Need some help with my A/C PLEASE

[east302]

Does jumping the connector at the accumulator cycling switch engage the compressor? Could be a bum switch, I’ve gone through a few.

If you have a scanner, it would show if the computer is getting an AC request signal.

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Ground locations G103, 105 and 200:

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[SUBURBAN5]

I would follow east302 diagrams and confirm power. If you have something shorted or disconnected you should be able to trace it down. Man I know it sucks and time consuming. Goodluck and grab your favorite beverage. If you run across something that your unsure of make sure you let us know. I dont mind comparing mine as a reference.. just dont ask me to pull my dash lol

 

[Bigred81]

Plug is correct. There is supposed to be a loner prong with no where to go.

I will have to wait until I can get my volt meter to check the volts. I tested the relay and they are good. I used my power probe and bypassed the

Plug is correct. There is supposed to be a loner prong with no where to go.

I would follow east302 diagrams and confirm power. If you have something shorted or disconnected you should be able to trace it down. Man I know it sucks and time consuming. Goodluck and grab your favorite beverage. If you run across something that your unsure of make sure you let us know. I dont mind comparing mine as a reference.. just dont ask me to pull my dash lol

ok. I’ll have to check with bolt meter when I get home. Here’s what I know

1. hvac controls replaced and worked momentarily but never on high speed for fan. But now no AC engagement.
2. My relay is good as are fuses. Clutch engages when I jump it.
High and low side sensors are not causing problem. I jumped both high and low side and still didn’t work.

So it may be the resistor on hvac box for fan but I don’t think that would affect the compressor.
So I think the issue is somewhere between hvac controls and the relay under hood. Is that kind of correct? I’ll have to ask my friend if he can read those schematics. That’s a different language.

 

[AK49BWL]

If you'll look closely at the switch where that extra pin comes out, you'll see it's jumped over to the ignition pin. Almost like they were going to put on two ignition lines to share the load instead of giving everyone the headache of melted connectors and wiring.

The three relays (or four if you have a four-speed system) is only applicable to the 88-94 trucks. 95+ the relays got replaced by that switch that can't handle the load, hence the burned out connector and wires.

There are THREE A/C pressure switches, did you jump all three? There's one at the dryer, two at the compressor. One on the lines, and one on the back of the compressor.

One more thing. The A/C switch does not go to the A/C compressor clutch, nor the relay. It goes through the high pressure cutout switch on the A/C lines at the compressor, then to the PCM - the PCM then checks the status of the OTHER two pressure switches and decides whether to activate the relay to turn on the compressor clutch.

 

[Bigred81]

If you'll look closely at the switch where that extra pin comes out, you'll see it's jumped over to the ignition pin. Almost like they were going to put on two ignition lines to share the load instead of giving everyone the headache of melted connectors and wiring.

The three relays (or four if you have a four-speed system) is only applicable to the 88-94 trucks. 95+ the relays got replaced by that switch that can't handle the load, hence the burned out connector and wires.

There are THREE A/C pressure switches, did you jump all three? There's one at the dryer, two at the compressor. One on the lines, and one on the back of the compressor.

One more thing. The A/C switch does not go to the A/C compressor clutch, nor the relay. It goes through the low pressure switch on the A/C lines at the compressor, then to the PCM - the PCM then checks the status of the OTHER two pressure switches and decides whether to activate the relay to turn on the compressor clutch.

I can only find the two switches. The one on the dryer and the one on the back of the compressor. You added on the power to the compressor is not the switch. What am I missing?i got the two colored in red.

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[AK49BWL]

Is this the one you checked (behind the "high" text), or the one under the back of the compressor itself?

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The switch visible there is the switch that the A/C switch passes through on its way to the PCM. The one ON the compressor is the high side switch.

 

[Bigred81]

Is this the one you checked (behind the "high" text), or the one under the back of the compressor itself?

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The switch visible there is the switch that the A/C switch passes through on its way to the PCM. The one ON the compressor is the high side switch.

Yes. There is only one switch back there and I jumped it along with the switch on the dryer. Is that correct? I don’t see a third one to jump.

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[AK49BWL]

That's odd... You don't have an unplugged connector laying around near the high line at the compressor? I see what looks like should be the port for the switch behind the red cap, but nothing plugged into it.

Well actually if the compressor kicked over by jumping those two then it doesn't matter, maybe they deleted that switch on some models...

In that case I'd look closely at the circuit board on the HVAC controller and see if the traces going to the A/C switch are still intact. I've seen one that the trace going to the switch actually burned off.

 

[kennythewelder]

If everything else is good, then yes, it could ether be a nad ground or a short. You may have pinched a wire when reinstalling the dash, or doing the lift. The compressor is grounded to the engine at the mounting bracket. In a nut shell, you have to big of a draw on the system to over heat the wires like that. Sometimes the easiest way to get around something like that, is to just run a new wire from end to end. You know what wire over heated, get a new wire and replace the one that melted. When I did the big 3 mod on my truck, ( and I added 2 more grounds) I was suprised at how much better things worked in my truck. Lol my windshield wipers speed up, just for 1 thing.

 

[Bigred81]

Is this the one you checked (behind the "high" text), or the one under the back of the compressor itself?

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The switch visible there is the switch that the A/C switch passes through on its way to the PCM. The one ON the compressor is the high side switch.

So you’re thinking I should have another switch on the manifold on top of my compressor?

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