A/C Clutch Issue

[azhodge]

hey guys, the compressor on my 88 stopped spinning. I noted the clutch was not engaged. power from the plug is 11.8 volts, when I take power directly from the battery which is 12.5 volts the clutch engages and the compressor works fine. I switched relays up front to no effect. the resistance is approximately 4.0 ohms. once when I plugged it back into the regular ac power plug I saw the clutch jump for a second as if trying to engage. your thoughts would be appreciated. thanks

[zippy_gg]

Did you, or the PO, install a hi-lo switch?
If your gas pressure is too low it will disable the clutch. Just a thought...

[azhodge]

it does have a high/low switch. that was my first thought. I bypassed it, and took the power reading (11.8) from that wire. I find it interesting that a wire coming directly from the battery at 12.5 activates the clutch but that using the existing line wire at 11.8 it does not engage??

[azhodge]

side note... it has a kuehl system in it. when it runs it is impressive//

[T77911S]

use a test light instead of a MM,.

sounds like bad connection/hi resistance that is reducing the current available to pull in the clutch.
just because a MM will measure 12v at a wire does not mean there is enough current there.
if there are crimped connections check those, they suck. I usually crimp and solder mine.
see if it has a low pressure cut out switch,.

[WYDBODY1986]

I had the exact same problem with my AC. I tested everything and it all checked okay but when I connected battery power to the compressor it ran fine. My problem ended up being my temperature switch in the center console. The old one tested fine but would not engage the compressor.

Brian

[azhodge]

Wow, so I guess the question is.. is it possible to bypass the console temperature switch to verify that it is defective?

[azhodge]

So that is interesting, I used a test light as 77911s suggested and got nothing. rechecked it with the meter and it says 12 v. this is all with the hi low switch bypassed.

[Hugh R]

I have the Seiko or whatever compressor. My clutch didn't engage and I tapped it while running with a stick and it started spinning. Dirt maybe.

[kuehl]

Originally Posted by T77911S

if there are crimped connections check those, they suck.

He does not mean Kuehl crimp connections suck, just crimp connections in general

Good catch on the Test light vs. MM.

You might have a 'frayed' connection (not enough strands; not enough amps).

If you use a separate power supply (grounded to compressor body) and positive
to the clutch and it engages, > then try positive to the power wire to the pressure switch and if it engages,> check your "Y" connector
between the pressure switch and and the original AC power female spade connector.

Power to the AC comp clutch comes from a long wire fed from the thermostat. The thermostat contacts can pit, corrode over time.
Power to the thermostat comes from the evap fan speed switch.

If you have to review the thermostat, on a 86-89, you need a phillips head screw driver and an hour of time for DIY.
Remove 4 screws to the back side cover of the center console, slip the cover out on the driver's side by gas peddle.
Remove 2 more screws on each side of the inner cover. Pull up the RH side floor mats.
Very carefully grab the wire harnesses and push them into the center console on the front RH corner,
while pulling down the Rubics cube fascia (3 stacks of controls that slide into together with a dove joint in
the plastics), be careful not to break the thermostat's aluminum cap sensor tube.
Green white and solid green wires; female spades to T stat male spades.
The wire female spades are a pita to pull off with your fingers; needle nose pliers and a wiggle.
The colors of the wires will be dark or faded, pull back on the heat shrink to verify green with white stripe
vs. solid green.

[azhodge]

I received the new temperature control for the console from Pelican. In a world of terrible prices I was pleasantly surprised to see it was only thirty eight bucks. Lots of angry people out there because it will not fit in the console without some modifications. but it is what it is, and it is new, and only thirty eight bucks. the two terminals on the back of the new switch are not marked the same or located in the same positions as the old switch. My question is, does it matter which terminals I plug the grn/wht and the grn wires into ? and if so how do I tell which one is which. appreciate all the help getting to this point.

[kuehl]

Originally Posted by azhodge

does it matter which terminals I plug the grn/wht and the grn wires into ? and if so how do I tell which one is which. appreciate all the help getting to this point.

.

The thermostat switch is a 'series' circuit, you can put either green/white or solid green on either spade and it will function either way.