No A/C compressor ground relay signal - S-10 Forum
 
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post #1 of 13 Old 04-05-2019, 07:13 PM Thread Starter
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No A/C compressor ground relay signal

Current performance harness & I'm not getting a ground signal to energize the A/C compressor clutch relay. The electric fan comes on with the AC switch. I can jump the relay & the compressor runs fine.
I have the low pressure switch jumpered & have verified the ground.
I'm thinking the computer is not sending the ground signal. Idea's?


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post #2 of 13 Old 04-05-2019, 11:37 PM Thread Starter
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Re: No A/C compressor ground relay signal

I have verified the power to the computer from the AC switch & the ground signal from the low pressure switch.
So I've either got a computer issue or a programming issue. I have an HP Tuner

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post #3 of 13 Old 04-06-2019, 08:55 PM Thread Starter
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Re: No A/C compressor ground relay signal

I checked and changed the programming to no avail. So I took the power input from the AC control & the ground signal from the low pressure switch to activate a relay & sent the ground signal through the original wiring to the stock relay.
I have AC!

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post #4 of 13 Old 04-10-2019, 11:25 AM
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Re: No A/C compressor ground relay signal

Are you using a red/blue or blue/green PCM. The 059 Blue/Green's won't work on a low pressure switch and won't send an a/c request signal. A variable high pressure transducer is required on the high pressure side for the computer to control fans correctly. The a/c request gets wired through the low pressure before the PCM just as a failsafe.

The Red/Blue 0411's work fine and you'd just need to check all the pins in terms of ensuring request, and signals are coming in and out on the correct pins.
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post #5 of 13 Old 04-10-2019, 03:01 PM Thread Starter
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Re: No A/C compressor ground relay signal

Thanks, it has a red and blue connectors. I have verified the blue 12v input from the body module & the green ground signal from the low pressure sensor.
I'm getting a P0480 & a P0530 code.
My bypass with an additional relay did make the AC function, but now I have a relay ticking like a clock when it calling for the fan because of temperature, not because of the AC load. It does it now even with my extra relay unplugged. I may have f'd up.
I'm assuming the 480 code for the fan is the primary culprit & but don't understand the secondary code "refrigerant pressure sensor A circuit"
I don't know if that is a tuning selection or?

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post #6 of 13 Old 04-10-2019, 03:33 PM Thread Starter
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Re: No A/C compressor ground relay signal

This is what I have programmed currently
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post #7 of 13 Old 04-13-2019, 07:49 PM Thread Starter
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Re: No A/C compressor ground relay signal

Ok, replaced the PCM with the same year, same part number but this one has a slightly different operating system & would not accept my tune file. I had to change all the parameters manually. Now the AC works as it's supposed to & no more solenoid clicking, BUT the fan that comes on with the AC, now runs anytime the engine is running!
It has to be a programming issue, but I haven't found it so far. Anyone have an idea what I did wrong?

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post #8 of 13 Old 04-18-2019, 08:57 AM
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Re: No A/C compressor ground relay signal

What tune and operating system are you running???

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post #9 of 13 Old 04-18-2019, 11:07 PM Thread Starter
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Re: No A/C compressor ground relay signal

To be honest I'm not sure how to answer that. I tuned it with HP tuners both computera say the were PO1, both # 09354896 & this one says CYCB the original I don't know.

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post #10 of 13 Old 04-23-2019, 02:20 PM
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Re: No A/C compressor ground relay signal

You have the wrong PCM, that's your issue.

You have a #09354896, while it is a P01 512kb LS1B PCM, it is specific to the vette, camaro, and Silverado. The vehicles it was used in utilized a high-pressure 5v transducer on the high side for hi/low speed fan control where electric fans were used and engine crank fan clutch control. The PCM you have is not a true 0411, it actually isn't an 0411 at all.

You need a #12200411, colloquially "an 0411" this has the proper support for analogue cycling with low pressure switch & AC request signal, and its OS will not look for a high pressure signal, It also won't control the hi/low speed fans on high pressure tables like the #09354896 will.
The #0411 is common to the S10's from 00-04' (ergo why it directly supports S10 ac systems...). The 0411 happens to be cross compatible with both types of A/C setup and can be made to work with either. This, along with multi x crank support, is part of the "versatility" that makes the 0411 the typical choice for most swaps.
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post #11 of 13 Old 04-25-2019, 09:58 PM Thread Starter
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Re: No A/C compressor ground relay signal

Thank you,
I have one coming, the original computer came with the used CP harness I bought & was supposedly originally programed by them.
I knew something was up when I could not load my tune into the replacement.

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post #12 of 13 Old 04-27-2019, 10:03 PM Thread Starter
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Re: No A/C compressor ground relay signal

That was it, my original tune file loaded & the AC and fans work like they should.

Thanks!

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post #13 of 13 Old 04-30-2019, 09:01 PM Thread Starter
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Re: No A/C compressor ground relay signal

Spoke too soon. The 1st time I drove it & it got up to fan temp the ticking returned. The computer is switching the fan relay in & out like a clock ticking, just like the other one did....It's also not engaging the compressor...

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