Getting AC working.

[JustinSane]

Hi i cant get the aircondition to cycle on, i checked the pressure switch beside the low side fill valve and its got continuity across it and 12 volts comming in one side, the temps out side today are around 59 60 degrees but on my other cars that dont stop the AC from working, i noticed the lowest you can set the AC in the SHO is 60 so is there a chance it isnt comming on due to temps being to cold ? or should it at least kick the fans up and cycle some any way? if the coool temps out side arent the problem can some one tell me the steps in diagnosing where the problem is? such as where to check for voltages and what not.

 

[Ishodu]

Should be 12v to ground coming out both sides when the system is on. Just remove the plug and jumper the two together and see if it comes on. If so your low on charge (sounds like it). Don't let it run more then a second or two jumper.

 

[JustinSane]

yep i already did that , shoulda mentioned i jumpered it and it didnt come on, what i meant was 12 volts at the plug on 1 wire when unpluged , 12 volt both wires when plugged in. what about the high pressure side and compressor , where should i have voltages at and any relays or fuses to check? my car is missing the ownders manual so i dont knw what fuse does what.

 

[projectSHO89]

Attached find the layout of the fuse boxes and the schematic for the EATC etc. Missing from the EATC schematic is the inclusion of the WOT signal..

To understand A/C clutch engagement, refer to my post in the thread stickied above - "effects of having wrong CCRM"

FWIW, I've seen bad clutch connectors that cause no/intermittent electrical connection. Keep a lookout for them.

 

[JustinSane]

Thanks i will check this out this weekend, basicaly if i have 12 volt at the clutch wire then i know its the clutch right? i dont think the CCRM has been tampered with but perhaps it how do i know which onei have and which one should be in the car? its a 95 ATX by the way.

 

[projectSHO89]

Thanks i will check this out this weekend, basicaly if i have 12 volt at the clutch wire then i know its the clutch right? i dont think the CCRM has been tampered with but perhaps it how do i know which onei have and which one should be in the car? its a 95 ATX by the way.

It might be the clutch coil, the connector, or an open harness between the CCRM and the clutch coil connector IF you have 12V on the CCRM connector pin for the A/C coil. It's pretty easy to make a couple of resistance checks now to check continuity of the circuit and the electrical integrity of the coil that you have the circuit details in front of you.

See the aformentioned post regarding the correct CCRM. Your question is already answered.

Steve

 

[JustinSane]

I will check the voltages this weekend , where is the CCRM located on the car?

 

[projectSHO89]

I will check the voltages this weekend , where is the CCRM located on the car?

uh oh..... Under the radiator sight shroud. You did consult the above referenced thread, I hope. If not, you have little hope of diagnosing this except by guesswork.

What are the voltage readings at CCRM pins 21, 22, and 23 when the AC is supposed to be energized?

With the vehicle power off, what is the resistance reading from CCRM pin 23 to ground?

Steve

 

[JustinSane]

ok from what i gathered pin 23 22 and 21 are the lower row of wires with 24 being the closest to the bumper and 23 ect moving inward toward the firewall, i probed the wires with the harness still plugged into the CCRM which is a J by the way, and with the AC set to max AC the voltages was 0 at pin 23 a tenth of a volt at 22 and 21, the ohms between pin 23 while the connector was plugged into the CCRM and my batterys ground where 0 with the car off ,however the 2k setting said .062, which setting should i be using by the way? my dial says 200,2k,20k,200k, and 20m . any way all the other settings said 0 maybe 2k was picking up some minor resistance between the probes and the surfaces them selves.

 

[projectSHO89]

For these tests, the 200 or 2K range setting is fine.

Your readings indicate that the clutch coil is not open (good), but the signal from the cycling switch is not reaching the CCRM (or the PCM based on your other thread).

With vehicle power OFF, check for continuity between CRRM pin 21 and the RED/YELLOW wire at the cycling switch. Yours, I expect, will read open. In a normally functiong system it would show continuity.

