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Discussion Starter #1
My air conditioning has quit on my 97 escort wag. From what I can tell on this site, the ccrm could be the problem. I found a used one on ebay for $25 that matches the part number (F6SF-12B577-AA with a large letter R). I also went to Autozone's web site and typed in the word "RELAY" for my year and model of car. Guess what? I get a list of relays to choose from. A fuel pump relay, an A/c Compressor Control, and a radiator cooling fan motor. When I click on each of these I get a part number of MR76 and a price of $7.99. I get the same item number for all three items. Since these are all the same part number and price, does anyone know if this is all one part, i.e. the ccrm, listed three different ways? Could this be a very inexpensive replacement part from Autozone for the ccrm?
 

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The CCRM is a collection of relays inside a black box. It's possible to open up the black box and replace the individual relays if you're handy with a soldering iron. There are other threads on this forum on how to do it and which relay to buy.

But, it may not be the CCRM.

1. If you have a feeler gauge, check the size of the air gap on the compressor clutch. It's the thin space between the clutch face (the disc that spins somewhat freely when the a/c is off) and the rest of the compressor. If the gap is too large (because the clutch face wears down with age), the magnetic coil in the clutch isn't strong enough to close the gap and engage the compressor. You can narrow the gap by replacing a washer under the center bolt that holds the clutch face in place with a thinner one.

2. If the static pressure (i.e., when the a/c is off) is less than 45 lbs, the compressor will never turn on, or may engage once for a few seconds and never engage again. Static pressure should be at least 85 lbs (again, the pressure when the system is off) when it's 75 degrees outside. Low static pressure is usually always due to a system leak somewhere, but please don't try to use R-134 with stop leak to solve the problem, you'll only gum up the system and make matters much worse.
 

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Discussion Starter #4
Since I'm an amateur at auto repair, I'm going to ask some questions that I need child like answers to. I'm pretty handy as long as I have help.

1. I now have a second CCRM in my hands and have put it on my car. The car starts fine with the extra used one, but the A/C does not. I do not know for sure the replacement one works. They may both work and something else may be wrong. My question is, how can a beginner like myself test this module to see if either one works?

2. What is a feeler gauge and what should the gap size be? If the gap is too large would I not want to put in a wider washer and not a thinner one to narrow the gap?

3. What is the static pressure and how do I test this?

Thanks for the child like answers
 

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1. Get yourself a voltmeter. Unplug the single wire you see going to the A/C compressor clutch. Don't force it, you may have to depress a tab to unlock the connector. Turn on the engine, turn on the A/C. Measure the voltage between the wire connector and a ground like the metal A/C compressor case. It should be 12V or so. If it's about 12V, then the relay works, and you have enough refrigerant, but the clutch gap is too large or the clutch doesn't work at all.

2. A feeler gauge is a collection of thin metal strips used to measure gap sizes, usually on spark plugs. The A/C clutch air gap should be between 0.018" and 0.080". If it's larger than 0.100" the clutch solenoid won't be able to close the gap when energized and engage the compressor. The washer is between the clutch plate and the clutch solenoid, so a thinner one will narrow the gap.

3. Static pressure is the pressure in the A/C system when it's off and the pressure on the high side has equalized to the pressure on the low side. Like I said above, it should be 85 lbs, tested with a gauge connected to the low side port.

This project is a little complicated for a first-timer, especially because you're dealing with an A/C system. You might want to bring it to a mechanic you trust.

Out of curiosity, how did you know to remove the small bolt holding the CCRM connector to the CCRM? It's not obvious, and most people end up trying to force it apart before they notice it's not simply stuck and has to be unscrewed.
 

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Discussion Starter #6
Thanks for this information. It is starting to make more since to me.

In reference to measuring the static pressure, Do I use the same gauge that is sold in the kits to recharge an A/C system? I don't have it here in front of me, but I did as the instructions in the kit said and measured it with the A/c on high, not when it is off. The measurement seemed to be in the normal range according to the gauge (it was a green area marked normal), but the # on the gauge was not anywhere near 85. Again it was while I had the A/C on high. So will the presure gauge reading go way up when turning off the A/C?

At first I did try to pull he connector off with my hands and relizede real fast that something was holding it. I looked for clips but didnt find any. Then I looked at the replacement and noticed the thread in the center for a bolt. Then I separated the wires and noticed where the bolt was. I was getting ready to let my 9 year old have a shot at it.
 

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Low pressure side should not read above 45 psi when adding freon with the a/c on. I don't know much about a/c so I can't help you with the static pressure. The best way to add freon is with a set of manifold gauges that gives you low and high pressure readings. High side should not exceed 300 psi.
 

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Yes, you can use the gauge in the kit. When the A/C is turned off, the pressure will be about 85 lbs. on the low side (the gauge will not attach to the high side).

When the A/C is turned on and the compressor is working, the pressure will cycle between 20 lbs and 50 lbs, if the system is properly charged.

There's a low pressure switch on top of the receiver canister on the firewall. If you follow the hose where you connect the gauge back to the firewall, that's where it's located.

This switch is wired between the CCRM A/C relay and the compressor. When the low-side pressure is 47 lbs or higher, the switch is on. When the pressure drops below 23 lbs, the switch turns off.

When the A/C is off, the static pressure in the entire system is about 85 lbs. When the A/C is on and the compressor is running, the low-side pressure drops and the high-side pressure rises. When the low side drops to 23 lbs, the compressor stops, and the low side pressure starts to equalize, rising until it reaches 47 lbs. At this point the compressor turns back on, and the cycle repeats.

If it's undercharged, and the pressure never reaches 47 lbs, the compressor will never turn back on.

If you've already bought a kit, did it come with a can of R-134 that also contains "stop leak" or "conditioner"? Did you add any of that stuff to the system yet? If you haven't, please don't!! The additives only serve to muck up the A/C system, and should be avoided at all cost. You can get 12 oz cans of plain R-134 at walmart for $8 each. If you have a small, very slow leak, you can afford to add a can once a season, or even once a month, without killing your wallet. Anything larger requires a professional to fix properly.
 
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