Write-Up: AC Compressor & Clutch Replacement

Jack the R wrote:

Nuh-uh, I'm sure you wished you lived closer so your Riv wouldn't have been rusted out by road salt

Well, That Too.

Do you want me to drive down with everything I can think of for troubleshooting and fixing your problem.?

Would need to be done before the leaves start falling.

Oh Shit, I just had to hire a kid in the neighborhood to start raking the leaves so I can do the last cut on the lawn for the season.

Oh Well. I could always ship everything.

That's quite a drive. I'm thinking this is going to get put off to spring if not longer.

Now that I've got my bad HVAC module replaced, and the temperature readout on the HVAC control cluster isn't blinking, I'm ready to look at the AC again. I turned the temp down to its lowest setting, on the main unit and the passenger door control, and the AC clutch did not engage.

I looked at the relay bypasses on Car Wizard's Amazon Affiliates page - Link

But that's $53 for a set that includes at least three I have no use for.

Does anyone know where I can get the one relay bypass that I need to make the AC clutch engage?

Jack the R wrote:

Now that I've got my bad HVAC module replaced, and the temperature readout on the HVAC control cluster isn't blinking, I'm ready to look at the AC again.  I turned the temp down to its lowest setting, on the main unit and the passenger door control, and the AC clutch did not engage.  

I looked at the relay bypasses on Car Wizard's Amazon Affiliates page - Link

But that's $53 for a set that includes at least three I have no use for.

Does anyone know where I can get the one relay bypass that I need to make the AC clutch engage?

Remind us what you have tried?

On my car, every 3 years or so, since it was about 11 years old, I've had to top off the refrigerant. The symptom is, the clutch won't engage. My understanding is that after a certain age the hoses just won't hold refrigerant well, and although the leakage isn't detectable they will seep. One can replace the hoses and not worry about problems for 10-12 years, or one can top off the system. My hoses are still original.

Using the pressures in the service manual (and buying a better-than-bargain level gauge, or renting a manifold set and vac pump from Autozone), you can check pressures yourself to see if that's the problem. When pressure is too low the cutoff switch will disable the system. That switch looks a little like the oil pressure sender/switch, but is mounted on the AC compressor.

I dumped a bunch of coolant in it, and the clutch didn't engage, but at the time I had the problem with the bad HVAC module that could have kept the AC from kicking in.

Before I buy the AC tools, I want to do as much as possible to rule out the climate control unit. Most likely it isn't the problem, but I want to see if I can get the clutch to engage with a fuse relay first.

Jack the R wrote:

I dumped a bunch of coolant in it, and the clutch didn't engage, but at the time I had the problem with the bad HVAC module that could have kept the AC from kicking in.

Before I buy the AC tools, I want to do as much as possible to rule out the climate control unit.  Most likely it isn't the problem, but I want to see if I can get the clutch to engage with a fuse relay first.  

The small gauge on the AC refill can isn't that expensive.  I got mine from walmart. Something like $25 incl tax. Get the one with numbers on the gauge not just the color code, as the pressure range for the "green" pressure level is not exactly the same as what GM says is the OK range in the manual.

The manifold and vacuum pump, around here, can be borrowed from AutoZone for a 100% refundable deposit. I imagine a handyman-quality vac pump and manifold set over amazon.com would be in the $100 range.

I've got the single gauge that only reads the low side pressure. I've read that the double gauge set is necessary.

Hi Jack, hi Albert,
I agree that low refrigerant will trip the low-pressure switch & prevent clutch engagement.
Jack, what exactly do you mean by the "bad HVAC module replaced". I hate to think of it, but I know that the programmer still has to beg the PCM for compressor-clutch control... Have you tried just good ol' hot-wiring the clutch to make sure it's good?
Best,
Mark

HVAC module is the Blower Control Module.

https://www.rockauto.com/en/catalog/buick,1997,riviera,3.8l+v6+supercharged,1022050,heat+&+air+conditioning,blower+motor+control+module+/+resistor,6557

Eldo wrote:

Hi Jack, hi Albert,
I agree that low refrigerant will trip the low-pressure switch & prevent clutch engagement.
Jack, what exactly do you mean by the "bad HVAC module replaced".  

The modules that move the vent doors. I had to replace a split gear.

Eldo wrote:

I hate to think of it, but I know that the programmer still has to beg the PCM for compressor-clutch control...  Have you tried just good ol' hot-wiring the clutch to make sure it's good?
Best,
Mark

I'm trying to find a relay bypass - Link

so I can force the clutch to engage without messing with the wiring.

I've only been able to find these things sold in a package with a few I don't need.

Ahhhh, so it WAS a bit vague...  I thought it was the programmer, Larry thought it was the blower motor module, and it was actually one of the door-actuator pack motors. 80>

ANYway, a bad or disconnected motor will cause the 100-second blink on the CC head but it shouldn't have any effect on the compressor clutch...  Jack, I was only talking about a quick, crude test.  Can you get the connector behind the radiator hose off & run a couple of jumper wires to power?

I think I'd have to put the car on ramps and remove the plastic shield under the bumper.