Not my Yukon!

[amc]

Good day to you all, I'm here in upstate NY staying with my daughter + four kids while her husband is deployed. I'm an appliance technician (taking some time off) so I have mechanical abilities just never got into working on vehicles.

The AC will not come on. The AC button lights up. All the fuses are ok. The compressor is not coming on. As far as I can deduct it's not getting any power to it. I pulled the connector off of the low pressure switch and ran a jumper across those two wires, did the same on the high pressure switch. I didn't know if say it was low of refrigerant, with the LPS jumpered that it would come on right away? I didn't leave it jumpered long mostly because I'm just not sure how it all works. Plus it's not my rig and I didn't want to be the cause of creating additional issues.

I look forward to any tips on how to properly diagnose this thing. It's beginning to get warm here in Upstate. Thanks very much!

Anthony

 

[TacHoe]

need to include vehicle info. Year, model, miles? etc

 

[619NJ]

Having the same issue here. 99 Yukon, 147k. Compressor won't kick on. Getting a little warm in the Garden State.


619 the Chef choppin' lips and deep-frying Mud Ducks in the Yellin' Yukon and I'm gone...

 

[amc]

Sorry about that. It's a 1999 with about 150000. I'm not sure of the model (it's not here right now). It's a four door. 2 WD. Not sure what engine. Let me know if that's enough info.

Thanks!

 

[Kenric]

Oh course it is very hard to say without more details but the most common problem would be low refrigerant.

You can buy a very cheap gauge for the low side at most decent auto parts stores.

If the low side pressure is too low the compressor will not come on.

If it comes on but then the low side drops too low the compressor will shut back off, which is the source of AC compressor short cycling.

As far as the AC not trying to run goes, it should not have anything to do with the high side sensor.

Another potential root cause could be a bad compressor clutch or blown clutch fuse. That is easy to check by measuring voltage to the clutch. IF the low side pressure is good, and of your AC controls are set up right, when you turn on the truck the AC clutch should energize. If it does and the compressor does not spin then the clutch is probably bad. If it does not power up then it could be the fuse. Again, consideing that the conditions are right for the compressor to come on in the first place (refrigerant ok, HVAC controls asking for it to come on, etc)

Good luck.

 

[amc]

The connector just behind the clutch (on top) is a black and a green wire. Should the voltage be 12vdc between the two wires when the ac is switched on? Is the low pressure sensor the one on the very back of the compressor? The one on top looks to be the high pressure sensor. Let me know if that is correct please. Thanks again!