Folks, I have a 1999 Lighting - mostly stock and do not dive in much here in the UK, I decided to turn the AC on a feew weeks ago during a rare heat wave here in the UK, now the thing just stays on regardless of the tempreture or switch controls on the dash... This is ok, but winter is coming...-> Any Ideas ???

 

had that happen on an '05 Suburban at work... relay stuck open made the AC fan run all the time even with the vehicle OFF... had to disconnect the battery the day before we took it to the Chebby dealer.

--Russ

 

Sounds like you have a short or your switch relay is shot. Until you can get it to a dealer for repair, here are a couple of things you can do too shut off the compressor:
(1). Disconnect the high pressure switch


OR

(2). Disconnect the compressor electrical switch. The following photo is from a how-to I wrote up so just ignore the wording on the left side of the photo but pay special attention to the wording on the right side of the photo if you decide to disconnect the electrical connector.


Hope this helps.

Todd

 

It's always "on" unless you move the control to "Panel". Then it's not compressing/running---just in case you didn't know .

Dan

 

also floor...

 

Well then what about "floor/panel?"

 

Amazingly good post, Todd.

 

Thanks Tim!

 

I'm sure you already know but yes floor/panel is A/C

 

mine blows A/C when it is on:
panel, A/C, MAX, Floor/panel.

 

Todd - Will try this on the weekend - Do you know which and where the relay is - I will need to get this shipped to the UK !! Great picks !!

Thanks

 

deadmic8 just to make sure I understand correctly; when I posted, my understanding was that your A/C compressor runs continuously even with the selector **** in the "Off" position. Since this is my line of thinking I will continue on that assumption. After I thought about this for a little while, I'm thinking it's either the clutch cycle switch or you have a wire that has gone to ground somewhere. Now keep in mind that I am by no means an A/C guru, I'm just trying to help you troubleshoot the problem with the limited knowledge that I have. So it could be an issue elsewhere in the system. But based off my experience it sounds like the cycle switch.

The clutch cycle switch is located on top of the accumulator behind this wire shroud. It's going to be a real PITA to access.


Here is the actual switch.


It's been my experience that the switch can be removed from the accumulator without compromising the A/C system. Just disconnect the connector, take a wrench and remove the switch from the top of the accumulator. Make sure you have a new one to replace it with before you remove it. I believe the switch is about $20.00 US.

Something I didn't mention in my previous post is if you disconnect the connector is should disengage the compressor as the clutch cycle switch is disabled at that point.

Another thing that I didn't think of in my last post is you can pull the fuse for the compressor....don't know why I didn't think of that last night.

If this doesn't address the issue then IMHO you need to get your truck to a dealer so they can check your wiring.

Now if my understanding is completely wrong and the A/C does shut off when the selector **** is in the "Off" position the disregard all the info in both of my posts. I hope this helps you get it figured out.

Todd

 

Todd Thanks,

your thoughts are real valuable - I will need to check all the points you mentioned, it appears to me, after switching on the AC for the first time some weeks ago, it just stays on. If by changing the settings on the panel ot off etc, makes no difference... so all the points you raised are valid. Will post a update followwing the checks..

Thanks

 

Please do post any updates. If the problem isn't the clutch cycle switch or a wire grounding out then I am very curious to know what caused the compressor to run even when the selctor **** was in the off postion.
And your welcome!

 

nice reply's Todd.....good info.