Fans always on & idle jumps every 5 seconds?

[HopefulSHO]

Fans always on & idle jumps every 5 seconds? - FIXED!

Just like the title says...looks like everything underhood is connected right; I haven't pulled the codes yet, but otherwise it runs okay. But you can feel the engine surge a little bit every 5 seconds at idle. Dosen't matter what the ETAC is set to. Wtf?

Codes coming later..

 

[qiksho]

I am by no means an expert but I would say it has something to do with eatc setting. Like the a/c tryin to turn on. My 89, and now my 91+ (damnit) had/have a problem with the a/c clutch gap. I fixed the 89 before I sold it, but now my 91 does kinda the same thing u describe. It will cycle repeatedly and make a chirp/hence pull down the idle, or give a slight hesitation. I know this is caused by low amount of refridgerant. I bought a $30 dollar walmart r134a conversion kit and some die hoping to find my leak...so far haven't found it. I guess I will have to replace the whole damn system :laugh_ti: so typical... :headbang:

 

[HopefulSHO]

I was thinking that for a bit too - but it will do it even with the ETAC in the Off/Vent/Floor settings . Although now when I turn it on, I think I can hear a soft "clunk" from behind the etac unit. Dunno if that's norma or if it was there before. Gonna pull the codes this morning.

If the ETAC itself is screwed up I'm gonna scream. It's a real nice looking hard-button unit, and one of the reasons I bought the damn car. Although it does pass the self-tests.

 

[HopefulSHO]

SHO 'nuff..here's the codes:

539 - A/C on during KOEO. Too bad the ETAC was set to OFF
176 - already knew about
332 - knew bout that one too.

KOER gave me 116 (cold engine), 332 (knew), and 225 (didn't get it the second time..perhaps because the engine was still cold. Ran the KOER quite a few times and this was the first I've seen it.).


So basically my car thinks the air conditioner should still be running.
Any ideas where I should go from here fellow gurus? All input is greatly appreciated.

 

[projectSHO89]

KM40 DIAGNOSTIC TROUBLE CODES (DTCS) 67, 79/539: CHECK A/C INPUT

DTC 79/539 indicates the ACCS input to the Powertrain Control Module (PCM) was high during KOEO/KOER Self-Test.

DTC 67 indicates that during KOEO Self-Test, voltage was high on NDS (Pin 30) or ACCS (Pin 10) circuit.

NOTE:
Before entering this test, verify A/C selector is off (and shift selector is in PARK for AXODE and E40D vehicles). If A/C was on, turn off and rerun Self-Test. If DTC 67 or 79/539 is present, continue with this test.

l Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

l Install breakout box, leave PCM disconnected.

l Key on, engine off.

l Measure voltage between Test Pin 10 at the breakout box and chassis ground.

l Is voltage greater than 1.0 volt?

Yes
VERIFY operation of A/C demand switch. If OK, SERVICE short to power in A/C circuit (A/C demand or Power-to-A/C clutch). REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».

No
For 7.3L diesel:
GO to «KM41».
For all others:
REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».

 

[HopefulSHO]

Rock On!! Thank you projectsho!

Anyone know where the A/C demand switch is?

 

[HopefulSHO]

So here's where I'm at with this problem. Any input is totally appreciated..

So I pulled the plug that goes to the PCM and tested for voltage at pin 10 with the ignition switch to on. Nothing. So I went ahead and bought another D4U1 to put in there. Slid it in, hooked it up, started it up..

...wheeeee the sound of fans comes back on again . Double checked that there's no voltage at that pin with the key on. So I disconnected the connector that goes to the CCRM and checked for voltage at the pink/lt blue wire (same one that goes to pin 10 on PCM) and it reads a half a volt. This wire apparantly also leads to the "Refrigerant containment switch" witch I assume will be the high-side pressure switch for the A/C system.

How the **** does my PCM think it should have the system on without voltage to pin 10? I'm still getting the 539 code. Argh!

Anyways, if I can think of anything else to add I'll slide it in later; I gotta run and take the kids to the arcade.

TIA,

Jeremy

 

[HopefulSHO]

Fixed!!

For any of you that may ever have this problem, let me recap:

While the engine was running, the fans would always be on, and it would bump the throttle (as if it was expecting the compressor to engage) every 5 seconds. I ran the KOEO and came up with code 539 - A/C on during self test. But it wasn't! The ETAC was set to OFF.

ProjectSHO's info said to check pin 10 with the key to ON. So I checked (many times); No voltage. So I replaced the PCM - Same thing. 539.
Bah! What now? So I chased that Pink/light blue wire (goes to pin 10) around and came to the CCRM. All connections looked good & only measured .5 volts. So there's current bleeding but where from? Off we go chasing that wire again....on to the high-pressure cut out switch.
So I removed the connector that goes to the switch and start the car...
What's this? NO fans?! Werd!! Connect it back to the sensor and wheeeeeee on goes the fans! Houston we found the problem!

$26 later and I have ICE COLD A/C again! I'm stoked! I was expecting to pay a mad amount of money to fix this. This was the easiest repair I've ever done on this car if you count out the hours thinking and tinkering just trying to find the problem. Seems the switch shorted internally and was throwing current where it didn't need to go. Luckily it didn't keep my compressor engaged this whole time.

But now it seems (with the a/c on) my comperssor is almost always engaged.
Perhaps I need to grab a set of gauges and see how much refrigerant I've got in there. Either way, that's some cold air! Word.

 

[Rob94]

R134a. Your compressor will be engaged most of the time.