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2000 Yukon XL with front AC issue

firebird_joe on Sun August 31, 2008 6:14 PM User is offline

Year: 2000
Make: GMC
Model: Yukon XL
Engine Size: 5.3L
Refrigerant Type: 134a
Ambient Temp: 88F40RH
Pressure Low: 32psi
Pressure High: 165psi
Country of Origin: United States

Hello gang,
It's been a while since I've been learking around here but it's good to see the forum is alive and active.

I have a little problem with my 2000 Yukon XL I need your help with
I have 70°F at the front center vent while the 2nd & 3rd rows are down around 50°F
At first I thought I might have a clogged O tube for the front half but with the pressure being so close to what the service manual calls for I'm thinking I may have something more electrical related especiialy since this one is equipped with an EEC module.

1. Will a scantool along the lines of Autotap (with GM license) grab DTC's and sensor inputs from the EEC?
2. Will I set a MIL light if the EEC throws DTC's?

Any ideas on where to start? I won't get my hands on the Autotap until later tomorrow so I have spent today reading up on the service manual and specualting on what could be wrong. Before I go start pulling the dash apart to measure the temp potentiometer and duct temp sensor outputs any ideas on what typcially goes wrong?

Any help is appreciated


I just went out and tried something a little different; I only turned on the the front AC not BOTH front and rear as before.
Now I get the following data:

85°F outside air
80°F at front vent (down 10°F)
lowside 23-44psi (cycling)
hi-side 125-105psi (cycling)
10 seconds off 5 seconds on

I think I need to go look for a leak...


Edited: Sun August 31, 2008 at 6:44 PM by firebird_joe

Chick on Sun August 31, 2008 10:20 PM User is offlineView users profile

Recover/recharge with the factory amount into a good vacuum, add some UV dye and yes, start looking for the leak.. While you have the system empty, I'd check the O tube anyway, running it low you may find something, or not..but I'd check it..Hope this helps..

Email: Chick


Freedoms just another word for nothing left to lose

Cussboy on Mon September 01, 2008 8:30 AM User is offline

Looking for a leak is a good idea; it sounds like you're a little low on refrigerant? When's the last time you added R134a? Ever?

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