A/C Stopped Working

CobraStar_LS8

CobraStar_LS8

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Is there a Relay somewhere because theres no electric currents going to my a/c compressor...It's been working and all of a sudden it stopped...still have refrigrant and the pulley spins freely with all pulleys and the clutch I can turn it by hand...I was convinced to replace the control head unit by jumping the sensor next to the high side port but with another control head it still not letting the clutch kick on
 
Don't think so? (well, there's the VCRM)

Here, let me write out the trouble shooting flow chart from my 93 manual:

A/C Compressor Diagnosis - No Operation

E1

* Start engine.
* Press Max A/C button.
* Check battery voltage. If not 12.5v or more, refer to section 14-00
* Does the A/C clutch engage?

Yes = Circuit functions properly. Test complete.
No = Go to E2.

E2

* Check for A/C demand voltage at pin 9 of VCRM.
* Is there 10 volts or more?

Yes = Go to E7.
No = Go to E3.

E3

* Check for voltage at input of pressure switch.
* Is there 10 volts or more?

Yes = Check reference pressures. If pressure is greater than 50 PSI, REPLACE switch. If pressure is less than 50 PSI, CHECK sysyem for leaks. SERVICE as necessary. Go to E1.
No = Go to E4.

E4

* Check fuse.
* Is there 10 volts or more?

Yes = Go to E5.
No = REPLACE fuse / CHECK ignition switch and wiring. SERVICE as required. REFER to section 11-05.

E5

* Check for voltage at the EATC control assembly.
* Is there power at input pin 26?

Yes = Go to E6.
No = CHECK wiring between fuse and control. Go to E1.

E6

* Check for voltage at EATC control assembly.
* Is there power at pin 25?

Yes = SERVICE wiring for EATC control assembly and pressure switch as necessary. Go to E1.
No = REPLACE EATC control assembly.

E7

* Check for voltage at pin 14 to ground.
* Is there 10 volts or more?

Yes = Go to E8.
No = Go to E10.

E8

* Ground A/C clutch near compressor.
* Does the clutch engage?

Yes = SERVICE ground between clutch / VCRM wiring. Go to E1.
No = Go to E9.

E9

* Check air gap between hub and pulley.
* Is air gap within specifications?

Yes = REPLACE clutch field coil.
No = RESET air gap to specifications. Refer to section 12-03. Go to E5.

E10

* Check for ground on pin 11 of VCRM. There should not be a ground.
* Is VCRM grounded at pin 11?

Yes = REFER to powertrain control / emissions diagnosis manual.
No = Go to E11.

E11

* VCRM is not turning A/C clutch on.

Concern may be caused by A/C high pressure transducer (ACP) or high engine temperature (ECT) REFER to VCRM diagnostics.


 
Phew! Glad that's over! :D

BTW, although it never mentioned it in the trouble flow chart, in another part of my book, it says that the A/C clutch cycling pressure switch prevents the A/C clutch from engaging at ambient temps below 45F - 50F

Just something to bare in mind...
 
Do you happen to have a diagram of plugs for the vcrm and eatc to show what pin is what?the only way I can get the clutch to engage is to jump the switch on top of compressor-I replaced that switch with a new one.even with switch jumped and clutch turning i get no cold air.
 
if you HAVE r134 in it..and verified this with a guage.

your symptom points TO the low pressure switch.
they are cheap and easy to replace..and if you are careful you wont loose the 134 that is in the system.

when you first break it loose it may leak, at that point continue to take it out swiftly and it will stop leaking when the valve below it closes.
if you pause or hesistat when it starts to leak your just gonna let more of the stuff out.

you can change it at the autopart store.

start to finish 40 seconds.

it's gonna take you longer to go in the parts store and get your hand ON the part then it is going to take to install the part.
 
go buy the part and bring it to webster and I'll do it.
lol
 
9_8_L_S_C said:
the only way I can get the clutch to engage is to jump the switch on top of compressor.
Click to expand...

there isn't a switch on top of the compressor, there is only a plug.

if you are referring to the round canister on the firewall on the passenger side of the car, that is the DRYER...the switch on the dryer is the low pressure sensor.

If you have proper refridgerant charge and the system doesnt turn on..it is a failed low pressure switch.

If you dont have a proper charge and you jump the low pressure sensor as a temporary "fix" your gonna nuke the compressor...dont do that.

replace the low pressure switch before you worry about etac pinouts
 
Here'sthe switch I replaced

DSC01349.jpg
 
when i unplug the low presure side and jump the 2 wires the clutch kicks on-when i unplug the other endhigh side)near air box the cooling fan kicks on-
 
9_8_L_S_C said:
when i unplug the low presure side and jump the 2 wires the clutch kicks on-when i unplug the other endhigh side)near air box the cooling fan kicks on-
Click to expand...

that is good info, I "thought" the other one might be the high pressure switch...and it very well may be.

But it's good info to know that is "what" turns the cooling fan on when the ac turns on and now that you mention it, it kinda makes sense..


So just to backtrack.

your compressor doesnt turn on, unless you jumper the low pressure switch plug?

you replaced the low pressure switch and it still doesnt come on?

AND.. you've absolutely ruled out that you are not indeed low on refridgerant?
Might want to double check, or verify with a second guage? Maybe?
 
yes to all and I had the ac done at jiffy lube and he said he pulled 2 pounds out and put 2 in-im thinking either 2 much in the system or corroded pin on vcrm-which i verified worked in another 98 lsc-did the self check on the eatc also and nada there
 
id put money on the jiffy lube guy screwed it up. when you come out for your recall i could talk a guy into throwing his gauges on it for a few bux
 
I'm stuck at this step...Which wire do I use to ground the clutch?

E8

* Ground A/C clutch near compressor.
* Does the clutch engage?

Yes = SERVICE ground between clutch / VCRM wiring. Go to E1.
No = Go to E9.
 
I don't get it either. I've looked at my car and looked at the book and I'm scratching my head. :confused:

You see, on the circuit diagram, it shows a puple wire, (power to A/C clutch) A gray / white wire (clutch return) and a black wire (clutch ground)

Yet, when I looked at the connector on my A/C clutch, I see a yellow wire and a brown wire and that's it. :confused:

Basically, what you need to do is find which wire is a ground and run a wire from that to a chassis ground - this will show you if the A/C field coil (the thing that moves the clutch) is working. (cos it takes the long wire to the VCRM and the VCRM itself out of the equation)

The connector for the coil is an absolute PITA to access!!! It's behind the pulley, on the side away from the engine. (don't get mixed up with the crank sensor on opposite side)
 
im not sure how a car a/c system works however i have run into this problem on heavy equipment. the thermostat in the evaporator coil controls the grounding of the compressor clutch and if that goes bad the clutch will never engage. i would find the ground wire out of the clutch and ground it to chasis at every connection making sure the compressor clutches in at every interval. this will ensure your g wire is good. or just get a schematic and follow the ground wire back to source and ground it there to see if you have a good ground. if it does have a thermostat i will almost bet that will be your problem.
 
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