Need some help with my A/C PLEASE

[east302]

They included a PDF of the write-up. Here it is...

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[mattillac]

Is it just me or are all the images dead? This would be REALLY useful if I could see them!

On my mobile I had to click on the "switch to full site" / blue button top of the page to see the images.

Otherwise the images load (slowly) using the link below (archived version of the full page).

https://web.archive.org/web/2013071...k-series-trucks-hvac-control-unit-t77522.html

 

[Bigred81]

I’m sorry about my novel of a post. I keep finding bread crumbs on this trail of issue.

So I was looking in to testing the resistor. Then I noticed something that looks like it was burned on the ribbon circuit. I replaced that robin cable with my old one. The air will now move from top to bottom. But still no compressor when fan is on.


The resistor on the electrical board on the hvac controls looks good. No burned or signs of melting or high temps.

One thing I just noticed. The recirculating button lights up AND THE AC BUTTON lights up when I have fan speed turned off. As soon as I turn the fan on the lights on the buttons turn off.
Ok. I removed the one green wire from the right side plug that is 3 down on the gray plug. Nothing. Then Reassembled

I then removed green wire from the blower wiring harness. Still nothing. Then reassembled.

The replacement harness is done correctly. I’ve tripple checked it.

I understand this hvac panel may be bad. It’s just weird that previous hvac panel did exact same thing. I replaced it with this one and it worked fine for 20-30 minutes
I also disconnected battery cables for 20 minutes to see if it would reset something in the system. Still nothing. I still have no control over the air blowing out of any vents other than floor vent. Regardless if ac button is pressed or if I have the heater on. This is the first time I’ve had this issue with it. I’ve always been able to control that aspect

I read through the link provided. Thanks for that matillac. According to that I’ve got the symptoms from #1. Where do I start trouble shooting that fix?

like I said the transistor looks just fine. I don’t have my volt meter to test it.

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[SUBURBAN5]

Did you install the pressure switch yet?

 

[SUBURBAN5]

The one on top of the compressor on the aluminum line

 

[SUBURBAN5]

2nd you said you do have control of the air flow or no control? I thought you said air only comes out the floor?

 

[Keith Kunze]

AK49BWL Thank you so much. I’ve ordered a new resistor to see if that helps with the fan. The high cut off switch is under 250-360psi so I have to get the system discharged. It’s basically just a schrader valve like on tires for air. After replacing them I’m hoping it helps. You mentioned something earlier about the blower only blowing on the floor. It’s funny you said that. Because it now only blows air on my feet. No matter where I put it. Won’t come out of the dash or the defroster. Earlier today it worked but not now. Could you explain what that is again? I read your messages a dozen times to try to decipher them. I’m really no good at electrical. I have a pace maker in my chest and I get scared about frying it. But I’ll risk it for cool air so my kid can go with me. And just to clear up my blower works fine. Just won’t work on high still. But the other setting all work.

Just trying to help here. But did you check the relay under the dash on top of the air box. That relay controls the high speed on the control panel, the resistor only controls the lower speeds. You can access this by removing glove box.

 

[Bigred81]

Ok. I removed the one green wire from the right side plug that is 3 down on the gray plus. Nothing. Then Reassembled

I thin removed green wire from the blower wiring harness. Still nothing. Then reassembled.

The replacement harness is done correctly. I’ve tripple checked it.

That's the way it is on mine, I would have to assume they didn't change that much in two years...

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Are the wires on that plug a light green and a dark green with a white strip?

Looks like it.

Turn your A/C switch on and jump that connector.

Just trying to help here. But did you check the relay under the dash on top of the air box. That relay controls the high speed on the control panel, the resistor only controls the lower speeds. You can access this by removing glove box.

i did check that relay. It’s all good.

It stopped blowing on the floor after I replaced the electrical ribbon ribbon With one not burned up. But it’s back to square one. No ac and only blows on the floor. I’ve ordered a new resister for the HVAC box. After I replace that I’ll take it in and get the Freon out and have them install it. I don’t know. Tired of this.

 

[SUBURBAN5]

Here's my thought. Panel does sound bad especially if it's used however 2 panels in a row has me hesitant. 2nd blowing out the floor could indicate a stuck actuator or actuator door.... 3rd recirc button should move an actuator/ door even when ac off I believe. I hear mine when the truck off and I'm infront of the glove box power on of coarse 4th the lights turning on and off could be the blower switch. (Black thing ac knob turns behind hvac controls) if I wiggle mine I can turn the lights on or off. Btw too lazy to replace it cause it works lol

 

[AK49BWL]

This just keeps getting weirder and weirder lol. The A/C and Recirc lighting up with the blower switch off would tend to indicate that the green wire is incorrectly located, but removing the green wire doesn't help either. However... That burnt up trace is the ignition input to the control board, which kind of gives me an idea of what's happening... The off position of the blower switch is providing power to the circuit, and the ignition line isn't... So it's working like the ignition line's providing power and the other line isn't... Indicates that transistor is working. Then you replaced the control board. Now nothing works again. So with that new pdf, I have a new idea. With your not-burned-trace controller, try shorting those two transistor leads in the "fix" image together, and try your controls again.