northeast of Oakland.

Too far outside SF to go in often and have fun. It is BORING as all heck out here. Walnut Creek is about 20 miles away - but it is just too snotty for me.

I am on a temporary work assignment - year, right, 8 months so far.

I live "permanently" in Irvine, Orange County (or the Orange Curtain as I like to refer to it).


I try to get down to the LA area often.