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Chevy Express Cargo COMP will not engage on its own

intheb0x on Thu July 10, 2008 7:58 PM User is offline

Year: 2006
Make: Chevrolet /GMC
Model: Express/ SAVANNA
Engine Size: 4.6
Refrigerant Type: R134A
Country of Origin: United States

Hello All,

i have another wired issue here, this 2006 cargo van is my work van.
it was bought new and the AC worked perfect, then someone pulled the AC fuse on accident and it never worked normally again.
i ran a 12+v wire from the fuse box to the comp and then the comp works perfectly and blows ice ice cold air. but im getting tired of having to get out and either reconnect it or dissconnect the 12V source.

i figured maybe the battery needed to be disconnected but i tried this and it still doesnt come on normally. one thing i did notice is even after disconnecting the battery for about 10 mins my radio stations were still intact making me think that its still saving power somewhere and the ECU isnt resetting.
any thoughts?

thanks alot for the help!

Edited: Thu July 10, 2008 at 9:40 PM by intheb0x

GM Tech on Thu July 10, 2008 8:16 PM User is offline

The newer radios don't forget their stations---

You need to diagnose the system- find out what isw wrong- a good wiring diagram will help you find out what is wrong..

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

intheb0x on Thu July 10, 2008 9:39 PM User is offline

well like i said the fuse was removed and thats it, nothing else was done to the vehicle.
this has happened to another van we have, its like once the fuse is removed the ECU somehow needs to relearn to send the signal to turn on the comp.
thats why i have to bypass it to get it to work.
i wish there was a way to relearn or something.

Chick on Thu July 10, 2008 9:41 PM User is offlineView users profile

Have you had the systems scanned? maybe it set a code that needs to be reset by scanner..Just a thought...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

intheb0x on Thu July 10, 2008 9:56 PM User is offline

theres no engine light at all,never has been.
ive never had the system scanned and i bet i cant get them to scan it either becauses it money out of there pocket.
if theres a way to manually reset all codes by doing a key trick or something i would do it.
legally none of the auto parts stores around here can reset the engine codes either, they can just tell you if there are any.

GM Tech on Thu July 10, 2008 9:57 PM User is offline

Are you sure the fuse is back in the right spot and it is good?--also check high pressure switch and low pressure switch- they are inputs to the PCM to command the a/c on.--

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Chick on Thu July 10, 2008 10:11 PM User is offlineView users profile

Quote
Originally posted by: intheb0x
well like i said the fuse was removed and thats it, nothing else was done to the vehicle.

this has happened to another van we have, its like once the fuse is removed the ECU somehow needs to relearn to send the signal to turn on the comp.

thats why i have to bypass it to get it to work.

i wish there was a way to relearn or something.

Have to ask though, why are people pulling the AC fuse, accident or otherwise?? Sounds like someone may be tapping into wires they shouldn't be..

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

GM Tech on Fri July 11, 2008 9:16 AM User is offline

A/C codes DO NOT set SES lights!! So going by the assumption the light is not on is wrong-- you may still have a code. have it scanned with a good scanner if all is else checks out.

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

intheb0x on Fri July 11, 2008 1:27 PM User is offline

ppl pulled the fuse because there assholes and wanted to break the AC so i could work harder. Im pretty sure its the correct fuse and if i swap fuses and put another one in the spot it still doesnt kick.

How would i check the switches? Remember the system is working great when its bypassed.

Thanks for the help

mk378 on Fri July 11, 2008 2:17 PM User is offline

I think GM Tech is saying that an A/C malfunction (such as might result from a missing fuse) will be detected by the ECM. After the guy took the fuse out, the next time you pushed the A/C button the ECM tried to turn the compressor on. But it didn't engage because the fuse was out. The ECM detected that the pressure didn't rise like it should have, and concluded that something must be wrong with the compressor (not smart enough to determine EXACTLY what is wrong with the compressor though). This sets a code that doesn't turn on the CEL, but it can be read by the tech at a dealer.

The code also will "lock out" the compressor to prevent further damage until the truck is brought in for service. The ECM will not try to engage the compressor again until after code is read out and cleared with a scanner.

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