A/C compressor replacement

[callmejim]

Need a part number for a A/C compressor for my 1989 C1500, 5.7 motor, serpentine belt with flat spade dual plug on the front and a single wire plug on the rear
. Any help?

 

[GoToGuy]

Have you looked at Rock Auto or Summit, Amazon?

 

[PlayingWithTBI]

Need a part number for a A/C compressor for my 1989 C1500, 5.7 motor, serpentine belt with flat spade dual plug on the front and a single wire plug on the rear

Any R4 compressor will work, some are better than others - NAPA or AC DELCO are better but more expensive. I prefer new over reman. The 1-wire pressure switch is NLA you'll need to wire in the proper 2-wire switch in series with the low pressure cycling switch so you don't blow up the system when restarting on a hot day.

https://www.oreillyauto.com/detail/c/murray-climate-control/murray-climate-control-2-terminal-pressure-switch/mry0/35961/v/a/3384/automotive-truck-1988-chevrolet-k1500-pickup-4wd?q=A%2FC+high+pressure+switch&pos=3

Here's what I did on my 88 along with a relay for the clutch so I could get full battery voltage to it

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Edit: Check the air gap on the compressor before installing it - s/b 0.020" - 0.030". I had a new NAPA out of the box with >0.080". It smoked the clutch in about a week!

 

[Donald Mitchell]

I wonder what the diode to ground does?

 

[Donald Mitchell]

GM part number is 88964865, AC Delco new 15-20186.
https://www.ebay.com/itm/384722079500?epid=2308589431&hash=item5993390f0c:g:CPkAAOSw9J9cpd2i

 

[PlayingWithTBI]

I wonder what the diode to ground does?

It eliminates surging and/or chatter when activating the coil or something like that. It's been a century since I was into electronics.

 

[1998_K1500_Sub]

I wonder what the diode to ground does?

When the clutch coil is de-energized, the diode shunts the current generated by the collapsing magnetic field of the coil's inductance. Without it, a reasonably large and undesirable voltage spike would be generated at the coil's terminals (yes, just like in an ignition coil).

When the clutch is energized, the diode is reverse biased and carries no current.

Diodes are often used across the terminals of the coil of a relay / soleniod, for this purpose.

You'll see diodes used in this way in automotive (and other) applications, if you watch for them.

Capacitors are sometimes used in a similar, but not identical, role, e.g., the "condenser" (aka capacitor) in the old "points" ignition system.

 

[1998_K1500_Sub]

Any R4 compressor will work
The 1-wire pressure switch is NLA

Isn't the high-pressure cut-out switch on the R4 simply held in with a snap ring? It would seem the old one could be removed-reinstalled... if I'm right.

But maybe a new switch is desirable regardless.

 

[PlayingWithTBI]

Isn't the high-pressure cut-out switch on the R4 simply held in with a snap ring? It would seem the old one could be removed-reinstalled... if I'm right.

Yes it is but, the old 1-wire switch is hooked up to only open the recirculation door when it sees high pressure. There is no high pressure shutoff on the older R12 A/C systems that don't have the "Max" button so, when you shut off the truck on a hot day and start it back up shortly after, the pressures spike way over 450 PSI and can blow something up (the weakest point) like blowing the HP switch right out of the compressor. Ask me how I know

 

[1998_K1500_Sub]

Yes it is but, the old 1-wire switch is hooked up to only open the recirculation door when it sees high pressure. There is no high pressure shutoff on the older R12 A/C systems that don't have the "Max" button so, when you shut off the truck on a hot day and start it back up shortly after, the pressures spike way over 450 PSI and can blow something up (the weakest point) like blowing the HP switch right out of the compressor. Ask me how I know

OK, so this is a "Let's eliminate a problem in the old design with a fix from a newer design". And it's particularly a problem now because R134 conversions have greater high-side pressures than did R12, so this "upgrade" is practically a requirement.

Did I get all this right?

Make sense.

I assume OP is running R134a. Outta be using a new(er) condenser then too. If not... "replace it now" would seem to be the better action.