A/C clutch not kicking on....need a little technical help to diagnose

bergs

bergs

New member
Title states the issue.

Pressure sensor was jumped and still no activation of the compressor.

I searched a few threads so far and some of them mention pulling the HVAC fuse. I see nothing in either fuse box labeled as such so which circuit is it tied into?

I have not yet tried to measure the voltage on the two pin connector that leads to the clutch but figured checking the fuse would offer the same answer.

I'm technically adept so feel free to speak in technical terms as far as what else I need to check.

Thank you
 
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Which fuse is this tied into? Anyone?

EDIT: not sure if it matters but, 2005 V8 Sport with 206,xxx miles. It's a clean truck still so I'm not looking at a corrosion issue....at least not at this time
 
Last edited:
I'd try swapping that relay with the 115v inverter one, could save you a lot of time if it ends up being that common issue. I had that relay fail on mine.
 
Relay is good

With the relay removed and the a/c on, I am not seeing the latching signal (12v) in the engine bay fuse box. I jumped the compressor at the fuse box and it kicked on.
I am wondering, with the relay removed from the vehicle, is that a condition that would cause the a/c light to blink? Mine is not and I am becoming concerned that, with the absence of the signal voltage, the control panel might be the source of the issue.

Open to thoughts...
 
bergs said:
Relay is good

With the relay removed and the a/c on, I am not seeing the latching signal (12v) in the engine bay fuse box. I jumped the compressor at the fuse box and it kicked on.
I am wondering, with the relay removed from the vehicle, is that a condition that would cause the a/c light to blink? Mine is not and I am becoming concerned that, with the absence of the signal voltage, the control panel might be the source of the issue.

Open to thoughts...
Click to expand...

So you aren't seeing the input side of the relay get 12v?

True, might be worth pulling the button panel and reseating the connector, should take about 10 minutes.

The AC light blinks when the system thinks it is on but the compressor isn't cycling, generally signalling a fault in the fuse/relay/compressor.
 
drewm said:
So you aren't seeing the input side of the relay get 12v?

True, might be worth pulling the button panel and reseating the connector, should take about 10 minutes.

The AC light blinks when the system thinks it is on but the compressor isn't cycling, generally signalling a fault in the fuse/relay/compressor.
Click to expand...

Correct, no 12v input, A/C light on (no blinking), relay removed.

Is there is anything else between the relay and the climate control? Thinking I'll pull the climate control panel, inspect the board and maybe trace some wires in the engine bay in the off chance there is a break somewhere.

Looked at prices of control panels just for fun.....wish I didn't

:Cry:
 
Pulled the climate controls, checked the boards, reinstalled and still the same issue.

What next?
 
bergs said:
Pulled the climate controls, checked the boards, reinstalled and still the same issue.

What next?
Click to expand...

Not sure what to tell you besides swapping one out with a buddy's to see if it's the control panel. Maybe pressing the AC button with some force will engage it, maybe the switch is on its way out?

Beyond that I'm not sure what to say, except test all your fuses.
 
drewm said:
Not sure what to tell you besides swapping one out with a buddy's to see if it's the control panel. Maybe pressing the AC button with some force will engage it, maybe the switch is on its way out?

Beyond that I'm not sure what to say, except test all your fuses.
Click to expand...

Thank you for taking the time to post up. Everything so far has checked out with the exception of the signal getting to the relay.

Now if I only had a buddy...

:heh:
 
Kenworth said:
I had same issue , ended up low on freon
Click to expand...

exactly! if your ac compressor isn't cycling means either you are low freon or the clutch is out on the compressor. but again i had a donkey(dodge) that would kick the clutch on and off cause it was low. take it to a shop and see if you can get a free estimate?
 
The clutch didn't kick in when I jumped the sensor (located near the passenger headlight) but did kick in when I jumped the relay location and got cold air. That part makes no sense to me in that if I were low on freon, jumping the sensor would (or should) engage the compressor, no?

...and sorry to the folks that are helping me if a couple of my posts seemed dickish. Typing from my phone is proving to be a pain in my ass. I am grateful for everyone's help.

:love:
 
Try the fog light relay

I only kind of skimmed the other messages, so sorry if this is off base, but I had the relay problem with my AC, and I discovered that the fog light relay is the same part, I was able to diagnose a bad relay by replacing the A/C clutch relay with my fog light relay, and the subsequently order a new relay from Rock Auto. My local dealer wanted $75 for it, which I didn't feel was a fair price.
 
nightshade000 said:
I only kind of skimmed the other messages, so sorry if this is off base, but I had the relay problem with my AC, and I discovered that the fog light relay is the same part, I was able to diagnose a bad relay by replacing the A/C clutch relay with my fog light relay, and the subsequently order a new relay from Rock Auto. My local dealer wanted $75 for it, which I didn't feel was a fair price.
Click to expand...

The short and skinny is, no signal voltage is getting to the relay.

Relay is good
Compressor is good
Refrigerant level is good
 
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