A/C clutch and parasitic draw?

DIESEL1986

MEMBER
2005 GMC YUKON
5.3L
V8
2WD
AUTOMATIC
250,000 MILES

I have a 1.0-amp parasitic draw on my vehicle. I literally pulled every fuse and relay from the under-hood fuse box and the one in the driver's side of dash. It did not lose the 1.0-amp draw. I am super confused. Well, I put it all back together and now I have no A/C clutch engagement. I check all A/C fuses and have 14.4 v. I swapped the A/C clutch relay with knows hood relay and also have power at the 30 pin and the 85 pin so it's calling for A/C. I just don't have voltage at the clutch connector itself.

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

So, if the A/C clutch relay sticks on which is common it will cause the draw you speak of it will take out the compressor clutch coil as well. I would remove the clutch control relay and see if the draw goes away, and if so, disconnect the wiring from the compressor and with the system on check to see if the coil is getting power (Relay reinstalled). If so, replace the compressor or the compressor clutch coil.

This guide may help as well:

https://www.2carpros.com/articles/car-battery-dead-overnight

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

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Saturday, September 2nd, 2023 AT 4:55 PM

DIESEL1986

MEMBER
4 POSTS

Okay, so I figured out some stuff. I had the dvom set wrong. I didn't have the positive lead in the amp socket. So, my readings were off. I put it right and now with key off and set to test amps, the draw is.085 amps, so 85 milliamperes. This is high but acceptable from what I've read. But when I pull the 10amp HVAC fuse it drops to.007 amps. Then when I plug it back in it jumps to 2 amps for 5-7 seconds (presumably the HVAC is trying to reset) then it goes back to.085 amp.
I've been having HVAC issues where the vents will get stuck on hot when you adjust the temp from cold to hot. So, we just leave it on cold. I figured it must be the HVAC module as I've changed both the defrost actuator and the blend door actuator.

So, that's where we stand.

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Saturday, September 2nd, 2023 AT 6:11 PM

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

.085 amps is acceptable, you might just have a bad battery, please use this guide to be sure:

https://www.2carpros.com/articles/car-battery-load-test

Please go over this guide and get back to us.

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Sunday, September 3rd, 2023 AT 10:39 AM

DIESEL1986

MEMBER
4 POSTS

I just replaced the battery this weekend. Hopefully this is the issue. I am still fighting the HVAC staying on hot and not adjusting back to cold. Any ideas on that?

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Sunday, September 3rd, 2023 AT 11:59 AM

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

I think the problem is solved, for the HVAC issue please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Cheers, Ken