If so, check the refrigerant containment switch. This switch is located immediately below the oil filter, mounted on one of the hard lines coming off the compressor. For testing purposes only, disconnect the connector at the switch and jumper the two pins with the PINK/LIGHT BLUE and the RED/YELLOW wires. Retest the system and see if the compressor clutch now engages. If so, the switch is bad. If not, there is an open circuit in one of the two circuits, either going to or coming from the containment switch.

The refrigerent containment switch is a dual-function switch. One set of contacts are normally closed while the other set is normally open. As long as the system pressure stay below 250 psi, the normally closed section passes the clutch demand signal from the cycling switch to the CCRM and PCM while the normally open section does nothing. If the pressure sensed by the switch exceeds 250 psi, the normally closed contacts open, removing the clutch demand signal and the normally open contacts close, grounding the High Speed fan signal to the CCRM and forcing the electric cooling fans to HIGH speed.

The electrical schematic is attached in the above post.

Steve

 

[JustinSane]

Is the cycling switch and the containment switch the same thing? i only ask as you indicated both have red/yellow wires? if they are not the same where is the cycling switch located?

 

[projectSHO89]

Is the cycling switch and the containment switch the same thing? i only ask as you indicated both have red/yellow wires? if they are not the same where is the cycling switch located?

The cycling switch is the one mounted on the accumulator can. The RD/Y wire runs from it to the containment switch.

Steve

 

[JustinSane]

ok the pin 21 and red and yellow wire have a reading of just about 0 so they are not open. i cant get to the other switch untill i have the car on a lift later. but based on that wire not reading open does it gove you any more ideas ? its like the control box in the dash isnt even turning the stuff on even though it says max AC on the LCD. the cycling switch is the one behind the plastic shield on the firewall right? the one i normally call the low pressure switch and its beside the low pressure side fill valve?

 

[AREA 91]

jumpered the 2 wires at the containment switch and nothing happened, still nothing turned on . could it be the EATC? i ran the self test and it had 0 codes.

 

[projectSHO89]

Per post #3, you reported having 12 V at the cycling switch. That is the only output of the EATC that has any effect on the operation of the compressor clutch.

That signal goes through the cycling switch and the containment switch and is then fed to both the CCRM and the PCM. You've reported having it at the cucling switch but not at pin 21 of the CCRM. Given the schematic posted above and the instructions already posted, trace through the circuit and determine where the voltage has been lost. Once you isolate the points where you have it and then you don't, you have identified the open circuit.

If you indeed are not getting your 12V at pin 21, the CCRM can never turn the compressor clutch relay on. Verify your voltage readings through the circuit, including at pin 21. Perhaps your previous reading was erronious.

Steve

 

[AREA 91]

ok after cleaning the contacts we have it kicking in and running however the compressor kicks on and off alot, like it runs 3 seconds and off 3 seconds, is that normal or is it to much pressure in the system?

 

[JustinSane]

well after adding some freon the on and off cycles stopped and driving home from area 91s place the AC worked the whole way home, however we did notice that when you run the AC and then turn the car off there is a hissing sound from around the battery / compressor area for about 10 to 15 seconds and then it goes away, we are thinking some sort of leak but we cant find it. also a few times we had to wack the front of the compressor with a screw driver to get it to kick in, we think that will get better as it gets used since it sat awhile. i guess the next step is freon leak detector.

 

[projectSHO89]

The short cycling was due to an undercharge.

It is normal to hear that hissing noise from under the battery after stopping the engine. That is the sound of the refrigerent flowing through the orifice tube as the system equalizes pressures. However, you do have a leak since the system was undercharged.

Your compressor clutch needs to be deshimmed due to excessive gap. There is an article in the old FAQs at www.shotimes.com with instructions.

Steve

 

[JustinSane]

ok thanks i will check into that, i think it was just a old charge and never charged up and it sat for a long time the car was towed back from another state and was to be used as a parts car i sorta rescued it, it didnt take much freon to top it off, half a can or so. thanks for all the help.