AC issue ( No ac light indicator) at the control panel

[A97obs]

I just Got around to wanting to use the ac after a year of owning this truck through the winter and it had ac 100% last fall worked the day I purchased it.

The only thing I did was swap out the heater control panel for a used one from a parts yard only to get one with good mounting clips ( was not clipping into dash) When I checked fuses everything looked kosher . When I press the ac (button) it does not light up. The system 134 charge is full in the vehicle I was gonna jump the high side pressure switch but I am trying to do process of elimination.. first . I know it takes freon to kick on the ac pump ,but it also requires power at or from the control panel?
Any chance I'm missing a fuse ? How many are there for the ac system on the 92-99 suburbans


No orange light at the ac button

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My real only conclusion is I got a bad heater control panel at the ac button .

I've ran 12v test light at the ac compressor plug ( No power) but all the fuses that I know of all have 12v working

 

[1998_K1500_Sub]

Year and model please.

I could guess: 1997 Suburban.

Do tell.

Schematics are in the service manuals, you can find a link to them here:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

The service manual will provide debugging steps you can follow.

 

[A97obs]

Year and model please.

I could guess: 1997 Suburban.

Do tell.

Schematics are in the service manuals, you can find a link to them here:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

1999 c1500 obs last year

 

[A97obs]

Do tell.

Yes I can dig into it with a schematic , although I thought by mention the unusual
( No power) Illumination Indicator when ac button is on just might instantly yield a red flag for a easier direction, I'm not sure how power flows but I know the basics need power at the ac compressor and the high side switches have been known to go bad , I remember watching my uncle jump them on plenty of 90s cars to find the problem actually being just that . But I thought it must be with the control panel that's the only thing that's changed in one year as a ( Used) second hand part

 

[1998_K1500_Sub]

Here are the wiring pages from the 1998 service manual. Notice the wiring for the LED.

Notice too that you could jumper around the LED switch, using a jumper under the hood (to the DK GRN/WHT wire), to engage / check the compressor clutch engagement and cycling switch operation.

 

[1998_K1500_Sub]

by mention the unusual
( No power) Illumination Indicator when ac button is on just might instantly yield a red flag for a easier direction

See the fuse in the wiring diagram; it needs to be operational.

If the LED doesn't work, there's possibly:

- an incomplete ground connection to the control panel at connection / connector "2"
- internal wiring / switching problem(s) in the control panel
- a bad connection / connector at "5" on the control panel
- etc.

Note that the control panel shown in the wiring diagram I attached doesn't show any connection to the "recirc signal"; I think it's in error. The "recirc signal" would be the same as that on connector / connection "7", which in the diagram powers the "water valve".

 

[A97obs]

Couldn't I just jump these wires on this plug end to bypass and engine the system

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[1998_K1500_Sub]

Couldn't I just jump these wires on this plug end to bypass and engine the system

Jumping the two connectors in that fitting (shorting them together) forces the system into recirc mode. That's the function of that high pressure switch. See attached.

It'll also turn on the aux cooling fan, if so equipped.

It'll also enable the heater core coolant bypass valve, if so equipped (the Suburbans and some others have these).

You should install caps on all the AC service valves. Clean them of crap first; I usually give them a blast with Brakleen (use the straw) to remove debris, then let the Brakleen evaporate and install the caps.

 

[A97obs]

Jumping the two connectors in that fitting (shorting them together) forces the system into recirc mode. That's the function of that high pressure switch. See attached.

It'll also turn on the aux cooling fan, if so equipped.

It'll also enable the heater core coolant bypass valve, if so equipped (the Suburbans and some others have these).

You should install caps on all the AC service valves. Clean them of crap first; I usually give them a blast with Brakleen (use the straw) to remove debris, then let the Brakleen evaporate and install the caps.

So I replaced the used heater control panel Today with a new Dorman that came in. I now have a good lit recirc light and ac on light ! I paper clip jumped the pressure switch and nothing happened ... still no compressor clutch coming on or any cool air. Shouldnt I have power at the compressor harness when the ac control panel light is on . I know the system needs a certain amount to kick on the compressor

 

[A97obs]

You should install caps on all the AC service valves. Clean them of crap first; I usually give them a blast with Brakleen (use the straw) to remove debris, then let the Brakleen evaporate and install the caps

I had caps and have caps I took them off only per the photo and inspection , I am well aware of caps and their use. I'm trying to determine why I don't have power or even if the system was low the clutch would still kick off and on